Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

Abinaya Thennarasan Latha; Balasubramanian Murugesan; Blessen Skariah Thomas

doi:10.3390/buildings13051114

Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

Thennarasan Latha, Abinaya;Murugesan, Balasubramanian;Thomas, Blessen Skariah 2023-04-22 00:00:00 buildings Article Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates 1 2 , 3 Abinaya Thennarasan Latha , Balasubramanian Murugesan * and Blessen Skariah Thomas School of Architecture and Interior Design, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India; abinayat@srmist.edu.in Department of Civil Engineering, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India Department of Civil Engineering, National Institute of Technology, Calicut 673601, Kerala, India; blessen@nitc.ac.in * Correspondence: balasubm1@srmist.edu.in Abstract: This research explores the potential of using municipal solid waste incinerator bottom ash (MSWIBA) as a partial replacement for ﬁne aggregate and ordinary Portland cement (OPC) as a stabilizer in the production of compressed stabilized earth blocks (CSEBs). The study investigates the effect of varying levels of cement content (ranging from 0% to 10%) and MSWIBA content (ranging from 0% to 25%) on the strength and durability of CSEBs. The strength characteristics of CSEBs were evaluated through tests such as wet and dry compressive strength, ﬂexural strength, water absorption, and stress–strain behavior, while durability was tested through wetting–drying cyclic tests. The results indicated that CSEB blocks made with 20% MSWIBA content and 10% cement were able to fulﬁll strength criteria. Additionally, using these blocks could result in cost savings of 8% during construction when compared to using ﬁred clay bricks (FCB). Furthermore, varying the cement content while maintaining a constant proportion of MSWIBA showed a signiﬁcant change in the stress–strain behavior and a cost analysis performed for CSEBs stabilized with the optimal quantity of MSWIBA-OPC combination showed that they can be a viable alternative to conventional earth Citation: Thennarasan Latha, A.; blocks, providing an eco-friendly, sustainable, and cost-effective solution for construction initiatives. Murugesan, B.; Thomas, B.S. Compressed Stabilized Earth Block Keywords: municipal solid waste incinerator bottom ash; sustainable cementitious material; Incorporating Municipal Solid Waste compressed stabilized earth blocks; microstructure Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates. Buildings 2023, 13, 1114. https:// doi.org/10.3390/buildings13051114 1. Introduction Academic Editor: Haoxin Li Soil has been one of the primary construction elements for thousands of years. More than a third of the world’s inhabitants are still living in soil dwellings. In the UK, around Received: 18 March 2023 half a million earth houses were constructed before the 1900s and are still standing [1,2]. Revised: 16 April 2023 Nearly two-thirds of all homes in India are still constructed using soil [3,4]. Generally, Accepted: 19 April 2023 in regions where the climate is hot and dry, and rain is scarce, earth has been utilized Published: 22 April 2023 extensively for building houses [5]. Earth structures are becoming more popular nowadays because of their various environmental advantages, including low energy intensity, reduced CO emissions, recycling capacity and the potential to serve as a buffer to manage humidity Copyright: © 2023 by the authors. inside the house. Concrete blocks and burned clay bricks have been observed to emit 200 kg Licensee MDPI, Basel, Switzerland. of CO per ton and 143 kg of CO per ton, respectively [6,7]. More importantly, cement 2 2 This article is an open access article manufacturing generates huge quantities of greenhouse gases, and an estimated quantity distributed under the terms and of 5% of annual production of carbon dioxide is because of cement production [8,9]. conditions of the Creative Commons The usage of earth as a construction material is becoming more prevalent nowadays. Attribution (CC BY) license (https:// Fired clay bricks are often used in masonry walls, but their high energy consumption and creativecommons.org/licenses/by/ carbon dioxide emissions make them unsuitable, in addition to the growing energy cost and 4.0/). Buildings 2023, 13, 1114. https://doi.org/10.3390/buildings13051114 https://www.mdpi.com/journal/buildings Buildings 2023, 13, 1114 2 of 17 other associated environmental issues. Stabilized unﬁred clay bricks may be a sustainable solution for these issues. There are several techniques for making earth bricks, with adobe and compressed earth bricks (CEB) being the most common. Of these, CEB has proven to be particularly advantageous due to its low cost, durability, and eco-friendliness [3]. In this study, conventional earth blocks (CSB) were also considered. Compression is used to create sustainable bricks with good mechanical properties. However, not all soils are suitable for making CEB, and many researchers have resorted to modifying the soil by adding stabilizers, binders, or both [3]. This is necessary because the soil must meet speciﬁc requirements for CEB manufacturing, which may not be available in many cases. Stabilized earth seems to stand out among the environmentally friendly building materials [10]. Over the last ﬁfty years, compressed stabilized earth blocks (CSEB) have been used for load- bearing masonry construction in various countries such as the USA, India, the UK, Brazil, Nigeria, etc. [11]. These blocks are made by pressing wet soil and an appropriate stabilizer into a high-density block with the aid of a manually operated press [12]. Environmentally friendly CSEBs possess high strength and durability with excellent thermal insulation capabilities [13]. When compared to CSEBs stabilized with lime, cement- stabilized CSEBs have better strength and durability [14]. At a cement content above 4%, CSEBs beneﬁt from increased strength and durability [15]. At 10% cement, the strength has been observed to be twice that of 4% cement, and the quantity of cement varies with the nature of soil. A cement content above 15% has been considered uneconomical [16]. The increased cement content improves the stability, which in turn enhances the wet strength to dry strength ratio [17,18]. In the sand–clay matrix, there is the possibility that the smaller clay particles ﬁll the voids of sand particles, resulting in an increase in density and decrease in void spaces as mentioned by Sekhar et al. (2018) [11]. Furthermore, in a study concerning the usage of crushed brick waste to produce CSEB presented by Kasinikota and Tripura (2021) [19], the CSH gel also ﬁlls up the void, making the structure impermeable and thereby increasing the rigidity of matrix [20,21]. The disposal of municipal solid waste (MSW) is a major environmental concern worldwide [22]. In 2012, around 1.3 billion tons of MSW were generated, which is estimated to become 2.2 billion tons by 2025 [23]. Incineration is often regarded as the most efﬁcient method for recycling MSW because of its great volume reduction capability and the ability to recover energy [24]. Most of this refuse is discarded in landﬁlls without any kind of retrieval or re-use, resulting in signiﬁcant economic and environmental issues. The quantity of ash that is produced from MSW following the incineration process accounts for approximately 25% of the total weight of MSW. Landﬁll space is limited in countries with a high population density [25]. Recent developments show that solid waste materials may be turned into a valuable resource in a circular economy to improve resource efﬁciency. As the MSWIBA contains Ca, Si and Al, it may be a suitable candidate as a raw material for cement production [26]. Improved energy efﬁciency, compressive strength and thermal comfort may be achieved by using MSWIBA as an alternative building material. The production process of Compressed Stabilized Earth Blocks (CSEBs) requires a signiﬁcant amount of ﬁne aggregates [27]. Using municipal solid waste incinerator bottom ash (MSWIBA) as a raw material in CSEB production could be a viable option for recycling MSWIBA and conserving clay, making it an environmentally friendly option for constructing earthen houses [11,28]. This study explores the potential of using MSWIBA as a partial replacement for ﬁne aggregates in CSEBs and inv estigates its effects on the mechanical and durability properties of these blocks. The various tests were conducted on samples containing varying percentages of cement and MSWIBA, and the results were compared to those of conventional earth blocks. This research aims to contribute to the development of sustainable building materials that promote environmental responsibility and waste reduction. The tests conducted follow ASTM standards and Indian Standards Institution norms, including wet and dry compressive strength, ﬂexural strength, water absorption, stress–strain behavior, and wetting and drying cycles [19]. The study provides Buildings 2023, 13, 1114 3 of 17 an in-depth account of the use of MSWIBA and cement in producing CSEBs as an eco- friendly construction material commonly used in earthen construction. 2. Materials and Methods 2.1. Soil Soil (containing a signiﬁcant amount of clay) collected from a depth between 2 to 5 m below ground level in Auroville, Pondicherry (India), was selected as the raw ma- terial. The collected soil sample was air dried, crushed to remove clods and then sieved through a 4.75 mm mesh screen. According to the conventional procedures enumerated by SP-36 (Part1) 1987 [29], the physical characteristics including liquid limit, plastic limit, shrinkage limit, particle size distribution, speciﬁc gravity and free swell were determined Table 1 [9,19,30,31]. According to the Indian Soil Classiﬁcation System, this soil can be clas- siﬁed as CH. For the manufacture of CEBs, AS HB 195 [32] and IS 1725 [33] recommended a sand proportion somewhere between 30% to 75% and 50% to 80%, which is more suitable for production of CEB. The sand mixture of 70% was selected to fabricate the CEB and an optimal soil–sand mixture 30:70 was determined according to [19]. Table 1. Characteristics of soil. Property Parameter Soil Liquid limit, LL 61.45% Atterberg limit Plastic limit, PL 35.67% Plasticity Index, PI 25.78% Sand 51.78% Slit 25.55% Grain size Distribution Clay 22.67% Optimum moisture content (OMC) 19.67% Proctor Test Maximum dry density (MDD) 1820 kg/m Shrinkage Limit 18.23% IS Soil Classiﬁcation CH 2.2. Cement Ordinary Portland Cement (OPC) Type I was used to produce CSEB. The chemical com- position is shown in Table 2 [31]. Evaluation of the physical characteristics demonstrated that the speciﬁc gravity was 3.15, initial and ultimate setting times were, respectively, 145 and 309 min, the 28-day compressive strength was 49.1 MPa and its ﬁneness was 326 m /kg Table 2. Table 2. Chemical composition of municipal solid waste incinerator bottom ash and OPC. Chemical Composition (%) Compound MSWIBA OPC (Type I) SiO 64.75 22.40 Al O 0.78 5.13 2 3 Fe O 0.38 3.98 2 3 CaO 14.85 61.64 MgO 0.74 1.26 K O - 0.61 Na O - 0.09 2 Buildings 2023, 13, 1114 4 of 17 Table 2. Cont. Chemical Composition (%) Compound MSWIBA OPC (Type I) SO - 1.14 C 15.53 - LOI - 3.75 2.3. Municipal Solid Waste Incinerator Bottom Ash (MSWIBA) The MSWIBA was collected from an incinerator plant located at Manali, North Chennai (India), where the MSWI bottom ash is produced at a rate of 2000 kg per day. The air- dried and pulverized MSWIBA, passing through a 4.75 mm sieve, was used to produce CSEBs [34]. The chemical composition of MSWIBA particles is shown in Table 2. The MSWIBA particles with a speciﬁc gravity of 2.30 were classiﬁed as Class F bottom ash. 2.4. Soil–Admixture Proportions This study examined the impact of various soil and admixture combinations on the strength and durability of compressed earth blocks. MSWIBA was used to replace ﬁne aggregates (sand) at a rate of 0% to 25%, depending on the mix. Based on the literature [26], blocks were prepared with varying cement contents (0%, 6%, 7%, 8%, 9%, and 10%). In evaluating the strength of the compressed stabilized earth blocks (CSEBs), a standard period of 28 days was adopted for all the casting blocks, irrespective of their mix ratios. This time period is widely accepted as it allows sufﬁcient time for the stabilizer material to cure and hydrate, thereby achieving the desired strength and durability of the CSEBs. By adopting this testing period, this study was able to obtain valuable information about the engineering properties of the CSEBs, including their strength and durability, which are critical factors for evaluating the quality of the blocks and identifying their potential uses. Table 3 contains detailed information regarding the type of test performed, as well as the quantity of blocks utilized in each test for each mix ratio. Table 3. Combination of cement and MSWIBA considered in this study. Cement MSWIBA No of Samples Testing 0% 5 Dry compression strength 6% 5 Wet compression strength 7% 0%, 5%, 10%, 15%, 5 Flexural strength 8% 20%, 25% 5 Water absorption 9% 3 Stress–strain behavior 10% 5 Wetting–drying test 2.5. Optimum Moisture Content (OMC) The CSEB preparation test was administered in a proctored environment, but with some adjustments. According to the deﬁnition, the optimum moisture content (OMC) is the point at which the dry density of the mixture may be maximized for a given level of compaction. When determining the OMC, the same methods used by [7,27,35,36] were applied. Both stabilized and un-stabilized soils were tested for no more than 45 min following the addition of water. A technique for measuring the hardness of a mixed dry mix is presented by [27]. CSEBs produced with 10% cement show the dry-density OMC. An OMC of 12–16% and a maximum dry density of 1812–2154 kg/m were observed for all the samples. The drop ball test, recommended by [27], was also carried out to assess the accuracy of water addition. Buildings 2023, 13, x FOR PEER REVIEW 5 of 17 sieved through a 1 mm mesh. In addition, the sand and MSWIBA were sieved through a 4.75 mm sieve. According to the calculations, the extent of air-dried materials, including soil, sand, MSWIBA and cement, were measured and combined [30]. According to the testing methodology, the soil was then mixed with the required Buildings 2023, 13, 1114 5 of 17 quantity of cement–MSWIBA. For the fabrication of CSEBs, 0–10% of cement and six pro- portions of MSWIBA (0%, 5%, 10%, 15%, 20% and 25%) were employed. Over-integrating MSWIBA by more than 25% would have led to block failure because of the soil’s low clay 2.6. Optimum Fabrication of Compressed Stabilized Earth Block concentration. The prepared wet mixture was scooped into the press mold, and any over- The dimensions of the blocks made using a block manufacturing machine were 240 mm age was afterwards removed. After the mixture was compacted using static compaction, 115 mm 90 mm in size. Figure 1 illustrates that the process of preparing blocks includes the block was gently removed from the compactor and placed on a level surface to cure multiple stages, such as batching, mixing, placing the mix, compacting, and ejection of the [37]. Blocks that had been pushed out of the mold were measured for weight and cured blocks. The lumps of dried soil were manually crushed with a rammer and then sieved for 28 days in a moistened tow sack. When the block was ejected, the weight and date of through a 1 mm mesh. In addition, the sand and MSWIBA were sieved through a 4.75 mm preparation were recorded, and an appropriate identiﬁcation number (for the series used) sieve. According to the calculations, the extent of air-dried materials, including soil, sand, was assigned for future reference. MSWIBA and cement, were measured and combined [30]. Figure 1. Figure 1. Flow Flowchart chart of produ of production ction of CSEB. of CSEB. According to the testing methodology, the soil was then mixed with the required quan- 2.7. Test Methods tity of cement–MSWIBA. For the fabrication of CSEBs, 0–10% of cement and six proportions The compressive strength of the stabilized earth blocks was measured using a 100- of MSWIBA (0%, 5%, 10%, 15%, 20% and 25%) were employed. Over-integrating MSWIBA ton compression testing equipment as per IS 3495 (Part 1): 1992 [38]. The combination of by more than 25% would have led to block failure because of the soil’s low clay concentra- wet and dry compressive strength was measured since wet strength may be advantageous tion. The prepared wet mixture was scooped into the press mold, and any overage was in the worst-case scenario. According to IS: 5454-1978 [39], a total of ﬁve samples were afterwards removed. After the mixture was compacted using static compaction, the block tested for each variation. The average value of the ﬁve samples was then used to represent was gently removed from the compactor and placed on a level surface to cure [37]. Blocks the compressive strength of all the mixtures tested. Figure 2a,b shows a test set up for that had been pushed out of the mold were measured for weight and cured for 28 days in a compressive strength and observed sample failure. The minimum acceptable compressive moistened tow sack. When the block was ejected, the weight and date of preparation were strength for the stabilized earth block is 3.5 MPa, according to IS: 1725-2013 [33]. The spec- recorded, and an appropriate identiﬁcation number (for the series used) was assigned for imen was prepared before subjecting it to the compression testing machine. The uneven- future reference. ness in the bed faces removed by grinding, resulting in two smooth and parallel surfaces. Cement mortar was used to ﬁll up the frog and any other holes in the bed. Then it was 2.7. Test Methods placed under moist jute bags for one day before being immersed in water for 3 days to The compressive strength of the stabilized earth blocks was measured using a 100-ton complete the process. To determine the wet compressive strength, the blocks were soaked compression testing equipment as per IS 3495 (Part 1): 1992 [38]. The combination of wet for 48 h in clean water, then were surface cleaned and tested using a universal testing and dry compressive strength was measured since wet strength may be advantageous machine [40]. in the worst-case scenario. According to IS: 5454-1978 [39], a total of ﬁve samples were The ﬂexural tensile strength in terms of modulus of rupture was determined by sub- tested for each variation. The average value of the ﬁve samples was then used to represent jecting specimens to a three-point bending ﬂexural test, as speciﬁed in Indonesian Stand- the compressive strength of all the mixtures tested. Figure 2a,b shows a test set up for compressive strength and observed sample failure. The minimum acceptable compressive strength for the stabilized earth block is 3.5 MPa, according to IS: 1725-2013 [33]. The specimen was prepared before subjecting it to the compression testing machine. The unevenness in the bed faces removed by grinding, resulting in two smooth and parallel surfaces. Cement mortar was used to ﬁll up the frog and any other holes in the bed. Then it was placed under moist jute bags for one day before being immersed in water for 3 days to complete the process. To determine the wet compressive strength, the blocks were soaked Buildings 2023, 13, x FOR PEER REVIEW 6 of 17 Buildings 2023, 13, 1114 6 of 17 ard SNI 03-6458-2000 [19], similar to the speciﬁcations in ASTM C67-02c [41]. The speci- men was loaded until failure, at a constant rate of 2.5 kN/min for 240 mm in a span using a universal testing equipment with a capacity of 200 kN. Figure 3a,b shows the arrange- for 48 h in clean water, then were surface cleaned and tested using a universal testing ment of the samples for ﬂexural strength test. machine [40]. Buildings 2023, 13, x FOR PEER REVIEW 6 of 17 ard SNI 03-6458-2000 [19], similar to the speciﬁcations in ASTM C67-02c [41]. The speci- men was loaded until failure, at a constant rate of 2.5 kN/min for 240 mm in a span using a universal testing equipment with a capacity of 200 kN. Figure 3a,b shows the arrange- ment of the samples for ﬂexural strength test. (a) (b) Figure 2. (a) Test set up for compressive strength and (b) observed crack patt ern of the sample. Figure 2. (a) Test set up for compressive strength and (b) observed crack pattern of the sample. The ﬂexural tensile strength in terms of modulus of rupture was determined by subjecting specimens to a three-point bending ﬂexural test, as speciﬁed in Indonesian Standard SNI 03-6458-2000 [19], similar to the speciﬁcations in ASTM C67-02c [41]. The specimen was loaded until failure, at a constant rate of 2.5 kN/min for 240 mm in a span (a) (b) using a universal testing equipment with a capacity of 200 kN. Figure 3a,b shows the Figure 2. (a) Test set up for compressive strength and (b) observed crack patt ern of the sample. arrangement of the samples for ﬂexural strength test. (a) (a) (b) Figure 3. (a) and (b) Flexural test setup for CSEB. The water absorption (WA) test according to IS 3495 (Part 1): 1992 [38] was performed on ﬁve samples (for each variation), as per IS: 5454 1978 [39]. con The initial weight was measured after the specimen was cooled to room temperature (M1). The specimen was then immersed in potable water for 24 h. The ﬁnal weight was taken after surface drying (b) Figure 3. (a) and (b) Flexural test setup for CSEB. Figure 3. (a,b) Flexural test setup for CSEB. The water absorption (WA) test according to IS 3495 (Part 1): 1992 [38] was performed on ﬁve samples (for each variation), as per IS: 5454 1978 [39]. con The initial weight was measured after the specimen was cooled to room temperature (M1). The specimen was then immersed in potable water for 24 h. The ﬁnal weight was taken after surface drying Buildings 2023, 13, 1114 7 of 17 Buildings 2023, 13, x FOR PEER REVIEW 7 of 17 The water absorption (WA) test according to IS 3495 (Part 1): 1992 [38] was performed Buildings 2023, 13, x FOR PEER REVIEW 7 of 17 on ﬁve samples (for each variation), as per IS: 5454 1978 [39]. con The initial weight was measured after the specimen was cooled to room temperature (M1). The specimen was for three minutes. Figure 4 shows the water immersion, surface drying of block and ﬁnal then immersed in potable water for 24 h. The ﬁnal weight was taken after surface drying for three minutes. Figure 4 shows the water immersion, surface drying of block and ﬁnal weight for the waste absorption test. The specimen was weighed 3 min after it was taken for three minutes. Figure 4 shows the water immersion, surface drying of block and ﬁnal weight for the waste absorption test. The specimen was weighed 3 min after it was taken out of water (M2), as shown in Figure 4. According to IS: 1725-2013 [33], the average water weight for the waste absorption test. The specimen was weighed 3 min after it was taken out of water (M2), as shown in Figure 4. According to IS: 1725-2013 [33], the average water absorption should not exceed 15% of the weight of the material. out of water (M2), as shown in Figure 4. According to IS: 1725-2013 [33], the average water absorption should not exceed 15% of the weight of the material. absorption should not exceed 15% of the weight of the material. Figure 4. Flowchart of water absorption test. Figure 4. Flowchart of water absorption test. Figure 4. Flowchart of water absorption test. The alternate wett ing and drying tests were carried out in accordance with IS: 1725- The alternate wetting and drying tests were carried out in accordance with IS: 1725- The alternate wett ing and drying tests were carried out in accordance with IS: 1725- 2013 [33], which is comparable to that mentioned in ASTM D559-03 [42]. Three specimens 2013 [33], which is comparable to that mentioned in ASTM D559-03 [42]. Three specimens 2013 [33], which is comparable to that mentioned in ASTM D559-03 [42]. Three specimens from each series were dried in a ventilated oven at 60 °C until their weight was constant. from each series were dried in a ventilated oven at 60 C until their weight was constant. from each series were dried in a ventilated oven at 60 °C until their weight was constant. The air-cooled blocks were immersed in water at room temperature for 5 h, and then dried The air-cooled blocks were immersed in water at room temperature for 5 h, and then dried The air-cooled blocks were immersed in water at room temperature for 5 h, and then dried in an oven at 70 °C for an additional 42 h. The dried blocks were scraped on all six sides in an oven at 70 C for an additional 42 h. The dried blocks were scraped on all six sides in an oven at 70 °C for an additional 42 h. The dried blocks were scraped on all six sides twice using a wire scratch brush, using a force of 1.5 kg for each stroke The method used twice using a wire scratch brush, using a force of 1.5 kg for each stroke The method used to twice using a wire scratch brush, using a force of 1.5 kg for each stroke The method used to scrape the dried blocks involved using a wire scratch brush to scrape with a force of 1.5 scrape the dried blocks involved using a wire scratch brush to scrape with a force of 1.5 kg to scrape the dried blocks involved using a wire scratch brush to scrape with a force of 1.5 kg for each stroke. To ensure the accuracy of the pressure applied by the brush stroke, we for each stroke. To ensure the accuracy of the pressure applied by the brush stroke, we kg for each stroke. To ensure the accuracy of the pressure applied by the brush stroke, we clamped the wider face of the specimen on one corner of a platform scale and set the scale clamped the wider face of the specimen on one corner of a platform scale and set the scale clamped the wider face of the specimen on one corner of a platform scale and set the scale to zero and then placed a standard weight of 1.5 kg on the brush to measure the pressure to zero and then placed a standard weight of 1.5 kg on the brush to measure the pressure as to zero and then placed a standard weight of 1.5 kg on the brush to measure the pressure as shown in Figure 5. The blocks were subjected to twelve similar cycles. The samples shown in Figure 5. The blocks were subjected to twelve similar cycles. The samples were as shown in Figure 5. The blocks were subjected to twelve similar cycles. The samples were then oven-dried and their ﬁnal weights were recorded. After 12 rounds of wett ing then oven-dried and their ﬁnal weights were recorded. After 12 rounds of wetting and were then oven-dried and their ﬁnal weights were recorded. After 12 rounds of wett ing and drying, the blocks were evaluated for their dry compressive strength and ﬂexural drying, the blocks were evaluated for their dry compressive strength and ﬂexural strength and drying, the blocks were evaluated for their dry compressive strength and ﬂexural strength to determine the performance. to determine the performance. strength to determine the performance. Figure 5. Measurement of pressure applied by wire scratch brush on the specimen. Figure 5. Measurement of pressure applied by wire scratch brush on the specimen. Figure 5. Measurement of pressure applied by wire scratch brush on the specimen. The weight of the block is measured immediately after demolding to determine how The weight of the block is measured immediately after demolding to determine how The weight of the block is measured immediately after demolding to determine how much moisture is present in the block. As the block dries, it loses moisture and its weight much moisture is present in the block. As the block dries, it loses moisture and its weight much moisture is present in the block. As the block dries, it loses moisture and its weight reduces. After the block was demolded, it was placed in a curing chamber or covered with reduces. After the block was demolded, it was placed in a curing chamber or covered with reduces. After the block was demolded, it was placed in a curing chamber or covered with a moist cloth to prevent the moisture from escaping too quickly. Curing is the process of a moist cloth to prevent the moisture from escaping too quickly. Curing is the process of a moist cloth to prevent the moisture from escaping too quickly. Curing is the process of keeping the block moist so that it can continue to gain strength and harden. The block is keeping the block moist so that it can continue to gain strength and harden. The block is keeping the block moist so that it can continue to gain strength and harden. The block is typically cured for 28 days, after which it reaches its maximum strength. Therefore, Figure 6 typically cured for 28 days, after which it reaches its maximum strength. Therefore, Figure typically cured for 28 days, after which it reaches its maximum strength. Therefore, Figure shows that the weight of the block was measured after demolding and after 28 days of 6 shows that the weight of the block was measured after demolding and after 28 days of 6 shows that the weight of the block was measured after demolding and after 28 days of curing to determine how much weight loss had occurred during the curing process. The curing to determine how much weight loss had occurred during the curing process. The curing to determine how much weight loss had occurred during the curing process. The weight loss is an indication of the moisture loss and the strength gain of the block. weight loss is an indication of the moisture loss and the strength gain of the block. weight loss is an indication of the moisture loss and the strength gain of the block. Buildings 2023, 13, x FOR PEER REVIEW 8 of 17 Buildings 2023, 13, 1114 8 of 17 (a) (b) (c) (d) (e) (f) Figure 6. Weight of block with various % of cement content (a) 0% cement, (b) 6% cement, (c) 7% Figure 6. Weight of block with various % of cement content (a) 0% cement, (b) 6% cement, (c) 7% ce- cement, (d) 8% cement, (e) 9% cement, (f) 10% cement. ment, (d) 8% cement, (e) 9% cement, (f) 10% cement. Buildings 2023, 13, x FOR PEER REVIEW 9 of 17 3. Results and Discussion 3.1. Mechanical Properties of Compressed Stabilized Earth Block 3.1.1. Dry and Wet Compressive Strength of Compressed Stabilized Earth Blocks The compressive strengths of CSEBs with and without MSWIBA were compared (dry and wet values taken after 28 days of curing, presented in Figure 7a,b). The dry and wet compressive strengths for the conventional earth blocks were, respectively, 3.50 and 1.68 MPa. In line with results from the literature, it was noted that the introduction of MSWIBA leads to a signiﬁcant enhancement in compressive strength when compared to the con- ventional earth block. The highest compressive strength was observed in the samples con- taining 10% cement, whereas the lowest compressive strength was noted in samples with- Buildings 2023, 13, 1114 9 of 17 out cement. Compressive strength improves with the cement content because of the stronger inter-particle connections from the cement hydration with the formation of cal- cium silicate hydrate (CSH) gels [43], binding the soil particles and ﬁlling the pores within 3. Results and Discussion the soil matrix. In addition, calcium aluminate silicate was formed when calcium hydrox- 3.1. Mechanical Properties of Compressed Stabilized Earth Block ide, a by-product of the crystallization of cement, reacts with the added MSWIBA [44]. In 3.1.1. Dry and Wet Compressive Strength of Compressed Stabilized Earth Blocks the CSEBs without cement content, the incorporation of MSWIBA does not have the same The compressive strengths of CSEBs with and without MSWIBA were compared (dry impact, and the strength of the system was not signiﬁcantly improved. An appropriate and wet values taken after 28 days of curing, presented in Figure 7a,b). The dry and quantity of MSWIBA must be added to the mixture in order to react with the hydrated wet compressive strengths for the conventional earth blocks were, respectively, 3.50 and product of cement crystallization. If the quantity of MSWIBA exceeds the required 1.68 MPa. In line with results from the literature, it was noted that the introduction of amount, the unreacted MSWIBA particles remain in the mixture, preventing the creation MSWIBA leads to a signiﬁcant enhancement in compressive strength when compared to the of strong interconnecting bonds with soil, thereby reducing the strength of the blocks. conventional earth block. The highest compressive strength was observed in the samples From the results, it was observed that the dry compressive strength values varied containing 10% cement, whereas the lowest compressive strength was noted in samples from 3.5 to 7.43 MPa and wet compressive strengths varied from 1.68 to 5.56 MPa, corre- without cement. Compressive strength improves with the cement content because of the sponding to 0–25% MSWIBA concentrations. The pozzolanic action and superior particle stronger inter-particle connections from the cement hydration with the formation of calcium size distribution of MSWIBA may be att ributed to this increase as reported by [45] and silicate hydrate (CSH) gels [43], binding the soil particles and ﬁlling the pores within the [44]. According to the standards, the wet strength should be over and above 0.7 MPa. The soil matrix. In addition, calcium aluminate silicate was formed when calcium hydroxide, dry compressive strength of the mixture containing 10% cement, and 15, 20 and 25% of a by-product of the crystallization of cement, reacts with the added MSWIBA [44]. In the MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while the wet compressive strengths CSEBs without cement content, the incorporation of MSWIBA does not have the same were, respectively, 4.10, 5.56 and 3.87 MPa. Superior strength was noted in the mixtures impact, and the strength of the system was not signiﬁcantly improved. An appropriate incorporating 10% cement and 20% MSWIBA. Figure 8 shows the wet-to-dry strength ra- quantity of MSWIBA must be added to the mixture in order to react with the hydrated tios for diﬀerent cement–MSWIBA combinations. It can be noted that the addition of an product of cement crystallization. If the quantity of MSWIBA exceeds the required amount, optimal quantity of MSWIBA to cement increases the wet-to-dry strength ratio, proving the unreacted MSWIBA particles remain in the mixture, preventing the creation of strong the need for stabilization. interconnecting bonds with soil, thereby reducing the strength of the blocks. (a) (b) Figure 7. (a) Dry compression strength and (b) wet compression strength varies with MSWIBA con- Figure 7. (a) Dry compression strength and (b) wet compression strength varies with MSWIBA centration. concentration. From the results, it was observed that the dry compressive strength values varied from 3.5 to 7.43 MPa and wet compressive strengths varied from 1.68 to 5.56 MPa, corre- sponding to 0–25% MSWIBA concentrations. The pozzolanic action and superior particle size distribution of MSWIBA may be attributed to this increase as reported by [44,45]. According to the standards, the wet strength should be over and above 0.7 MPa. The dry compressive strength of the mixture containing 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while the wet compressive strengths were, respectively, 4.10, 5.56 and 3.87 MPa. Superior strength was noted in the mixtures incorporating 10% cement and 20% MSWIBA. Figure 8 shows the wet-to-dry strength ratios for different cement–MSWIBA combinations. It can be noted that the addition of an optimal quantity of MSWIBA to cement increases the wet-to-dry strength ratio, proving the need for stabilization. Buildings 2023, 13, x FOR PEER REVIEW 10 of 17 Buildings 2023, 13, 1114 10 of 17 Figure 8. Wet-to-dry strength ratio. Figure 8. Wet-to-dry strength ratio. 3.1.2. Flexural Strength of Compressed Stabilized Earth Block 3.1.2. Flexural Strength of Compressed Stabilized Earth Block Figure 3 depicts the experimental setup for the ﬂexural test of CSEB and the results are Figure 3 depicts the experimental setup for the ﬂexural test of CSEB and the results shown in Figure 9. The conventional earth block exhibited a ﬂexural strength of 0.48 MPa. are shown in Figure 9. The conventional earth block exhibited a ﬂexural strength of 0.48 A progressive improvement in the ﬂexural strength may be noted with an increase in MPa. A progressive improvement in the ﬂexural strength may be noted with an increase the MSWIBA and cement content. The formation of cement hydration products and the Buildings 2023, 13, x FOR PEER REVIEW 11 of 17 in the MSWIBA and cement content. The formation of cement hydration products and the reaction with the MSWIBA help to improve the hydration cycle. Consequently, a greater reaction with the MSWIBA help to improve the hydration cycle. Consequently, a greater degree of bending resistance is provided by the soil matrix, which got tightly interconnected. degree of bending resistance is provided by the soil matrix, which got tightly intercon- The New Mexico [46] earthen building materials code recommends a minimum ﬂexural nected. The New Mexico [46] earthen building materials code recommends a minimum and 15, 20 and 25% of MSWIBA were, respectively, 12.4, 11.6 and 10.4%. The water ab- strength (in saturation) as 0.35 MPa, whereas the New Zealand Standard [47] and the Sri ﬂexural strength (in saturation) as 0.35 MPa, whereas the New Zealand Standard [47]and sorption of the specimen containing 7% cement was also comparable. These values were Lankan Standard [48] require stabilized earth bricks to have a ﬂexural strength above 0.25 the Sri Lankan Standard [48] require stabilized earth bricks to have a ﬂexural strength 12.8, 12.4 and 12.1%, respectively, at the MSWIBA content of 15, 20, and 25%. and 0.5 MPa, respectively [9]. above 0.25 and 0.5 MPa, respectively [9]. From the results, the ﬂexural strength of blocks comprising MSWIBA was higher than that of the conventional earth block. On average, the blocks had a ﬂexural strength of 26% to 28% of their compressive strength. The ﬂexural strengths of the mixture incor- porating 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 1.21, 1.32 and 0.83 MPa, as shown in Figure 9. Increasing MSWIBA from 10% to 20% increases the ﬂex- ural strength, on account of the pozzolanic activity and more uniform particle size distri- bution. The shape and roughness of MSWIBA, in addition to its pozzolanic action, are important factors in the development of strength. MSWIBA also acted as a connecting link between the cement–soil matrix, improving the performance. 3.1.3. Water Absorption of Compressed Stabilized Earth Block The stabilized earth blocks become less porous with age. After 28 days of curing, there was a notable reduction in water absorption across the board for all the blocks in- corporating 7–10% of cement. The chemical reaction of the cement with the alumino sili- cates in the soil generates cementitious products that bind soil particles together and so- lidify over time, minimizing void interconnectivity [14]. The water absorption of the con- ventional earth block was 14.4%. All the blocks exhibit water absorption varying between 10.2% to 14.4% at the end of the 28-day ageing period. With extended ageing, the water absorption values reduce considerably, as most of the specimens exhibited a water ab- Figure 9. Eﬀect of MSWIBA on the ﬂexural strength. Figure 9. Effect of MSWIBA on the ﬂexural strength. sorption far below the 15% maximum limit indicated by IS: 1725-2013 [33]. As shown in Figure 10, the water absorption of blocks improves with the increase in the quantity of From the results, the ﬂexural strength of blocks comprising MSWIBA was higher than cement and the MSWIBA. The water absorption of the mixture containing 10% cement, that of the conventional earth block. On average, the blocks had a ﬂexural strength of 26% Figure 10. Eﬀect of MSWIBA on the water absorption. 3.2. Alternate Wett ing–Drying The dry compressive strength of the mixture (at normal curing) containing 10% ce- ment and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while strengths were, respectively, 7.54, 7.98 and 6.43 MPa after the wett ing and drying cycles. A slight reduction in the compressive strength and ﬂexural strength was noted for the conventional earth block, following the wett ing–drying test, while an improvement in the strength may be noted for the specimen containing cement and MSWIBA. The gain in strength for the blocks containing 0% to 25% MSWIBA was in the range of 12–27% which Buildings 2023, 13, x FOR PEER REVIEW 11 of 17 Buildings 2023, 13, 1114 11 of 17 and 15, 20 and 25% of MSWIBA were, respectively, 12.4, 11.6 and 10.4%. The water ab- sorption of the specimen containing 7% cement was also comparable. These values were to 28% of their compressive strength. The ﬂexural strengths of the mixture incorporating 12.8, 12.4 and 12.1%, respectively, at the MSWIBA content of 15, 20, and 25%. 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 1.21, 1.32 and 0.83 MPa, as shown in Figure 9. Increasing MSWIBA from 10% to 20% increases the ﬂexural strength, on account of the pozzolanic activity and more uniform particle size distribution. The shape and roughness of MSWIBA, in addition to its pozzolanic action, are important factors in the development of strength. MSWIBA also acted as a connecting link between the cement–soil matrix, improving the performance. 3.1.3. Water Absorption of Compressed Stabilized Earth Block The stabilized earth blocks become less porous with age. After 28 days of curing, there was a notable reduction in water absorption across the board for all the blocks incorporating 7–10% of cement. The chemical reaction of the cement with the alumino silicates in the soil generates cementitious products that bind soil particles together and solidify over time, minimizing void interconnectivity [14]. The water absorption of the conventional earth block was 14.4%. All the blocks exhibit water absorption varying between 10.2% to 14.4% at the end of the 28-day ageing period. With extended ageing, the water absorption values reduce considerably, as most of the specimens exhibited a water absorption far below the 15% maximum limit indicated by IS: 1725-2013 [33]. As shown in Figure 10, the water absorption of blocks improves with the increase in the quantity of cement and the MSWIBA. The water absorption of the mixture containing 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 12.4, 11.6 and 10.4%. The water absorption of the specimen containing 7% cement was also comparable. These values were 12.8, 12.4 and Figure 9. Eﬀect of MSWIBA on the ﬂexural strength. 12.1%, respectively, at the MSWIBA content of 15, 20, and 25%. Figure 10. Eﬀect of MSWIBA on the water absorption. Figure 10. Effect of MSWIBA on the water absorption. 3.2. Alternate Wetting–Drying 3.2. Alternate Wett ing–Drying The dry compressive strength of the mixture (at normal curing) containing 10% cement The dry compressive strength of the mixture (at normal curing) containing 10% ce- and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while strengths ment and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while were, respectively, 7.54, 7.98 and 6.43 MPa after the wetting and drying cycles. A slight strengths were, respectively, 7.54, 7.98 and 6.43 MPa after the wett ing and drying cycles. reduction in the compressive strength and ﬂexural strength was noted for the conventional A slight reduction in the compressive strength and ﬂexural strength was noted for the earth block, following the wetting–drying test, while an improvement in the strength may conventional earth block, following the wett ing–drying test, while an improvement in the be noted for the specimen containing cement and MSWIBA. The gain in strength for the strength may be noted for the specimen containing cement and MSWIBA. The gain in blocks containing 0% to 25% MSWIBA was in the range of 12–27% which is mentioned in strength for the blocks containing 0% to 25% MSWIBA was in the range of 12–27% which Figure 11. Supplementary calcium silicate hydrate (CSH) gel was formed during the faster Buildings 2023, 13, x FOR PEER REVIEW 12 of 17 Buildings 2023, 13, x FOR PEER REVIEW 12 of 17 Buildings 2023, 13, 1114 12 of 17 is mentioned in Figure 11. Supplementary calcium silicate hydrate (CSH) gel was formed is mentioned in Figure 11. Supplementary calcium silicate hydrate (CSH) gel was formed during the faster hydration of the cement due to the pozzolanic reaction with MSWIBA at during the faster hydration of the cement due to the pozzolanic reaction with MSWIBA at 70 °C, which further enhanced the stiﬀness of the matrix [49]. Figure 12 shows the im- hydration of the cement due to the pozzolanic reaction with MSWIBA at 70 C, which 70 °C, which further enhanced the stiﬀness of the matrix [49]. Figure 12 shows the im- provement in ﬂexural strength of blocks after a series of wett ing–drying cycles. There was further enhanced the stiffness of the matrix [49]. Figure 12 shows the improvement in provement in ﬂexural strength of blocks after a series of wett ing–drying cycles. There was a notable improvement in the ﬂexural strength for the samples incorporating 10% cement ﬂexural strength of blocks after a series of wetting–drying cycles. There was a notable a notable improvement in the ﬂexural strength for the samples incorporating 10% cement and 10–25% MSWIBA. improvement in the ﬂexural strength for the samples incorporating 10% cement and and 10–25% MSWIBA. 10–25% MSWIBA. Figure 11. Dry compression strength of CSEB after alternate wett ing and drying. Figure 11. Dry compression strength of CSEB after alternate wetting and drying. Figure 11. Dry compression strength of CSEB after alternate wett ing and drying. Figure 12. Flexural strength of CSEB after alternate wett ing and drying. Figure 12. Flexural strength of CSEB after alternate wetting and drying. Figure 12. Flexural strength of CSEB after alternate wett ing and drying. 3.3. Stress–Strain Behavior of CSEB 3.3. Stress–Strain Behavior of CSEB 3.3. Stress–Strain Behavior of CSEB Dry and wet stress–strain behavior of CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, and 10% of cement, exhibited superior strength and durability. More straining was seen at lower stresses in the beginning for all CSEB samples. As strain Buildings 2023, 13, x FOR PEER REVIEW 13 of 17 Dry and wet stress–strain behavior of CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, and 10% of cement, exhibited superior strength and durability. More straining was seen at lower stresses in the beginning for all CSEB samples. As strain increases past the peak, the stress drops, and the CSEB specimens eventually fail. The strain values observed for the CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, and 10% of cement in the wet condition ranged between 0.02% and 0.18%. In contrast, for the dry state, the strain values were found to be higher, ranging between 0.24% and 1.10%. All the specimens showed a reduction in peak strain with time, with cement content and failure strain varying between 2.5% and 3.4%. An increase in cementi- Buildings 2023, 13, 1114 13 of 17 tious material–soil connections may lead to a stiﬀ axial response and a steep slope of axial stress–axial strain response. In Figure 13, peak stress and failure strain are greater for dry than wet samples. Stress–strain graphs are used to determine the initial tangent modulus increases past the peak, the stress drops, and the CSEB specimens eventually fail. The strain (ITM). The addition of various proportions of cement and MSWIBA resulted in a 40–50% values observed for the CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, rise in ITM, with a maximum value of 2.89 GPa. and 10% of cement in the wet condition ranged between 0.02% and 0.18%. In contrast, for In both the dry and wet phases, it is important to notice that the elastic modulus the dry state, the strain values were found to be higher, ranging between 0.24% and 1.10%. increased signiﬁcantly with an increase in cement percentage from 8% to 9%. Upon add- All the specimens showed a reduction in peak strain with time, with cement content and ing 8–10% of cement, the elastic modulus in the wet blocks increased between 19% and failure strain varying between 2.5% and 3.4%. An increase in cementitious material–soil 42% compared to 15% and 20% for dry CSEB specimens. Similar reactions were obtained connections may lead to a stiff axial response and a steep slope of axial stress–axial strain for 15% and 20% MSWIBA, emphasizing the necessity to utilize 9% cement rather than response. In Figure 13, peak stress and failure strain are greater for dry than wet samples. 10% cement when producing CSEB using MSWIBA. Overall structural ductility may be Stress–strain graphs are used to determine the initial tangent modulus (ITM). The addition assured by using cement-stabilized blocks with strong mortar joints between them and by of various proportions of cement and MSWIBA resulted in a 40–50% rise in ITM, with a increasing the integration between the block and the mortar. maximum value of 2.89 GPa. Buildings 2023, 13, x FOR PEER REVIEW 14 of 17 (a) (b) Figure 13. Stress–strain response of CSEB sample (a) 20% MSWIBA and (b) 25% MSWIBA. Figure 13. Stress–strain response of CSEB sample (a) 20% MSWIBA and (b) 25% MSWIBA. 3.4. Microstructural Analysis The scanning electron microscopy (SEM) images given on Figure 14 conﬁrm the per- formance of cement and MSWIBA materials. SEM was conducted on polished and gold- coated brick chips samples at a magniﬁcation of 5000×. Micrographs were captured using backscatt ered electrons and were viewed. An increase in the compressive strength of blocks with MSWIBA was observed on account of the bett er ﬁlling when compared to the conventional earth block. The internal phase of the compressed stabilized earth block con- taining 10% cement with 20% MSWIBA exhibits a higher density and fewer voids in com- parison to the compressed stabilized earth block containing 10% cement with 15% and 25% MSWIBA, as depicted in Figure 14. The C-S-H gel formation in transition zone ap- pears to be superior in the specimen incorporating 10% of cement with 20% of MSWIBA, and it had a maximum compressive strength of 7.43 MPa. (a) (b) (c) Figure 14. SEM analysis, (a) 10% of cement with 15% of MSWIBA, (b) 10% of cement with 25% of MSWIBA, (c) 10% of cement with 20% of MSWIBA. 3.5. Cost Analysis The cost to construct a typical room, measuring 6 m× 3 m× 3 m, is calculated. In the design, a wall thickness of 0.3 m is considered, with three windows measuring 1.2 m × 1.2 m, and one door with dimension 1.2 m × 2.1 m. Figure 15 illustrates the structure as seen from the plan view perspective. The CSEB blocks have dimensions of 240 mm × 115 mm Buildings 2023, 13, x FOR PEER REVIEW 14 of 17 Buildings 2023, 13, 1114 14 of 17 In both the dry and wet phases, it is important to notice that the elastic modulus increased signiﬁcantly with an increase in cement percentage from 8% to 9%. Upon adding 8–10% of cement, the elastic modulus in the wet blocks increased between 19% and 42% compared to 15% and 20% for dry CSEB specimens. Similar reactions were obtained for 15% and 20% MSWIBA, emphasizing the necessity to utilize 9% cement rather than 10% cement when producing CSEB using MSWIBA. (b) Overall structural ductility may be assured by using cement-stabilized blocks with strong mortar joints between them and by increasing Figure 13. Stress–strain response of CSEB sample (a) 20% MSWIBA and (b) 25% MSWIBA. the integration between the block and the mortar. 3.4. Microstructural Analysis 3.4. Microstructural Analysis The scanning electron microscopy (SEM) images given on Figure 14 conﬁrm the per- The scanning electron microscopy (SEM) images given on Figure 14 conﬁrm the formance of cement and MSWIBA materials. SEM was conducted on polished and gold- performance of cement and MSWIBA materials. SEM was conducted on polished and coated brick chips samples at a magniﬁcation of 5000×. Micrographs were captured using gold-coated brick chips samples at a magniﬁcation of 5000. Micrographs were captured backscatt ered electrons and were viewed. An increase in the compressive strength of using backscattered electrons and were viewed. An increase in the compressive strength blocks with MSWIBA was observed on account of the bett er ﬁlling when compared to the of blocks with MSWIBA was observed on account of the better ﬁlling when compared to conventional earth block. The internal phase of the compressed stabilized earth block con- the conventional earth block. The internal phase of the compressed stabilized earth block taining 10% cement with 20% MSWIBA exhibits a higher density and fewer voids in com- containing 10% cement with 20% MSWIBA exhibits a higher density and fewer voids in parison to the compressed stabilized earth block containing 10% cement with 15% and comparison to the compressed stabilized earth block containing 10% cement with 15% and 25% MSWIBA, as depicted in Figure 14. The C-S-H gel formation in transition zone ap- 25% MSWIBA, as depicted in Figure 14. The C-S-H gel formation in transition zone appears pears to be superior in the specimen incorporating 10% of cement with 20% of MSWIBA, to be superior in the specimen incorporating 10% of cement with 20% of MSWIBA, and it and it had a maximum compressive strength of 7.43 MPa. had a maximum compressive strength of 7.43 MPa. (a) (b) (c) Figure 14. SEM analysis, (a) 10% of cement with 15% of MSWIBA, (b) 10% of cement with 25% of Figure 14. SEM analysis, (a) 10% of cement with 15% of MSWIBA, (b) 10% of cement with 25% of MSWIBA, (c) 10% of cement with 20% of MSWIBA. MSWIBA, (c) 10% of cement with 20% of MSWIBA. 3.5. Cost Analysis 3.5. Cost Analysis The cost to construct a typical room, measuring 6 m× 3 m× 3 m, is calculated. In the The cost to construct a typical room, measuring 6 m 3 m 3 m, is calculated. desi In the gn, a design, wall th aickness o wall thickness f 0.3 m is con of 0.3sm idered, w is conside ith t rh ed, ree window with three s m windows easuring 1 measuring .2 m × 1.2 m 1.2 , and on m 1.2 e dm, oor wit and h one dim door ension with 1.2dimension m × 2.1 m. Fi 1.2 gur me 152.1 illum. straFigur tes the e st 15ruct illustrates ure as seen the from the plan structure as seen view perspe from thectiv plan e. The CSEB view perspective. blocks hav The e dimensio CSEB blocks ns of have 240 m dimensions m × 115 mm of 240 mm 115 mm 90 mm (MSWIBA–cement) and 240 mm 120 mm 90 mm (sand– cement), and an approximate unit weight of 1850 kg/m . To manufacture 3900 earthen blocks, the estimated quantity of cement is 1300 kg and MSWIBA is 2900 kg. The Indian standard rates were utilized for all the costs of materials in this investigation, and the projected cost is estimated as USD 750. Modern construction practices employ CSEBs in the form of interlocking blocks, which signiﬁcantly minimizes the need for mortar and the associated cost. In addition, due to the added transportation expenses, the total cost of the CSEB was signiﬁcantly greater than the typical concrete block. For building an identical room using ﬁred clay bricks (FCBs), the total cost may be computed as USD 809 [27], while the overall construction cost for sand–cement-stabilized CSEBs is projected to be USD 862 [27]. The cost comparison reveals that utilizing CSEBs stabilized with MSWIBA might reduce the total construction costs by 8% compared to the price of FCBs and by 13% when compared to the price of CSEBs stabilized with cement and sand. MSWIBA and cement-stabilized CSEBs are therefore a cost-efﬁcient option. Buildings 2023, 13, x FOR PEER REVIEW 15 of 17 × 90 mm (MSWIBA–cement) and 240 mm × 120 mm × 90 mm (sand–cement), and an ap- proximate unit weight of 1850 kg/m . To manufacture 3900 earthen blocks, the estimated quantity of cement is 1300 kg and MSWIBA is 2900 kg. The Indian standard rates were utilized for all the costs of materials in this investigation, and the projected cost is esti- mated as USD 750. Modern construction practices employ CSEBs in the form of interlock- ing blocks, which signiﬁcantly minimizes the need for mortar and the associated cost. In addition, due to the added transportation expenses, the total cost of the CSEB was signif- icantly greater than the typical concrete block. For building an identical room using ﬁred clay bricks (FCBs), the total cost may be computed as USD 809 [27], while the overall con- struction cost for sand–cement-stabilized CSEBs is projected to be USD 862 [27]. The cost comparison reveals that utilizing CSEBs stabilized with MSWIBA might reduce the total construction costs by 8% compared to the price of FCBs and by 13% when compared to Buildings 2023, 13, 1114 15 of 17 the price of CSEBs stabilized with cement and sand. MSWIBA and cement-stabilized CSEBs are therefore a cost-eﬃcient option. (a) (b) Figure 15. Cost analysis. (a) Plan and (b) perspective view. Figure 15. Cost analysis. (a) Plan and (b) perspective view. 4. Conclusions 4. Conclusions This study evaluated the application of municipal solid waste incinerator bottom This study evaluated the application of municipal solid waste incinerator bott om ash ash (MSWIBA) to partially replace ﬁne aggregate and ordinary Portland cement (OPC) as (MSWIBA) to partially replace ﬁne aggregate and ordinary Portland cement (OPC) as sta- stabilizers in compressed earth blocks (CEBs). The amount of cement binder added to the bilizers in compressed earth blocks (CEBs). The amount of cement binder added to the mix varied from 0% to 10%. Additionally, a portion of the sand was replaced with MSWIBA mix varied from 0% to 10%. Additionally, a portion of the sand was replaced with in varying amounts ranging from 0% to 25%. This replacement of sand with MSWIBA MSWIBA in varying amounts ranging from 0% to 25%. This replacement of sand with resulted in a corresponding decrease in the sand content, which varied from 70% to 45% MSWIBA resulted in a corresponding decrease in the sand content, which varied from depending on the speciﬁc amount of MSWIBA added to the mix. An assessment was 70% to 45% depending on the speciﬁc amount of MSWIBA added to the mix. An assess- conducted to determine the strength and durability of compressed stabilized earth blocks ment was conducted to determine the strength and durability of compressed stabilized (CSEBs). This included evaluating the compressive strength in dry and wet conditions, earth blocks (CSEBs). This included evaluating the compressive strength in dry and wet ﬂexural strength, water absorption, and analyzing their behavior during alternate wetting conditions, ﬂexural strength, water absorption, and analyzing their behavior during alter- and drying, as well as their stress–strain behavior and microstructure. Based on the nate wett ing and drying, as well as their stress–strain behavior and microstructure. Based ﬁndings of this investigation, the addition of cement increases the mechanical and durability on the ﬁndings of this investigation, the addition of cement increases the mechanical and characteristics of the compressed earth blocks. The optimal quantity of MSWIBA was noted durability characteristics of the compressed earth blocks. The optimal quantity of as 15% for 6–7% cement and 20% for 10% cement content, while the optimal mix proportion MSWIBA was noted as 15% for 6–7% cement and 20% for 10% cement content, while the may vary depending on the type of cement and MSWIBA. If the cement and MSWIBA optimal mix proportion may vary depending on the type of cement and MSWIBA. If the content exceeds the optimal level, there could be a marginal reduction in strength and a rise cement and MSWIBA content exceeds the optimal level, there could be a marginal reduc- in water absorption. The cost of CSEBs stabilized with cement and MSWIBA was reduced by tion in strength and a rise in water absorption. The cost of CSEBs stabilized with cement 8–13% when compared with the earthen blocks stabilized with a cement–sand combination, and MSWIBA was reduced by 8–13% when compared with the earthen blocks stabilized demonstrating the economic advantage of cement–MSWIBA-stabilized CSEBs. with a cement–sand combination, demonstrating the economic advantage of cement– The utilization of bottom ash obtained from municipal solid waste incinerators in MSWIBA-stabilized CSEBs. the production of compressed stabilized earth blocks has the potential to maintain the The utilization of bott om ash obtained from municipal solid waste incinerators in the mechanical and durability properties of the blocks. Nevertheless, further research is production of compressed stabilized earth blocks has the potential to maintain the me- necessary to analyze the long-term performance, such as ageing tests, and ﬁeld studies chanical and durability properties of the blocks. Nevertheless, further research is neces- should be conducted to evaluate the performance of MSWIBA-stabilized CSEBs in different sary to analyze the long-term performance, such as ageing tests, and ﬁeld studies should climatic conditions and soil types. Author Contributions: Conceptualization, A.T.L. and B.M.; methodology, A.T.L. and B.M.; software, A.T.L., B.M. and B.S.T.; validation, A.T.L., B.M. and B.S.T.; formal analysis, A.T.L., B.M. and B.S.T.; investigation, A.T.L., B.M. and B.S.T.; resources, A.T.L., B.M. and B.S.T.; data curation, A.T.L., B.M. and B.S.T.; writing—original draft preparation, A.T.L., B.M. and B.S.T.; writing—review and editing, A.T.L., B.M. and B.S.T.; visualization, A.T.L., B.M. and B.S.T.; supervision, A.T.L. and B.M.; project administration, A.T.L., B.M. and B.S.T. All authors have read and agreed to the published version of the manuscript. Funding: This research did not receive any funding from any other sources. Data Availability Statement: This does not apply. Conﬂicts of Interest: The authors state that there is no conﬂict of interest in relation to the publication of this research. Buildings 2023, 13, 1114 16 of 17 References 1. Chauhan, P.; El Hajjar, A.; Prime, N.; Plé, O. Unsaturated behavior of rammed earth: Experimentation towards numerical modelling. Constr. Build. Mater. 2019, 227, 116646. [CrossRef] 2. Brito, M.R.; Marvila, M.T.; Linhares, J.A.T., Jr.; Azevedo, A.R.G.D. Evaluation of the Properties of Adobe Blocks with Clay and Manure. Buildings 2023, 13, 657. [CrossRef] 3. Lahdili, M.; El Abbassi, F.-E.; Sakami, S.; Aamouche, A. Mechanical and Thermal Behavior of Compressed Earth Bricks Reinforced with Lime and Coal Aggregates. Buildings 2022, 12, 1730. [CrossRef] 4. Binici, H.; Aksogan, O.; Shah, T. Investigation of ﬁbre reinforced mud brick as a building material. Constr. Build. Mater. 2005, 19, 313–318. [CrossRef] 5. Rovnaník, P.; Rovnaníková, P. Blended alkali-activated ﬂy ash/brick powder materials. Procedia Eng. 2016, 151, 108–113. [CrossRef] 6. Naganathan, S.; Yousef, A.; Mohamed, O.; Mustapha, K.N. Performance of bricks made using ﬂy ash and bottom ash. Constr. Build. Mater. 2015, 96, 576–580. [CrossRef] 7. Shariful, M.; Elahi, T.E.; Rafat, A.; Mumtaz, N. Effectiveness of ﬂy ash and cement for compressed stabilized earth block construction. Constr. Build. Mater. 2020, 255, 119392. 8. Elahi, T.E.; Rafat, A.; Shariful, M.; Mehzabin, F. Suitability of ﬂy ash and cement for fabrication of compressed stabilized earth blocks. Constr. Build. Mater. 2020, 263, 120935. [CrossRef] 9. Elahi, T.E.; Rafat, A.; Shariful, M. Engineering characteristics of compressed earth blocks stabilized with cement and ﬂy ash. Constr. Build. Mater. 2021, 277, 122367. [CrossRef] 10. Prashanth, R.; Selvan, S.S.; Balasubramanian, M. Experimental Investigation on Durability Properties of Concrete Added with Nano Silica. Rasayan J. Chem. 2019, 12, 685–690. [CrossRef] 11. Sekhar, D.C.; Nayak, S. Utilization of granulated blast furnace slag and cement in the manufacture of compressed stabilized earth blocks. Constr. Build. Mater. 2018, 166, 531–536. [CrossRef] 12. Nagaraj, H.; Shreyasvi, C. Compressed Stabilized Earth Blocks Using Iron Mine Spoil Waste—An Explorative Study. Procedia Eng. 2017, 180, 1203–1212. [CrossRef] 13. Contreras, M.; Teixeira, S.R.; Lucas, M.C.; Lima, L.C.N.; Cardoso, D.S.L.; da Silva, G.A.C.; Gregório, G.C.; de Souza, A.E.; dos Santos, A. Recycling of construction and demolition waste for producing new construction material (Brazil case-study). Constr. Build. Mater. 2016, 123, 594–600. [CrossRef] 14. Hb, N.; Kv, A.; Nc, D. Utilization of granite sludge in the preparation of durable compressed stabilized earth blocks. MOJ Civ. Eng. 2018, 4, 237–243. [CrossRef] 15. Choi, W.; Jeon, C. Development and performance veriﬁcation of quality improvement equipment for recycled ﬁne aggregate and soil. J. Mater. Cycles Waste Manag. 2021, 23, 1331–1347. [CrossRef] 16. Agamuthu, P.; Victor, D. Policy Evolution of Solid Waste Management in Malaysia. J. Mater. Cycles Waste Manag. 2009, 11, 916–924. 17. Ouedraogo, K.; Aubert, J.; Tribout, C.; Millogo, Y.; Escadeillas, G. Ovalbumin as natural organic binder for stabilizing unﬁred earth bricks: Understanding vernacular techniques to inspire modern constructions. J. Cult. Heritage 2021, 50, 139–149. [CrossRef] 18. Banerjee, R.; Goswami, P.; Mukherjee, A. Stabilization of iron ore mine spoil dump sites with vetiver system. In Bio-Geotechnologies for Mine Site Rehabilitation; Elsevier: Amsterdam, The Netherlands, 2018; pp. 393–413. 19. Kasinikota, P.; Tripura, D.D. Evaluation of compressed stabilized earth block properties using crushed brick waste. Constr. Build. Mater. 2021, 280, 122520. [CrossRef] 20. Turco, C.; Junior, A.C.P.; Teixeira, E.R.; Mateus, R. Optimisation of Compressed Earth Blocks (CEBs) using natural origin materials: A systematic literature review. Constr. Build. Mater. 2021, 309, 125140. [CrossRef] 21. Muntohar, A.S. Engineering characteristics of the compressed-stabilized earth brick. Constr. Build. Mater. 2011, 25, 4215–4220. [CrossRef] 22. Haiying, Z.; Youcai, Z.; Jingyu, Q. Utilization of municipal solid waste incineration (MSWI) ﬂy ash in ceramic brick: Product characterization and environmental toxicity. Waste Manag. 2011, 31, 331–341. [CrossRef] [PubMed] 23. Silva, R.V.; De Brito, J.; Lynn, C.J.; Dhir, R.K. Use of municipal solid waste incineration bottom ashes in alkali- activated materials, ceramics and granular applications: A review. Waste Manag. 2017, 68, 207–220. [CrossRef] 24. Chen, D.M. The world’ s growing municipal solid waste: Trends and impacts The world’ s growing municipal solid waste: Trends and impacts. Environ. Res. Lett. 2020, 15, 74021. [CrossRef] 25. Jesudass, A.; Gayathri, V.; Geethan, R.; Gobirajan, M.; Venkatesh, M. Earthen blocks with natural ﬁbres—A review. Mater. Today Proc. 2021, 45, 6979–6986. [CrossRef] 26. Rahla, K.M.; Mateus, R.; Bragança, L. Implementing Circular Economy Strategies in Buildings—From Theory to Practice. Appl. Syst. Innov. 2021, 4, 26. [CrossRef] 27. Islam, M.S.; Elahi, T.E.; Shahriar, A.R.; Nahar, K.; Hossain, T.R. Strength and Durability Characteristics of Cement-Sand Stabilized Earth Blocks. J. Mater. Civ. Eng. 2020, 32. [CrossRef] 28. Oti, J.; Kinuthia, J.; Bai, J. Engineering properties of unﬁred clay masonry bricks. Eng. Geol. 2009, 107, 130–139. [CrossRef] 29. SP-36 (Part1); Compendium of Indian Standards on Soil Engineering: Lab Testing of soils for Civil Engineering purposes. Bureau of Indian Standards: New Delhi, India, 1987. Buildings 2023, 13, 1114 17 of 17 30. Concrete, G.; Block, I.; Agricultural, F. Investigation of compressed earth brick containing ceramic waste investigation of compressed earth brick containing. ARPN J. Eng. Appl. Sci. 2016, 11, 5459–5462. 31. Nagaraj, H.; Rajesh, A.; Sravan, M. Inﬂuence of soil gradation, proportion and combination of admixtures on the properties and durability of CSEBs. Constr. Build. Mater. 2016, 110, 135–144. [CrossRef] 32. AS HB 195; The Australian Earth Building Handbook. Standard Australia: Sydney, Australia, 2002. 33. IS: 1725; Speciﬁcation for soil based blocks used in general building construction. Bureau of Indian Standards: New Delhi, India, 34. Teerajetgul, W.; Sinthaworn, S. Effects of Using Fine Quarry Waste as Cement Replacement Material on the Compressive Strength of the Mixture of Interlocking Block. Adv. Mater. Res. 2014, 1032, 2348–2353. [CrossRef] 35. Bahar, R.; Benazzoug, M.; Kenai, S. Performance of compacted cement-stabilised soil. Cem. Concr. Compos. 2004, 26, 811–820. [CrossRef] 36. Tripura, D.D.; Singh, K.D. Characteristic Properties of Cement-Stabilized Rammed Earth Blocks. J. Mater. Civ. Eng. 2015, 27, 1–8. [CrossRef] 37. Balkis, A.P. The effects of waste marble dust and polypropylene ﬁber contents on mechanical properties of gypsum stabilized earthen. Constr. Build. Mater. 2017, 134, 556–562. [CrossRef] 38. IS:3495-Part1; Methods of Tests of Burnt Clay Building Bricks. Bureau of Indian Standards: New Delhi, India, 1992. 39. IS 5454; Methods for Sampling of Clay Building Bricks. Bureau of Indian Standards: New Delhi, India, 1978. 40. Chou, M.-I.M.; Patel, V.; Laird, C.J.; Ho, K.K. Chemical and Engineering Properties of Fired Bricks Containing 50 Weight Percent of Class F Fly Ash. Energy Sources 2001, 23, 665–673. [CrossRef] 41. ASTM C 67-02c; Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile. Annual Book of ASTM Standards: Conshohocken, PA, USA, 2002. 42. ASTM D 559-03; Test Methods for Wetting and Drying Compacted Soil–Cement Mixtures. Annual Book of ASTM Standards: Conshohocken, PA, USA, 2003. 43. Gandia, R.M.; Gomes, F.C.; Aparecida, A.; Corrêa, R.; Rodrigues, M.C.; Mendes, R.F. Physical, mechanical and thermal behavior of adobe stabilized with glass ﬁber reinforced polymer waste. Constr. Build. Mater. 2019, 222, 168–182. [CrossRef] 44. Seco, A.; Omer, J.; Marcelino, S.; Espuelas, S.; Prieto, E. Sustainable unﬁred bricks manufacturing from construction and demolition wastes. Constr. Build. Mater. 2018, 167, 154–165. [CrossRef] 45. Oti, J.E.; Kinuthia, J.M.; Robinson, R.B. Applied Clay Science The development of un ﬁ red clay building material using Brick Dust Waste and Mercia mudstone clay. Appl. Clay Sci. 2014, 102, 148–154. [CrossRef] 46. New Mexico Earthen Building Materials Code; New Mexico Administrative: Santa Fe, NM, USA, 2011; pp. 1–28. 47. NZS 4298; Materials and Workmanship for Earth Buildings (Building Code Compliance Document E2). Standards New Zealand: Wellington, New Zealand, 1998; Volume 4298. 48. UN-Habitat Sri Lanka Sustainable Construction Using Alternative Technologies Compressed Stabilized Earth Blocks (CSEB) for Wall Construction. 2015. Available online: https://unhabitat.lk/wp-content/uploads/2016/04/Compressed-Stabilized-Earth- Blocks-CSEB-for-Wall-Construction.pdf (accessed on 3 April 2014). 49. Hallal, M.M.; Sadek, S.; Najjar, S.S. Evaluation of Engineering Characteristics of Stabilized Rammed-Earth Material Sourced from Natural Fines-Rich Soil. J. Mater. Civ. Eng. 2018, 30, 4018273. [CrossRef] Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). 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References (39)

Chiara Turco, Adilson Junior, E. Teixeira, R. Mateus (2021)
Optimisation of Compressed Earth Blocks (CEBs) using natural origin materials: A systematic literature review
Construction and Building Materials
Tausif Elahi, A. Shahriar, M. Islam (2021)
Engineering characteristics of compressed earth blocks stabilized with cement and fly ash
Construction and Building Materials, 277
A. Jesudass, Voorandoori Gayathri, R. Geethan, M. Gobirajan, M. Venkatesh (2021)
Earthen blocks with natural fibres - A review
Materials Today: Proceedings
Nagaraj Hb, An, Kv, D. Nc (2018)
Utilization of granite sludge in the preparation of durable compressed stabilized earth blocks
, 4
Kamel Rahla, R. Mateus, L. Bragança (2021)
Implementing Circular Economy Strategies in Buildings—From Theory to Practice
, 4
M. Hallal, S. Sadek, S. Najjar (2018)
Evaluation of Engineering Characteristics of Stabilized Rammed-Earth Material Sourced from Natural Fines-Rich Soil
Journal of Materials in Civil Engineering
Concrete (2016)
Investigation of compressed earth brick containing ceramic waste investigation of compressed earth brick containing
ARPN J. Eng. Appl. Sci., 11
David Chen, B. Bodirsky, T. Krueger, Abhijeet Mishra, A. Popp (2020)
The world’s growing municipal solid waste: trends and impacts
Environmental Research Letters, 15
R. Silva, J. Brito, C. Lynn, R. Dhir (2017)
Use of municipal solid waste incineration bottom ashes in alkali-activated materials, ceramics and granular applications: A review.
Waste management, 68
R. Bahar, M. Benazzoug, S. Kenai (2004)
Performance of compacted cement-stabilised soil
Cement & Concrete Composites, 26
Marina Brito, M. Marvila, José Linhares, A. Azevedo (2023)
Evaluation of the Properties of Adobe Blocks with Clay and Manure
Buildings
P. Chauhan, A. Hajjar, N. Prime, O. Plé (2019)
Unsaturated behavior of rammed earth: Experimentation towards numerical modelling
Construction and Building Materials, 227
H. Binici, O. Aksogan, T. Shah (2005)
Investigation of fibre reinforced mud brick as a building material
Construction and Building Materials, 19
R. Prashanth, S. Selvan, M. Balasubramanian (2019)
EXPERIMENTAL INVESTIGATION ON DURABILITY PROPERTIES OF CONCRETE ADDED WITH NANO SILICA
Rasayan Journal of Chemistry
A. Seco, J. Omer, S. Marcelino, S. Espuelas, E. Prieto (2018)
Sustainable unfired bricks manufacturing from construction and demolition wastes
Construction and Building Materials, 167
H. Nagaraj, A. Rajesh, M. Sravan (2016)
Influence of soil gradation, proportion and combination of admixtures on the properties and durability of CSEBs
Construction and Building Materials, 110
D. Tripura, K. Singh (2015)
Characteristic Properties of Cement-Stabilized Rammed Earth Blocks
Journal of Materials in Civil Engineering, 27
M. Islam, Tausif Elahi, A. Shahriar, Nashid Mumtaz (2020)
Effectiveness of fly ash and cement for compressed stabilized earth block construction
Construction and Building Materials, 255
A. Balkis (2017)
The effects of waste marble dust and polypropylene fiber contents on mechanical properties of gypsum stabilized earthen
Construction and Building Materials, 134
Won-Young Choi, Chansoo Jeon (2021)
Development and performance verification of quality improvement equipment for recycled fine aggregate and soil
Journal of Material Cycles and Waste Management, 23
M. Chou, V. Patel, Charles Laird, K. Ho (2001)
Chemical and engineering properties of fired bricks containing 50 weight percent of class F fly ash
Energy Sources, 23
P. Rovnaník, B. Řezník, P. Rovnaníková (2016)
Blended Alkali-activated Fly Ash / Brick Powder Materials☆
Procedia Engineering, 151
K. Ouedraogo, J. Aubert, C. Tribout, Y. Millogo, G. Escadeillas (2021)
Ovalbumin as natural organic binder for stabilizing unfired earth bricks: Understanding vernacular techniques to inspire modern constructions
Journal of Cultural Heritage
D. Sekhar, S. Nayak (2018)
Utilization of granulated blast furnace slag and cement in the manufacture of compressed stabilized earth blocks
Construction and Building Materials, 166
Tausif Elahi, A. Shahriar, M. Islam, Farzana Mehzabin, Nashid Mumtaz (2020)
Suitability of fly ash and cement for fabrication of compressed stabilized earth blocks
Construction and Building Materials, 263
J. Oti, J. Kinuthia, Jiping Bai (2009)
Engineering properties of unfired clay masonry bricks
Engineering Geology, 107
J. Oti, J. Kinuthia, R. Robinson (2014)
The development of unfired clay building material using Brick Dust Waste and Mercia mudstone clay
Applied Clay Science, 102
A. Muntohar (2011)
Engineering characteristics of the compressed-stabilized earth brick
Construction and Building Materials, 25
Pardhasaradhi Kasinikota, D. Tripura (2021)
Evaluation of compressed stabilized earth block properties using crushed brick waste
Construction and Building Materials, 280
10.1061/(ASCE)MT.1943-5533.0003176
Wasan Teerajetgul, S. Sinthaworn (2014)
Effects of Using Fine Quarry Waste as Cement Replacement Material on the Compressive Strength of the Mixture of Interlocking Block
Advanced Materials Research, 1030-1032
Mohamed Lahdili, Fatima-Ezzahra Abbassi, Siham Sakami, A. Aamouche (2022)
Mechanical and Thermal Behavior of Compressed Earth Bricks Reinforced with Lime and Coal Aggregates
Buildings
P. Agamuthu, D. Victor (2011)
Policy evolution of solid waste management in Malaysia
Haiying Zhang, Youcai Zhao, J. Qi (2011)
Utilization of municipal solid waste incineration (MSWI) fly ash in ceramic brick: product characterization and environmental toxicity.
Waste management, 31 2
R. Gandia, F. Gomes, A. Corrêa, Maykmiller Rodrigues, R. Mendes (2019)
Physical, mechanical and thermal behavior of adobe stabilized with glass fiber reinforced polymer waste
Construction and Building Materials
S. Naganathan, Almamon Mohamed, K. Mustapha (2015)
Performance of bricks made using fly ash and bottom ash
Construction and Building Materials, 96
Noorwirdawati Ali, Kharina Yaacob, M. Burhanudin, S. Shahidan, S. Abdullah (2015)
INVESTIGATION OF COMPRESSED EARTH BRICK CONTAINING CERAMIC WASTE
H. Nagaraj, C. Shreyasvi (2017)
Compressed Stabilized Earth Blocks Using Iron Mine Spoil Waste - An Explorative Study
Procedia Engineering, 180
M. Contreras, S. Teixeira, M. Lucas, L. Lima, D. Cardoso, G.A.C. Silva, G. Gregório, A. Souza, A. Santos (2016)
Recycling of construction and demolition waste for producing new construction material (Brazil case-study)
Construction and Building Materials, 123

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Abstract

buildings Article Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates 1 2 , 3 Abinaya Thennarasan Latha , Balasubramanian Murugesan * and Blessen Skariah Thomas School of Architecture and Interior Design, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India; abinayat@srmist.edu.in Department of Civil Engineering, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India Department of Civil Engineering, National Institute of Technology, Calicut 673601, Kerala, India; blessen@nitc.ac.in * Correspondence: balasubm1@srmist.edu.in Abstract: This research explores the potential of using municipal solid waste incinerator bottom ash (MSWIBA) as a partial replacement for ﬁne aggregate and ordinary Portland cement (OPC) as a stabilizer in the production of compressed stabilized earth blocks (CSEBs). The study investigates the effect of varying levels of cement content (ranging from 0% to 10%) and MSWIBA content (ranging from 0% to 25%) on the strength and durability of CSEBs. The strength characteristics of CSEBs were evaluated through tests such as wet and dry compressive strength, ﬂexural strength, water absorption, and stress–strain behavior, while durability was tested through wetting–drying cyclic tests. The results indicated that CSEB blocks made with 20% MSWIBA content and 10% cement were able to fulﬁll strength criteria. Additionally, using these blocks could result in cost savings of 8% during construction when compared to using ﬁred clay bricks (FCB). Furthermore, varying the cement content while maintaining a constant proportion of MSWIBA showed a signiﬁcant change in the stress–strain behavior and a cost analysis performed for CSEBs stabilized with the optimal quantity of MSWIBA-OPC combination showed that they can be a viable alternative to conventional earth Citation: Thennarasan Latha, A.; blocks, providing an eco-friendly, sustainable, and cost-effective solution for construction initiatives. Murugesan, B.; Thomas, B.S. Compressed Stabilized Earth Block Keywords: municipal solid waste incinerator bottom ash; sustainable cementitious material; Incorporating Municipal Solid Waste compressed stabilized earth blocks; microstructure Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates. Buildings 2023, 13, 1114. https:// doi.org/10.3390/buildings13051114 1. Introduction Academic Editor: Haoxin Li Soil has been one of the primary construction elements for thousands of years. More than a third of the world’s inhabitants are still living in soil dwellings. In the UK, around Received: 18 March 2023 half a million earth houses were constructed before the 1900s and are still standing [1,2]. Revised: 16 April 2023 Nearly two-thirds of all homes in India are still constructed using soil [3,4]. Generally, Accepted: 19 April 2023 in regions where the climate is hot and dry, and rain is scarce, earth has been utilized Published: 22 April 2023 extensively for building houses [5]. Earth structures are becoming more popular nowadays because of their various environmental advantages, including low energy intensity, reduced CO emissions, recycling capacity and the potential to serve as a buffer to manage humidity Copyright: © 2023 by the authors. inside the house. Concrete blocks and burned clay bricks have been observed to emit 200 kg Licensee MDPI, Basel, Switzerland. of CO per ton and 143 kg of CO per ton, respectively [6,7]. More importantly, cement 2 2 This article is an open access article manufacturing generates huge quantities of greenhouse gases, and an estimated quantity distributed under the terms and of 5% of annual production of carbon dioxide is because of cement production [8,9]. conditions of the Creative Commons The usage of earth as a construction material is becoming more prevalent nowadays. Attribution (CC BY) license (https:// Fired clay bricks are often used in masonry walls, but their high energy consumption and creativecommons.org/licenses/by/ carbon dioxide emissions make them unsuitable, in addition to the growing energy cost and 4.0/). Buildings 2023, 13, 1114. https://doi.org/10.3390/buildings13051114 https://www.mdpi.com/journal/buildings Buildings 2023, 13, 1114 2 of 17 other associated environmental issues. Stabilized unﬁred clay bricks may be a sustainable solution for these issues. There are several techniques for making earth bricks, with adobe and compressed earth bricks (CEB) being the most common. Of these, CEB has proven to be particularly advantageous due to its low cost, durability, and eco-friendliness [3]. In this study, conventional earth blocks (CSB) were also considered. Compression is used to create sustainable bricks with good mechanical properties. However, not all soils are suitable for making CEB, and many researchers have resorted to modifying the soil by adding stabilizers, binders, or both [3]. This is necessary because the soil must meet speciﬁc requirements for CEB manufacturing, which may not be available in many cases. Stabilized earth seems to stand out among the environmentally friendly building materials [10]. Over the last ﬁfty years, compressed stabilized earth blocks (CSEB) have been used for load- bearing masonry construction in various countries such as the USA, India, the UK, Brazil, Nigeria, etc. [11]. These blocks are made by pressing wet soil and an appropriate stabilizer into a high-density block with the aid of a manually operated press [12]. Environmentally friendly CSEBs possess high strength and durability with excellent thermal insulation capabilities [13]. When compared to CSEBs stabilized with lime, cement- stabilized CSEBs have better strength and durability [14]. At a cement content above 4%, CSEBs beneﬁt from increased strength and durability [15]. At 10% cement, the strength has been observed to be twice that of 4% cement, and the quantity of cement varies with the nature of soil. A cement content above 15% has been considered uneconomical [16]. The increased cement content improves the stability, which in turn enhances the wet strength to dry strength ratio [17,18]. In the sand–clay matrix, there is the possibility that the smaller clay particles ﬁll the voids of sand particles, resulting in an increase in density and decrease in void spaces as mentioned by Sekhar et al. (2018) [11]. Furthermore, in a study concerning the usage of crushed brick waste to produce CSEB presented by Kasinikota and Tripura (2021) [19], the CSH gel also ﬁlls up the void, making the structure impermeable and thereby increasing the rigidity of matrix [20,21]. The disposal of municipal solid waste (MSW) is a major environmental concern worldwide [22]. In 2012, around 1.3 billion tons of MSW were generated, which is estimated to become 2.2 billion tons by 2025 [23]. Incineration is often regarded as the most efﬁcient method for recycling MSW because of its great volume reduction capability and the ability to recover energy [24]. Most of this refuse is discarded in landﬁlls without any kind of retrieval or re-use, resulting in signiﬁcant economic and environmental issues. The quantity of ash that is produced from MSW following the incineration process accounts for approximately 25% of the total weight of MSW. Landﬁll space is limited in countries with a high population density [25]. Recent developments show that solid waste materials may be turned into a valuable resource in a circular economy to improve resource efﬁciency. As the MSWIBA contains Ca, Si and Al, it may be a suitable candidate as a raw material for cement production [26]. Improved energy efﬁciency, compressive strength and thermal comfort may be achieved by using MSWIBA as an alternative building material. The production process of Compressed Stabilized Earth Blocks (CSEBs) requires a signiﬁcant amount of ﬁne aggregates [27]. Using municipal solid waste incinerator bottom ash (MSWIBA) as a raw material in CSEB production could be a viable option for recycling MSWIBA and conserving clay, making it an environmentally friendly option for constructing earthen houses [11,28]. This study explores the potential of using MSWIBA as a partial replacement for ﬁne aggregates in CSEBs and inv estigates its effects on the mechanical and durability properties of these blocks. The various tests were conducted on samples containing varying percentages of cement and MSWIBA, and the results were compared to those of conventional earth blocks. This research aims to contribute to the development of sustainable building materials that promote environmental responsibility and waste reduction. The tests conducted follow ASTM standards and Indian Standards Institution norms, including wet and dry compressive strength, ﬂexural strength, water absorption, stress–strain behavior, and wetting and drying cycles [19]. The study provides Buildings 2023, 13, 1114 3 of 17 an in-depth account of the use of MSWIBA and cement in producing CSEBs as an eco- friendly construction material commonly used in earthen construction. 2. Materials and Methods 2.1. Soil Soil (containing a signiﬁcant amount of clay) collected from a depth between 2 to 5 m below ground level in Auroville, Pondicherry (India), was selected as the raw ma- terial. The collected soil sample was air dried, crushed to remove clods and then sieved through a 4.75 mm mesh screen. According to the conventional procedures enumerated by SP-36 (Part1) 1987 [29], the physical characteristics including liquid limit, plastic limit, shrinkage limit, particle size distribution, speciﬁc gravity and free swell were determined Table 1 [9,19,30,31]. According to the Indian Soil Classiﬁcation System, this soil can be clas- siﬁed as CH. For the manufacture of CEBs, AS HB 195 [32] and IS 1725 [33] recommended a sand proportion somewhere between 30% to 75% and 50% to 80%, which is more suitable for production of CEB. The sand mixture of 70% was selected to fabricate the CEB and an optimal soil–sand mixture 30:70 was determined according to [19]. Table 1. Characteristics of soil. Property Parameter Soil Liquid limit, LL 61.45% Atterberg limit Plastic limit, PL 35.67% Plasticity Index, PI 25.78% Sand 51.78% Slit 25.55% Grain size Distribution Clay 22.67% Optimum moisture content (OMC) 19.67% Proctor Test Maximum dry density (MDD) 1820 kg/m Shrinkage Limit 18.23% IS Soil Classiﬁcation CH 2.2. Cement Ordinary Portland Cement (OPC) Type I was used to produce CSEB. The chemical com- position is shown in Table 2 [31]. Evaluation of the physical characteristics demonstrated that the speciﬁc gravity was 3.15, initial and ultimate setting times were, respectively, 145 and 309 min, the 28-day compressive strength was 49.1 MPa and its ﬁneness was 326 m /kg Table 2. Table 2. Chemical composition of municipal solid waste incinerator bottom ash and OPC. Chemical Composition (%) Compound MSWIBA OPC (Type I) SiO 64.75 22.40 Al O 0.78 5.13 2 3 Fe O 0.38 3.98 2 3 CaO 14.85 61.64 MgO 0.74 1.26 K O - 0.61 Na O - 0.09 2 Buildings 2023, 13, 1114 4 of 17 Table 2. Cont. Chemical Composition (%) Compound MSWIBA OPC (Type I) SO - 1.14 C 15.53 - LOI - 3.75 2.3. Municipal Solid Waste Incinerator Bottom Ash (MSWIBA) The MSWIBA was collected from an incinerator plant located at Manali, North Chennai (India), where the MSWI bottom ash is produced at a rate of 2000 kg per day. The air- dried and pulverized MSWIBA, passing through a 4.75 mm sieve, was used to produce CSEBs [34]. The chemical composition of MSWIBA particles is shown in Table 2. The MSWIBA particles with a speciﬁc gravity of 2.30 were classiﬁed as Class F bottom ash. 2.4. Soil–Admixture Proportions This study examined the impact of various soil and admixture combinations on the strength and durability of compressed earth blocks. MSWIBA was used to replace ﬁne aggregates (sand) at a rate of 0% to 25%, depending on the mix. Based on the literature [26], blocks were prepared with varying cement contents (0%, 6%, 7%, 8%, 9%, and 10%). In evaluating the strength of the compressed stabilized earth blocks (CSEBs), a standard period of 28 days was adopted for all the casting blocks, irrespective of their mix ratios. This time period is widely accepted as it allows sufﬁcient time for the stabilizer material to cure and hydrate, thereby achieving the desired strength and durability of the CSEBs. By adopting this testing period, this study was able to obtain valuable information about the engineering properties of the CSEBs, including their strength and durability, which are critical factors for evaluating the quality of the blocks and identifying their potential uses. Table 3 contains detailed information regarding the type of test performed, as well as the quantity of blocks utilized in each test for each mix ratio. Table 3. Combination of cement and MSWIBA considered in this study. Cement MSWIBA No of Samples Testing 0% 5 Dry compression strength 6% 5 Wet compression strength 7% 0%, 5%, 10%, 15%, 5 Flexural strength 8% 20%, 25% 5 Water absorption 9% 3 Stress–strain behavior 10% 5 Wetting–drying test 2.5. Optimum Moisture Content (OMC) The CSEB preparation test was administered in a proctored environment, but with some adjustments. According to the deﬁnition, the optimum moisture content (OMC) is the point at which the dry density of the mixture may be maximized for a given level of compaction. When determining the OMC, the same methods used by [7,27,35,36] were applied. Both stabilized and un-stabilized soils were tested for no more than 45 min following the addition of water. A technique for measuring the hardness of a mixed dry mix is presented by [27]. CSEBs produced with 10% cement show the dry-density OMC. An OMC of 12–16% and a maximum dry density of 1812–2154 kg/m were observed for all the samples. The drop ball test, recommended by [27], was also carried out to assess the accuracy of water addition. Buildings 2023, 13, x FOR PEER REVIEW 5 of 17 sieved through a 1 mm mesh. In addition, the sand and MSWIBA were sieved through a 4.75 mm sieve. According to the calculations, the extent of air-dried materials, including soil, sand, MSWIBA and cement, were measured and combined [30]. According to the testing methodology, the soil was then mixed with the required Buildings 2023, 13, 1114 5 of 17 quantity of cement–MSWIBA. For the fabrication of CSEBs, 0–10% of cement and six pro- portions of MSWIBA (0%, 5%, 10%, 15%, 20% and 25%) were employed. Over-integrating MSWIBA by more than 25% would have led to block failure because of the soil’s low clay 2.6. Optimum Fabrication of Compressed Stabilized Earth Block concentration. The prepared wet mixture was scooped into the press mold, and any over- The dimensions of the blocks made using a block manufacturing machine were 240 mm age was afterwards removed. After the mixture was compacted using static compaction, 115 mm 90 mm in size. Figure 1 illustrates that the process of preparing blocks includes the block was gently removed from the compactor and placed on a level surface to cure multiple stages, such as batching, mixing, placing the mix, compacting, and ejection of the [37]. Blocks that had been pushed out of the mold were measured for weight and cured blocks. The lumps of dried soil were manually crushed with a rammer and then sieved for 28 days in a moistened tow sack. When the block was ejected, the weight and date of through a 1 mm mesh. In addition, the sand and MSWIBA were sieved through a 4.75 mm preparation were recorded, and an appropriate identiﬁcation number (for the series used) sieve. According to the calculations, the extent of air-dried materials, including soil, sand, was assigned for future reference. MSWIBA and cement, were measured and combined [30]. Figure 1. Figure 1. Flow Flowchart chart of produ of production ction of CSEB. of CSEB. According to the testing methodology, the soil was then mixed with the required quan- 2.7. Test Methods tity of cement–MSWIBA. For the fabrication of CSEBs, 0–10% of cement and six proportions The compressive strength of the stabilized earth blocks was measured using a 100- of MSWIBA (0%, 5%, 10%, 15%, 20% and 25%) were employed. Over-integrating MSWIBA ton compression testing equipment as per IS 3495 (Part 1): 1992 [38]. The combination of by more than 25% would have led to block failure because of the soil’s low clay concentra- wet and dry compressive strength was measured since wet strength may be advantageous tion. The prepared wet mixture was scooped into the press mold, and any overage was in the worst-case scenario. According to IS: 5454-1978 [39], a total of ﬁve samples were afterwards removed. After the mixture was compacted using static compaction, the block tested for each variation. The average value of the ﬁve samples was then used to represent was gently removed from the compactor and placed on a level surface to cure [37]. Blocks the compressive strength of all the mixtures tested. Figure 2a,b shows a test set up for that had been pushed out of the mold were measured for weight and cured for 28 days in a compressive strength and observed sample failure. The minimum acceptable compressive moistened tow sack. When the block was ejected, the weight and date of preparation were strength for the stabilized earth block is 3.5 MPa, according to IS: 1725-2013 [33]. The spec- recorded, and an appropriate identiﬁcation number (for the series used) was assigned for imen was prepared before subjecting it to the compression testing machine. The uneven- future reference. ness in the bed faces removed by grinding, resulting in two smooth and parallel surfaces. Cement mortar was used to ﬁll up the frog and any other holes in the bed. Then it was 2.7. Test Methods placed under moist jute bags for one day before being immersed in water for 3 days to The compressive strength of the stabilized earth blocks was measured using a 100-ton complete the process. To determine the wet compressive strength, the blocks were soaked compression testing equipment as per IS 3495 (Part 1): 1992 [38]. The combination of wet for 48 h in clean water, then were surface cleaned and tested using a universal testing and dry compressive strength was measured since wet strength may be advantageous machine [40]. in the worst-case scenario. According to IS: 5454-1978 [39], a total of ﬁve samples were The ﬂexural tensile strength in terms of modulus of rupture was determined by sub- tested for each variation. The average value of the ﬁve samples was then used to represent jecting specimens to a three-point bending ﬂexural test, as speciﬁed in Indonesian Stand- the compressive strength of all the mixtures tested. Figure 2a,b shows a test set up for compressive strength and observed sample failure. The minimum acceptable compressive strength for the stabilized earth block is 3.5 MPa, according to IS: 1725-2013 [33]. The specimen was prepared before subjecting it to the compression testing machine. The unevenness in the bed faces removed by grinding, resulting in two smooth and parallel surfaces. Cement mortar was used to ﬁll up the frog and any other holes in the bed. Then it was placed under moist jute bags for one day before being immersed in water for 3 days to complete the process. To determine the wet compressive strength, the blocks were soaked Buildings 2023, 13, x FOR PEER REVIEW 6 of 17 Buildings 2023, 13, 1114 6 of 17 ard SNI 03-6458-2000 [19], similar to the speciﬁcations in ASTM C67-02c [41]. The speci- men was loaded until failure, at a constant rate of 2.5 kN/min for 240 mm in a span using a universal testing equipment with a capacity of 200 kN. Figure 3a,b shows the arrange- for 48 h in clean water, then were surface cleaned and tested using a universal testing ment of the samples for ﬂexural strength test. machine [40]. Buildings 2023, 13, x FOR PEER REVIEW 6 of 17 ard SNI 03-6458-2000 [19], similar to the speciﬁcations in ASTM C67-02c [41]. The speci- men was loaded until failure, at a constant rate of 2.5 kN/min for 240 mm in a span using a universal testing equipment with a capacity of 200 kN. Figure 3a,b shows the arrange- ment of the samples for ﬂexural strength test. (a) (b) Figure 2. (a) Test set up for compressive strength and (b) observed crack patt ern of the sample. Figure 2. (a) Test set up for compressive strength and (b) observed crack pattern of the sample. The ﬂexural tensile strength in terms of modulus of rupture was determined by subjecting specimens to a three-point bending ﬂexural test, as speciﬁed in Indonesian Standard SNI 03-6458-2000 [19], similar to the speciﬁcations in ASTM C67-02c [41]. The specimen was loaded until failure, at a constant rate of 2.5 kN/min for 240 mm in a span (a) (b) using a universal testing equipment with a capacity of 200 kN. Figure 3a,b shows the Figure 2. (a) Test set up for compressive strength and (b) observed crack patt ern of the sample. arrangement of the samples for ﬂexural strength test. (a) (a) (b) Figure 3. (a) and (b) Flexural test setup for CSEB. The water absorption (WA) test according to IS 3495 (Part 1): 1992 [38] was performed on ﬁve samples (for each variation), as per IS: 5454 1978 [39]. con The initial weight was measured after the specimen was cooled to room temperature (M1). The specimen was then immersed in potable water for 24 h. The ﬁnal weight was taken after surface drying (b) Figure 3. (a) and (b) Flexural test setup for CSEB. Figure 3. (a,b) Flexural test setup for CSEB. The water absorption (WA) test according to IS 3495 (Part 1): 1992 [38] was performed on ﬁve samples (for each variation), as per IS: 5454 1978 [39]. con The initial weight was measured after the specimen was cooled to room temperature (M1). The specimen was then immersed in potable water for 24 h. The ﬁnal weight was taken after surface drying Buildings 2023, 13, 1114 7 of 17 Buildings 2023, 13, x FOR PEER REVIEW 7 of 17 The water absorption (WA) test according to IS 3495 (Part 1): 1992 [38] was performed Buildings 2023, 13, x FOR PEER REVIEW 7 of 17 on ﬁve samples (for each variation), as per IS: 5454 1978 [39]. con The initial weight was measured after the specimen was cooled to room temperature (M1). The specimen was for three minutes. Figure 4 shows the water immersion, surface drying of block and ﬁnal then immersed in potable water for 24 h. The ﬁnal weight was taken after surface drying for three minutes. Figure 4 shows the water immersion, surface drying of block and ﬁnal weight for the waste absorption test. The specimen was weighed 3 min after it was taken for three minutes. Figure 4 shows the water immersion, surface drying of block and ﬁnal weight for the waste absorption test. The specimen was weighed 3 min after it was taken out of water (M2), as shown in Figure 4. According to IS: 1725-2013 [33], the average water weight for the waste absorption test. The specimen was weighed 3 min after it was taken out of water (M2), as shown in Figure 4. According to IS: 1725-2013 [33], the average water absorption should not exceed 15% of the weight of the material. out of water (M2), as shown in Figure 4. According to IS: 1725-2013 [33], the average water absorption should not exceed 15% of the weight of the material. absorption should not exceed 15% of the weight of the material. Figure 4. Flowchart of water absorption test. Figure 4. Flowchart of water absorption test. Figure 4. Flowchart of water absorption test. The alternate wett ing and drying tests were carried out in accordance with IS: 1725- The alternate wetting and drying tests were carried out in accordance with IS: 1725- The alternate wett ing and drying tests were carried out in accordance with IS: 1725- 2013 [33], which is comparable to that mentioned in ASTM D559-03 [42]. Three specimens 2013 [33], which is comparable to that mentioned in ASTM D559-03 [42]. Three specimens 2013 [33], which is comparable to that mentioned in ASTM D559-03 [42]. Three specimens from each series were dried in a ventilated oven at 60 °C until their weight was constant. from each series were dried in a ventilated oven at 60 C until their weight was constant. from each series were dried in a ventilated oven at 60 °C until their weight was constant. The air-cooled blocks were immersed in water at room temperature for 5 h, and then dried The air-cooled blocks were immersed in water at room temperature for 5 h, and then dried The air-cooled blocks were immersed in water at room temperature for 5 h, and then dried in an oven at 70 °C for an additional 42 h. The dried blocks were scraped on all six sides in an oven at 70 C for an additional 42 h. The dried blocks were scraped on all six sides in an oven at 70 °C for an additional 42 h. The dried blocks were scraped on all six sides twice using a wire scratch brush, using a force of 1.5 kg for each stroke The method used twice using a wire scratch brush, using a force of 1.5 kg for each stroke The method used to twice using a wire scratch brush, using a force of 1.5 kg for each stroke The method used to scrape the dried blocks involved using a wire scratch brush to scrape with a force of 1.5 scrape the dried blocks involved using a wire scratch brush to scrape with a force of 1.5 kg to scrape the dried blocks involved using a wire scratch brush to scrape with a force of 1.5 kg for each stroke. To ensure the accuracy of the pressure applied by the brush stroke, we for each stroke. To ensure the accuracy of the pressure applied by the brush stroke, we kg for each stroke. To ensure the accuracy of the pressure applied by the brush stroke, we clamped the wider face of the specimen on one corner of a platform scale and set the scale clamped the wider face of the specimen on one corner of a platform scale and set the scale clamped the wider face of the specimen on one corner of a platform scale and set the scale to zero and then placed a standard weight of 1.5 kg on the brush to measure the pressure to zero and then placed a standard weight of 1.5 kg on the brush to measure the pressure as to zero and then placed a standard weight of 1.5 kg on the brush to measure the pressure as shown in Figure 5. The blocks were subjected to twelve similar cycles. The samples shown in Figure 5. The blocks were subjected to twelve similar cycles. The samples were as shown in Figure 5. The blocks were subjected to twelve similar cycles. The samples were then oven-dried and their ﬁnal weights were recorded. After 12 rounds of wett ing then oven-dried and their ﬁnal weights were recorded. After 12 rounds of wetting and were then oven-dried and their ﬁnal weights were recorded. After 12 rounds of wett ing and drying, the blocks were evaluated for their dry compressive strength and ﬂexural drying, the blocks were evaluated for their dry compressive strength and ﬂexural strength and drying, the blocks were evaluated for their dry compressive strength and ﬂexural strength to determine the performance. to determine the performance. strength to determine the performance. Figure 5. Measurement of pressure applied by wire scratch brush on the specimen. Figure 5. Measurement of pressure applied by wire scratch brush on the specimen. Figure 5. Measurement of pressure applied by wire scratch brush on the specimen. The weight of the block is measured immediately after demolding to determine how The weight of the block is measured immediately after demolding to determine how The weight of the block is measured immediately after demolding to determine how much moisture is present in the block. As the block dries, it loses moisture and its weight much moisture is present in the block. As the block dries, it loses moisture and its weight much moisture is present in the block. As the block dries, it loses moisture and its weight reduces. After the block was demolded, it was placed in a curing chamber or covered with reduces. After the block was demolded, it was placed in a curing chamber or covered with reduces. After the block was demolded, it was placed in a curing chamber or covered with a moist cloth to prevent the moisture from escaping too quickly. Curing is the process of a moist cloth to prevent the moisture from escaping too quickly. Curing is the process of a moist cloth to prevent the moisture from escaping too quickly. Curing is the process of keeping the block moist so that it can continue to gain strength and harden. The block is keeping the block moist so that it can continue to gain strength and harden. The block is keeping the block moist so that it can continue to gain strength and harden. The block is typically cured for 28 days, after which it reaches its maximum strength. Therefore, Figure 6 typically cured for 28 days, after which it reaches its maximum strength. Therefore, Figure typically cured for 28 days, after which it reaches its maximum strength. Therefore, Figure shows that the weight of the block was measured after demolding and after 28 days of 6 shows that the weight of the block was measured after demolding and after 28 days of 6 shows that the weight of the block was measured after demolding and after 28 days of curing to determine how much weight loss had occurred during the curing process. The curing to determine how much weight loss had occurred during the curing process. The curing to determine how much weight loss had occurred during the curing process. The weight loss is an indication of the moisture loss and the strength gain of the block. weight loss is an indication of the moisture loss and the strength gain of the block. weight loss is an indication of the moisture loss and the strength gain of the block. Buildings 2023, 13, x FOR PEER REVIEW 8 of 17 Buildings 2023, 13, 1114 8 of 17 (a) (b) (c) (d) (e) (f) Figure 6. Weight of block with various % of cement content (a) 0% cement, (b) 6% cement, (c) 7% Figure 6. Weight of block with various % of cement content (a) 0% cement, (b) 6% cement, (c) 7% ce- cement, (d) 8% cement, (e) 9% cement, (f) 10% cement. ment, (d) 8% cement, (e) 9% cement, (f) 10% cement. Buildings 2023, 13, x FOR PEER REVIEW 9 of 17 3. Results and Discussion 3.1. Mechanical Properties of Compressed Stabilized Earth Block 3.1.1. Dry and Wet Compressive Strength of Compressed Stabilized Earth Blocks The compressive strengths of CSEBs with and without MSWIBA were compared (dry and wet values taken after 28 days of curing, presented in Figure 7a,b). The dry and wet compressive strengths for the conventional earth blocks were, respectively, 3.50 and 1.68 MPa. In line with results from the literature, it was noted that the introduction of MSWIBA leads to a signiﬁcant enhancement in compressive strength when compared to the con- ventional earth block. The highest compressive strength was observed in the samples con- taining 10% cement, whereas the lowest compressive strength was noted in samples with- Buildings 2023, 13, 1114 9 of 17 out cement. Compressive strength improves with the cement content because of the stronger inter-particle connections from the cement hydration with the formation of cal- cium silicate hydrate (CSH) gels [43], binding the soil particles and ﬁlling the pores within 3. Results and Discussion the soil matrix. In addition, calcium aluminate silicate was formed when calcium hydrox- 3.1. Mechanical Properties of Compressed Stabilized Earth Block ide, a by-product of the crystallization of cement, reacts with the added MSWIBA [44]. In 3.1.1. Dry and Wet Compressive Strength of Compressed Stabilized Earth Blocks the CSEBs without cement content, the incorporation of MSWIBA does not have the same The compressive strengths of CSEBs with and without MSWIBA were compared (dry impact, and the strength of the system was not signiﬁcantly improved. An appropriate and wet values taken after 28 days of curing, presented in Figure 7a,b). The dry and quantity of MSWIBA must be added to the mixture in order to react with the hydrated wet compressive strengths for the conventional earth blocks were, respectively, 3.50 and product of cement crystallization. If the quantity of MSWIBA exceeds the required 1.68 MPa. In line with results from the literature, it was noted that the introduction of amount, the unreacted MSWIBA particles remain in the mixture, preventing the creation MSWIBA leads to a signiﬁcant enhancement in compressive strength when compared to the of strong interconnecting bonds with soil, thereby reducing the strength of the blocks. conventional earth block. The highest compressive strength was observed in the samples From the results, it was observed that the dry compressive strength values varied containing 10% cement, whereas the lowest compressive strength was noted in samples from 3.5 to 7.43 MPa and wet compressive strengths varied from 1.68 to 5.56 MPa, corre- without cement. Compressive strength improves with the cement content because of the sponding to 0–25% MSWIBA concentrations. The pozzolanic action and superior particle stronger inter-particle connections from the cement hydration with the formation of calcium size distribution of MSWIBA may be att ributed to this increase as reported by [45] and silicate hydrate (CSH) gels [43], binding the soil particles and ﬁlling the pores within the [44]. According to the standards, the wet strength should be over and above 0.7 MPa. The soil matrix. In addition, calcium aluminate silicate was formed when calcium hydroxide, dry compressive strength of the mixture containing 10% cement, and 15, 20 and 25% of a by-product of the crystallization of cement, reacts with the added MSWIBA [44]. In the MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while the wet compressive strengths CSEBs without cement content, the incorporation of MSWIBA does not have the same were, respectively, 4.10, 5.56 and 3.87 MPa. Superior strength was noted in the mixtures impact, and the strength of the system was not signiﬁcantly improved. An appropriate incorporating 10% cement and 20% MSWIBA. Figure 8 shows the wet-to-dry strength ra- quantity of MSWIBA must be added to the mixture in order to react with the hydrated tios for diﬀerent cement–MSWIBA combinations. It can be noted that the addition of an product of cement crystallization. If the quantity of MSWIBA exceeds the required amount, optimal quantity of MSWIBA to cement increases the wet-to-dry strength ratio, proving the unreacted MSWIBA particles remain in the mixture, preventing the creation of strong the need for stabilization. interconnecting bonds with soil, thereby reducing the strength of the blocks. (a) (b) Figure 7. (a) Dry compression strength and (b) wet compression strength varies with MSWIBA con- Figure 7. (a) Dry compression strength and (b) wet compression strength varies with MSWIBA centration. concentration. From the results, it was observed that the dry compressive strength values varied from 3.5 to 7.43 MPa and wet compressive strengths varied from 1.68 to 5.56 MPa, corre- sponding to 0–25% MSWIBA concentrations. The pozzolanic action and superior particle size distribution of MSWIBA may be attributed to this increase as reported by [44,45]. According to the standards, the wet strength should be over and above 0.7 MPa. The dry compressive strength of the mixture containing 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while the wet compressive strengths were, respectively, 4.10, 5.56 and 3.87 MPa. Superior strength was noted in the mixtures incorporating 10% cement and 20% MSWIBA. Figure 8 shows the wet-to-dry strength ratios for different cement–MSWIBA combinations. It can be noted that the addition of an optimal quantity of MSWIBA to cement increases the wet-to-dry strength ratio, proving the need for stabilization. Buildings 2023, 13, x FOR PEER REVIEW 10 of 17 Buildings 2023, 13, 1114 10 of 17 Figure 8. Wet-to-dry strength ratio. Figure 8. Wet-to-dry strength ratio. 3.1.2. Flexural Strength of Compressed Stabilized Earth Block 3.1.2. Flexural Strength of Compressed Stabilized Earth Block Figure 3 depicts the experimental setup for the ﬂexural test of CSEB and the results are Figure 3 depicts the experimental setup for the ﬂexural test of CSEB and the results shown in Figure 9. The conventional earth block exhibited a ﬂexural strength of 0.48 MPa. are shown in Figure 9. The conventional earth block exhibited a ﬂexural strength of 0.48 A progressive improvement in the ﬂexural strength may be noted with an increase in MPa. A progressive improvement in the ﬂexural strength may be noted with an increase the MSWIBA and cement content. The formation of cement hydration products and the Buildings 2023, 13, x FOR PEER REVIEW 11 of 17 in the MSWIBA and cement content. The formation of cement hydration products and the reaction with the MSWIBA help to improve the hydration cycle. Consequently, a greater reaction with the MSWIBA help to improve the hydration cycle. Consequently, a greater degree of bending resistance is provided by the soil matrix, which got tightly interconnected. degree of bending resistance is provided by the soil matrix, which got tightly intercon- The New Mexico [46] earthen building materials code recommends a minimum ﬂexural nected. The New Mexico [46] earthen building materials code recommends a minimum and 15, 20 and 25% of MSWIBA were, respectively, 12.4, 11.6 and 10.4%. The water ab- strength (in saturation) as 0.35 MPa, whereas the New Zealand Standard [47] and the Sri ﬂexural strength (in saturation) as 0.35 MPa, whereas the New Zealand Standard [47]and sorption of the specimen containing 7% cement was also comparable. These values were Lankan Standard [48] require stabilized earth bricks to have a ﬂexural strength above 0.25 the Sri Lankan Standard [48] require stabilized earth bricks to have a ﬂexural strength 12.8, 12.4 and 12.1%, respectively, at the MSWIBA content of 15, 20, and 25%. and 0.5 MPa, respectively [9]. above 0.25 and 0.5 MPa, respectively [9]. From the results, the ﬂexural strength of blocks comprising MSWIBA was higher than that of the conventional earth block. On average, the blocks had a ﬂexural strength of 26% to 28% of their compressive strength. The ﬂexural strengths of the mixture incor- porating 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 1.21, 1.32 and 0.83 MPa, as shown in Figure 9. Increasing MSWIBA from 10% to 20% increases the ﬂex- ural strength, on account of the pozzolanic activity and more uniform particle size distri- bution. The shape and roughness of MSWIBA, in addition to its pozzolanic action, are important factors in the development of strength. MSWIBA also acted as a connecting link between the cement–soil matrix, improving the performance. 3.1.3. Water Absorption of Compressed Stabilized Earth Block The stabilized earth blocks become less porous with age. After 28 days of curing, there was a notable reduction in water absorption across the board for all the blocks in- corporating 7–10% of cement. The chemical reaction of the cement with the alumino sili- cates in the soil generates cementitious products that bind soil particles together and so- lidify over time, minimizing void interconnectivity [14]. The water absorption of the con- ventional earth block was 14.4%. All the blocks exhibit water absorption varying between 10.2% to 14.4% at the end of the 28-day ageing period. With extended ageing, the water absorption values reduce considerably, as most of the specimens exhibited a water ab- Figure 9. Eﬀect of MSWIBA on the ﬂexural strength. Figure 9. Effect of MSWIBA on the ﬂexural strength. sorption far below the 15% maximum limit indicated by IS: 1725-2013 [33]. As shown in Figure 10, the water absorption of blocks improves with the increase in the quantity of From the results, the ﬂexural strength of blocks comprising MSWIBA was higher than cement and the MSWIBA. The water absorption of the mixture containing 10% cement, that of the conventional earth block. On average, the blocks had a ﬂexural strength of 26% Figure 10. Eﬀect of MSWIBA on the water absorption. 3.2. Alternate Wett ing–Drying The dry compressive strength of the mixture (at normal curing) containing 10% ce- ment and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while strengths were, respectively, 7.54, 7.98 and 6.43 MPa after the wett ing and drying cycles. A slight reduction in the compressive strength and ﬂexural strength was noted for the conventional earth block, following the wett ing–drying test, while an improvement in the strength may be noted for the specimen containing cement and MSWIBA. The gain in strength for the blocks containing 0% to 25% MSWIBA was in the range of 12–27% which Buildings 2023, 13, x FOR PEER REVIEW 11 of 17 Buildings 2023, 13, 1114 11 of 17 and 15, 20 and 25% of MSWIBA were, respectively, 12.4, 11.6 and 10.4%. The water ab- sorption of the specimen containing 7% cement was also comparable. These values were to 28% of their compressive strength. The ﬂexural strengths of the mixture incorporating 12.8, 12.4 and 12.1%, respectively, at the MSWIBA content of 15, 20, and 25%. 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 1.21, 1.32 and 0.83 MPa, as shown in Figure 9. Increasing MSWIBA from 10% to 20% increases the ﬂexural strength, on account of the pozzolanic activity and more uniform particle size distribution. The shape and roughness of MSWIBA, in addition to its pozzolanic action, are important factors in the development of strength. MSWIBA also acted as a connecting link between the cement–soil matrix, improving the performance. 3.1.3. Water Absorption of Compressed Stabilized Earth Block The stabilized earth blocks become less porous with age. After 28 days of curing, there was a notable reduction in water absorption across the board for all the blocks incorporating 7–10% of cement. The chemical reaction of the cement with the alumino silicates in the soil generates cementitious products that bind soil particles together and solidify over time, minimizing void interconnectivity [14]. The water absorption of the conventional earth block was 14.4%. All the blocks exhibit water absorption varying between 10.2% to 14.4% at the end of the 28-day ageing period. With extended ageing, the water absorption values reduce considerably, as most of the specimens exhibited a water absorption far below the 15% maximum limit indicated by IS: 1725-2013 [33]. As shown in Figure 10, the water absorption of blocks improves with the increase in the quantity of cement and the MSWIBA. The water absorption of the mixture containing 10% cement, and 15, 20 and 25% of MSWIBA were, respectively, 12.4, 11.6 and 10.4%. The water absorption of the specimen containing 7% cement was also comparable. These values were 12.8, 12.4 and Figure 9. Eﬀect of MSWIBA on the ﬂexural strength. 12.1%, respectively, at the MSWIBA content of 15, 20, and 25%. Figure 10. Eﬀect of MSWIBA on the water absorption. Figure 10. Effect of MSWIBA on the water absorption. 3.2. Alternate Wetting–Drying 3.2. Alternate Wett ing–Drying The dry compressive strength of the mixture (at normal curing) containing 10% cement The dry compressive strength of the mixture (at normal curing) containing 10% ce- and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while strengths ment and 15, 20 and 25% of MSWIBA were, respectively, 6.10, 7.43 and 5.98 MPa, while were, respectively, 7.54, 7.98 and 6.43 MPa after the wetting and drying cycles. A slight strengths were, respectively, 7.54, 7.98 and 6.43 MPa after the wett ing and drying cycles. reduction in the compressive strength and ﬂexural strength was noted for the conventional A slight reduction in the compressive strength and ﬂexural strength was noted for the earth block, following the wetting–drying test, while an improvement in the strength may conventional earth block, following the wett ing–drying test, while an improvement in the be noted for the specimen containing cement and MSWIBA. The gain in strength for the strength may be noted for the specimen containing cement and MSWIBA. The gain in blocks containing 0% to 25% MSWIBA was in the range of 12–27% which is mentioned in strength for the blocks containing 0% to 25% MSWIBA was in the range of 12–27% which Figure 11. Supplementary calcium silicate hydrate (CSH) gel was formed during the faster Buildings 2023, 13, x FOR PEER REVIEW 12 of 17 Buildings 2023, 13, x FOR PEER REVIEW 12 of 17 Buildings 2023, 13, 1114 12 of 17 is mentioned in Figure 11. Supplementary calcium silicate hydrate (CSH) gel was formed is mentioned in Figure 11. Supplementary calcium silicate hydrate (CSH) gel was formed during the faster hydration of the cement due to the pozzolanic reaction with MSWIBA at during the faster hydration of the cement due to the pozzolanic reaction with MSWIBA at 70 °C, which further enhanced the stiﬀness of the matrix [49]. Figure 12 shows the im- hydration of the cement due to the pozzolanic reaction with MSWIBA at 70 C, which 70 °C, which further enhanced the stiﬀness of the matrix [49]. Figure 12 shows the im- provement in ﬂexural strength of blocks after a series of wett ing–drying cycles. There was further enhanced the stiffness of the matrix [49]. Figure 12 shows the improvement in provement in ﬂexural strength of blocks after a series of wett ing–drying cycles. There was a notable improvement in the ﬂexural strength for the samples incorporating 10% cement ﬂexural strength of blocks after a series of wetting–drying cycles. There was a notable a notable improvement in the ﬂexural strength for the samples incorporating 10% cement and 10–25% MSWIBA. improvement in the ﬂexural strength for the samples incorporating 10% cement and and 10–25% MSWIBA. 10–25% MSWIBA. Figure 11. Dry compression strength of CSEB after alternate wett ing and drying. Figure 11. Dry compression strength of CSEB after alternate wetting and drying. Figure 11. Dry compression strength of CSEB after alternate wett ing and drying. Figure 12. Flexural strength of CSEB after alternate wett ing and drying. Figure 12. Flexural strength of CSEB after alternate wetting and drying. Figure 12. Flexural strength of CSEB after alternate wett ing and drying. 3.3. Stress–Strain Behavior of CSEB 3.3. Stress–Strain Behavior of CSEB 3.3. Stress–Strain Behavior of CSEB Dry and wet stress–strain behavior of CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, and 10% of cement, exhibited superior strength and durability. More straining was seen at lower stresses in the beginning for all CSEB samples. As strain Buildings 2023, 13, x FOR PEER REVIEW 13 of 17 Dry and wet stress–strain behavior of CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, and 10% of cement, exhibited superior strength and durability. More straining was seen at lower stresses in the beginning for all CSEB samples. As strain increases past the peak, the stress drops, and the CSEB specimens eventually fail. The strain values observed for the CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, and 10% of cement in the wet condition ranged between 0.02% and 0.18%. In contrast, for the dry state, the strain values were found to be higher, ranging between 0.24% and 1.10%. All the specimens showed a reduction in peak strain with time, with cement content and failure strain varying between 2.5% and 3.4%. An increase in cementi- Buildings 2023, 13, 1114 13 of 17 tious material–soil connections may lead to a stiﬀ axial response and a steep slope of axial stress–axial strain response. In Figure 13, peak stress and failure strain are greater for dry than wet samples. Stress–strain graphs are used to determine the initial tangent modulus increases past the peak, the stress drops, and the CSEB specimens eventually fail. The strain (ITM). The addition of various proportions of cement and MSWIBA resulted in a 40–50% values observed for the CSEB specimens containing 20% and 25% MSWIBA, and 8%, 9%, rise in ITM, with a maximum value of 2.89 GPa. and 10% of cement in the wet condition ranged between 0.02% and 0.18%. In contrast, for In both the dry and wet phases, it is important to notice that the elastic modulus the dry state, the strain values were found to be higher, ranging between 0.24% and 1.10%. increased signiﬁcantly with an increase in cement percentage from 8% to 9%. Upon add- All the specimens showed a reduction in peak strain with time, with cement content and ing 8–10% of cement, the elastic modulus in the wet blocks increased between 19% and failure strain varying between 2.5% and 3.4%. An increase in cementitious material–soil 42% compared to 15% and 20% for dry CSEB specimens. Similar reactions were obtained connections may lead to a stiff axial response and a steep slope of axial stress–axial strain for 15% and 20% MSWIBA, emphasizing the necessity to utilize 9% cement rather than response. In Figure 13, peak stress and failure strain are greater for dry than wet samples. 10% cement when producing CSEB using MSWIBA. Overall structural ductility may be Stress–strain graphs are used to determine the initial tangent modulus (ITM). The addition assured by using cement-stabilized blocks with strong mortar joints between them and by of various proportions of cement and MSWIBA resulted in a 40–50% rise in ITM, with a increasing the integration between the block and the mortar. maximum value of 2.89 GPa. Buildings 2023, 13, x FOR PEER REVIEW 14 of 17 (a) (b) Figure 13. Stress–strain response of CSEB sample (a) 20% MSWIBA and (b) 25% MSWIBA. Figure 13. Stress–strain response of CSEB sample (a) 20% MSWIBA and (b) 25% MSWIBA. 3.4. Microstructural Analysis The scanning electron microscopy (SEM) images given on Figure 14 conﬁrm the per- formance of cement and MSWIBA materials. SEM was conducted on polished and gold- coated brick chips samples at a magniﬁcation of 5000×. Micrographs were captured using backscatt ered electrons and were viewed. An increase in the compressive strength of blocks with MSWIBA was observed on account of the bett er ﬁlling when compared to the conventional earth block. The internal phase of the compressed stabilized earth block con- taining 10% cement with 20% MSWIBA exhibits a higher density and fewer voids in com- parison to the compressed stabilized earth block containing 10% cement with 15% and 25% MSWIBA, as depicted in Figure 14. The C-S-H gel formation in transition zone ap- pears to be superior in the specimen incorporating 10% of cement with 20% of MSWIBA, and it had a maximum compressive strength of 7.43 MPa. (a) (b) (c) Figure 14. SEM analysis, (a) 10% of cement with 15% of MSWIBA, (b) 10% of cement with 25% of MSWIBA, (c) 10% of cement with 20% of MSWIBA. 3.5. Cost Analysis The cost to construct a typical room, measuring 6 m× 3 m× 3 m, is calculated. In the design, a wall thickness of 0.3 m is considered, with three windows measuring 1.2 m × 1.2 m, and one door with dimension 1.2 m × 2.1 m. Figure 15 illustrates the structure as seen from the plan view perspective. The CSEB blocks have dimensions of 240 mm × 115 mm Buildings 2023, 13, x FOR PEER REVIEW 14 of 17 Buildings 2023, 13, 1114 14 of 17 In both the dry and wet phases, it is important to notice that the elastic modulus increased signiﬁcantly with an increase in cement percentage from 8% to 9%. Upon adding 8–10% of cement, the elastic modulus in the wet blocks increased between 19% and 42% compared to 15% and 20% for dry CSEB specimens. Similar reactions were obtained for 15% and 20% MSWIBA, emphasizing the necessity to utilize 9% cement rather than 10% cement when producing CSEB using MSWIBA. (b) Overall structural ductility may be assured by using cement-stabilized blocks with strong mortar joints between them and by increasing Figure 13. Stress–strain response of CSEB sample (a) 20% MSWIBA and (b) 25% MSWIBA. the integration between the block and the mortar. 3.4. Microstructural Analysis 3.4. Microstructural Analysis The scanning electron microscopy (SEM) images given on Figure 14 conﬁrm the per- The scanning electron microscopy (SEM) images given on Figure 14 conﬁrm the formance of cement and MSWIBA materials. SEM was conducted on polished and gold- performance of cement and MSWIBA materials. SEM was conducted on polished and coated brick chips samples at a magniﬁcation of 5000×. Micrographs were captured using gold-coated brick chips samples at a magniﬁcation of 5000. Micrographs were captured backscatt ered electrons and were viewed. An increase in the compressive strength of using backscattered electrons and were viewed. An increase in the compressive strength blocks with MSWIBA was observed on account of the bett er ﬁlling when compared to the of blocks with MSWIBA was observed on account of the better ﬁlling when compared to conventional earth block. The internal phase of the compressed stabilized earth block con- the conventional earth block. The internal phase of the compressed stabilized earth block taining 10% cement with 20% MSWIBA exhibits a higher density and fewer voids in com- containing 10% cement with 20% MSWIBA exhibits a higher density and fewer voids in parison to the compressed stabilized earth block containing 10% cement with 15% and comparison to the compressed stabilized earth block containing 10% cement with 15% and 25% MSWIBA, as depicted in Figure 14. The C-S-H gel formation in transition zone ap- 25% MSWIBA, as depicted in Figure 14. The C-S-H gel formation in transition zone appears pears to be superior in the specimen incorporating 10% of cement with 20% of MSWIBA, to be superior in the specimen incorporating 10% of cement with 20% of MSWIBA, and it and it had a maximum compressive strength of 7.43 MPa. had a maximum compressive strength of 7.43 MPa. (a) (b) (c) Figure 14. SEM analysis, (a) 10% of cement with 15% of MSWIBA, (b) 10% of cement with 25% of Figure 14. SEM analysis, (a) 10% of cement with 15% of MSWIBA, (b) 10% of cement with 25% of MSWIBA, (c) 10% of cement with 20% of MSWIBA. MSWIBA, (c) 10% of cement with 20% of MSWIBA. 3.5. Cost Analysis 3.5. Cost Analysis The cost to construct a typical room, measuring 6 m× 3 m× 3 m, is calculated. In the The cost to construct a typical room, measuring 6 m 3 m 3 m, is calculated. desi In the gn, a design, wall th aickness o wall thickness f 0.3 m is con of 0.3sm idered, w is conside ith t rh ed, ree window with three s m windows easuring 1 measuring .2 m × 1.2 m 1.2 , and on m 1.2 e dm, oor wit and h one dim door ension with 1.2dimension m × 2.1 m. Fi 1.2 gur me 152.1 illum. straFigur tes the e st 15ruct illustrates ure as seen the from the plan structure as seen view perspe from thectiv plan e. The CSEB view perspective. blocks hav The e dimensio CSEB blocks ns of have 240 m dimensions m × 115 mm of 240 mm 115 mm 90 mm (MSWIBA–cement) and 240 mm 120 mm 90 mm (sand– cement), and an approximate unit weight of 1850 kg/m . To manufacture 3900 earthen blocks, the estimated quantity of cement is 1300 kg and MSWIBA is 2900 kg. The Indian standard rates were utilized for all the costs of materials in this investigation, and the projected cost is estimated as USD 750. Modern construction practices employ CSEBs in the form of interlocking blocks, which signiﬁcantly minimizes the need for mortar and the associated cost. In addition, due to the added transportation expenses, the total cost of the CSEB was signiﬁcantly greater than the typical concrete block. For building an identical room using ﬁred clay bricks (FCBs), the total cost may be computed as USD 809 [27], while the overall construction cost for sand–cement-stabilized CSEBs is projected to be USD 862 [27]. The cost comparison reveals that utilizing CSEBs stabilized with MSWIBA might reduce the total construction costs by 8% compared to the price of FCBs and by 13% when compared to the price of CSEBs stabilized with cement and sand. MSWIBA and cement-stabilized CSEBs are therefore a cost-efﬁcient option. Buildings 2023, 13, x FOR PEER REVIEW 15 of 17 × 90 mm (MSWIBA–cement) and 240 mm × 120 mm × 90 mm (sand–cement), and an ap- proximate unit weight of 1850 kg/m . To manufacture 3900 earthen blocks, the estimated quantity of cement is 1300 kg and MSWIBA is 2900 kg. The Indian standard rates were utilized for all the costs of materials in this investigation, and the projected cost is esti- mated as USD 750. Modern construction practices employ CSEBs in the form of interlock- ing blocks, which signiﬁcantly minimizes the need for mortar and the associated cost. In addition, due to the added transportation expenses, the total cost of the CSEB was signif- icantly greater than the typical concrete block. For building an identical room using ﬁred clay bricks (FCBs), the total cost may be computed as USD 809 [27], while the overall con- struction cost for sand–cement-stabilized CSEBs is projected to be USD 862 [27]. The cost comparison reveals that utilizing CSEBs stabilized with MSWIBA might reduce the total construction costs by 8% compared to the price of FCBs and by 13% when compared to Buildings 2023, 13, 1114 15 of 17 the price of CSEBs stabilized with cement and sand. MSWIBA and cement-stabilized CSEBs are therefore a cost-eﬃcient option. (a) (b) Figure 15. Cost analysis. (a) Plan and (b) perspective view. Figure 15. Cost analysis. (a) Plan and (b) perspective view. 4. Conclusions 4. Conclusions This study evaluated the application of municipal solid waste incinerator bottom This study evaluated the application of municipal solid waste incinerator bott om ash ash (MSWIBA) to partially replace ﬁne aggregate and ordinary Portland cement (OPC) as (MSWIBA) to partially replace ﬁne aggregate and ordinary Portland cement (OPC) as sta- stabilizers in compressed earth blocks (CEBs). The amount of cement binder added to the bilizers in compressed earth blocks (CEBs). The amount of cement binder added to the mix varied from 0% to 10%. Additionally, a portion of the sand was replaced with MSWIBA mix varied from 0% to 10%. Additionally, a portion of the sand was replaced with in varying amounts ranging from 0% to 25%. This replacement of sand with MSWIBA MSWIBA in varying amounts ranging from 0% to 25%. This replacement of sand with resulted in a corresponding decrease in the sand content, which varied from 70% to 45% MSWIBA resulted in a corresponding decrease in the sand content, which varied from depending on the speciﬁc amount of MSWIBA added to the mix. An assessment was 70% to 45% depending on the speciﬁc amount of MSWIBA added to the mix. An assess- conducted to determine the strength and durability of compressed stabilized earth blocks ment was conducted to determine the strength and durability of compressed stabilized (CSEBs). This included evaluating the compressive strength in dry and wet conditions, earth blocks (CSEBs). This included evaluating the compressive strength in dry and wet ﬂexural strength, water absorption, and analyzing their behavior during alternate wetting conditions, ﬂexural strength, water absorption, and analyzing their behavior during alter- and drying, as well as their stress–strain behavior and microstructure. Based on the nate wett ing and drying, as well as their stress–strain behavior and microstructure. Based ﬁndings of this investigation, the addition of cement increases the mechanical and durability on the ﬁndings of this investigation, the addition of cement increases the mechanical and characteristics of the compressed earth blocks. The optimal quantity of MSWIBA was noted durability characteristics of the compressed earth blocks. The optimal quantity of as 15% for 6–7% cement and 20% for 10% cement content, while the optimal mix proportion MSWIBA was noted as 15% for 6–7% cement and 20% for 10% cement content, while the may vary depending on the type of cement and MSWIBA. If the cement and MSWIBA optimal mix proportion may vary depending on the type of cement and MSWIBA. If the content exceeds the optimal level, there could be a marginal reduction in strength and a rise cement and MSWIBA content exceeds the optimal level, there could be a marginal reduc- in water absorption. The cost of CSEBs stabilized with cement and MSWIBA was reduced by tion in strength and a rise in water absorption. The cost of CSEBs stabilized with cement 8–13% when compared with the earthen blocks stabilized with a cement–sand combination, and MSWIBA was reduced by 8–13% when compared with the earthen blocks stabilized demonstrating the economic advantage of cement–MSWIBA-stabilized CSEBs. with a cement–sand combination, demonstrating the economic advantage of cement– The utilization of bottom ash obtained from municipal solid waste incinerators in MSWIBA-stabilized CSEBs. the production of compressed stabilized earth blocks has the potential to maintain the The utilization of bott om ash obtained from municipal solid waste incinerators in the mechanical and durability properties of the blocks. Nevertheless, further research is production of compressed stabilized earth blocks has the potential to maintain the me- necessary to analyze the long-term performance, such as ageing tests, and ﬁeld studies chanical and durability properties of the blocks. Nevertheless, further research is neces- should be conducted to evaluate the performance of MSWIBA-stabilized CSEBs in different sary to analyze the long-term performance, such as ageing tests, and ﬁeld studies should climatic conditions and soil types. Author Contributions: Conceptualization, A.T.L. and B.M.; methodology, A.T.L. and B.M.; software, A.T.L., B.M. and B.S.T.; validation, A.T.L., B.M. and B.S.T.; formal analysis, A.T.L., B.M. and B.S.T.; investigation, A.T.L., B.M. and B.S.T.; resources, A.T.L., B.M. and B.S.T.; data curation, A.T.L., B.M. and B.S.T.; writing—original draft preparation, A.T.L., B.M. and B.S.T.; writing—review and editing, A.T.L., B.M. and B.S.T.; visualization, A.T.L., B.M. and B.S.T.; supervision, A.T.L. and B.M.; project administration, A.T.L., B.M. and B.S.T. All authors have read and agreed to the published version of the manuscript. Funding: This research did not receive any funding from any other sources. Data Availability Statement: This does not apply. Conﬂicts of Interest: The authors state that there is no conﬂict of interest in relation to the publication of this research. Buildings 2023, 13, 1114 16 of 17 References 1. Chauhan, P.; El Hajjar, A.; Prime, N.; Plé, O. Unsaturated behavior of rammed earth: Experimentation towards numerical modelling. Constr. Build. Mater. 2019, 227, 116646. [CrossRef] 2. Brito, M.R.; Marvila, M.T.; Linhares, J.A.T., Jr.; Azevedo, A.R.G.D. Evaluation of the Properties of Adobe Blocks with Clay and Manure. Buildings 2023, 13, 657. [CrossRef] 3. Lahdili, M.; El Abbassi, F.-E.; Sakami, S.; Aamouche, A. Mechanical and Thermal Behavior of Compressed Earth Bricks Reinforced with Lime and Coal Aggregates. Buildings 2022, 12, 1730. [CrossRef] 4. Binici, H.; Aksogan, O.; Shah, T. Investigation of ﬁbre reinforced mud brick as a building material. Constr. Build. Mater. 2005, 19, 313–318. [CrossRef] 5. Rovnaník, P.; Rovnaníková, P. Blended alkali-activated ﬂy ash/brick powder materials. Procedia Eng. 2016, 151, 108–113. [CrossRef] 6. Naganathan, S.; Yousef, A.; Mohamed, O.; Mustapha, K.N. Performance of bricks made using ﬂy ash and bottom ash. Constr. Build. Mater. 2015, 96, 576–580. [CrossRef] 7. Shariful, M.; Elahi, T.E.; Rafat, A.; Mumtaz, N. Effectiveness of ﬂy ash and cement for compressed stabilized earth block construction. Constr. Build. Mater. 2020, 255, 119392. 8. Elahi, T.E.; Rafat, A.; Shariful, M.; Mehzabin, F. Suitability of ﬂy ash and cement for fabrication of compressed stabilized earth blocks. Constr. Build. Mater. 2020, 263, 120935. [CrossRef] 9. Elahi, T.E.; Rafat, A.; Shariful, M. Engineering characteristics of compressed earth blocks stabilized with cement and ﬂy ash. Constr. Build. Mater. 2021, 277, 122367. [CrossRef] 10. Prashanth, R.; Selvan, S.S.; Balasubramanian, M. Experimental Investigation on Durability Properties of Concrete Added with Nano Silica. Rasayan J. Chem. 2019, 12, 685–690. [CrossRef] 11. Sekhar, D.C.; Nayak, S. Utilization of granulated blast furnace slag and cement in the manufacture of compressed stabilized earth blocks. Constr. Build. Mater. 2018, 166, 531–536. [CrossRef] 12. Nagaraj, H.; Shreyasvi, C. Compressed Stabilized Earth Blocks Using Iron Mine Spoil Waste—An Explorative Study. Procedia Eng. 2017, 180, 1203–1212. [CrossRef] 13. Contreras, M.; Teixeira, S.R.; Lucas, M.C.; Lima, L.C.N.; Cardoso, D.S.L.; da Silva, G.A.C.; Gregório, G.C.; de Souza, A.E.; dos Santos, A. Recycling of construction and demolition waste for producing new construction material (Brazil case-study). Constr. Build. Mater. 2016, 123, 594–600. [CrossRef] 14. Hb, N.; Kv, A.; Nc, D. Utilization of granite sludge in the preparation of durable compressed stabilized earth blocks. MOJ Civ. Eng. 2018, 4, 237–243. [CrossRef] 15. Choi, W.; Jeon, C. Development and performance veriﬁcation of quality improvement equipment for recycled ﬁne aggregate and soil. J. Mater. Cycles Waste Manag. 2021, 23, 1331–1347. [CrossRef] 16. Agamuthu, P.; Victor, D. Policy Evolution of Solid Waste Management in Malaysia. J. Mater. Cycles Waste Manag. 2009, 11, 916–924. 17. Ouedraogo, K.; Aubert, J.; Tribout, C.; Millogo, Y.; Escadeillas, G. Ovalbumin as natural organic binder for stabilizing unﬁred earth bricks: Understanding vernacular techniques to inspire modern constructions. J. Cult. Heritage 2021, 50, 139–149. [CrossRef] 18. Banerjee, R.; Goswami, P.; Mukherjee, A. Stabilization of iron ore mine spoil dump sites with vetiver system. In Bio-Geotechnologies for Mine Site Rehabilitation; Elsevier: Amsterdam, The Netherlands, 2018; pp. 393–413. 19. Kasinikota, P.; Tripura, D.D. Evaluation of compressed stabilized earth block properties using crushed brick waste. Constr. Build. Mater. 2021, 280, 122520. [CrossRef] 20. Turco, C.; Junior, A.C.P.; Teixeira, E.R.; Mateus, R. Optimisation of Compressed Earth Blocks (CEBs) using natural origin materials: A systematic literature review. Constr. Build. Mater. 2021, 309, 125140. [CrossRef] 21. Muntohar, A.S. Engineering characteristics of the compressed-stabilized earth brick. Constr. Build. Mater. 2011, 25, 4215–4220. [CrossRef] 22. Haiying, Z.; Youcai, Z.; Jingyu, Q. Utilization of municipal solid waste incineration (MSWI) ﬂy ash in ceramic brick: Product characterization and environmental toxicity. Waste Manag. 2011, 31, 331–341. [CrossRef] [PubMed] 23. Silva, R.V.; De Brito, J.; Lynn, C.J.; Dhir, R.K. Use of municipal solid waste incineration bottom ashes in alkali- activated materials, ceramics and granular applications: A review. Waste Manag. 2017, 68, 207–220. [CrossRef] 24. Chen, D.M. The world’ s growing municipal solid waste: Trends and impacts The world’ s growing municipal solid waste: Trends and impacts. Environ. Res. Lett. 2020, 15, 74021. [CrossRef] 25. Jesudass, A.; Gayathri, V.; Geethan, R.; Gobirajan, M.; Venkatesh, M. Earthen blocks with natural ﬁbres—A review. Mater. Today Proc. 2021, 45, 6979–6986. [CrossRef] 26. Rahla, K.M.; Mateus, R.; Bragança, L. Implementing Circular Economy Strategies in Buildings—From Theory to Practice. Appl. Syst. Innov. 2021, 4, 26. [CrossRef] 27. Islam, M.S.; Elahi, T.E.; Shahriar, A.R.; Nahar, K.; Hossain, T.R. Strength and Durability Characteristics of Cement-Sand Stabilized Earth Blocks. J. Mater. Civ. Eng. 2020, 32. [CrossRef] 28. Oti, J.; Kinuthia, J.; Bai, J. Engineering properties of unﬁred clay masonry bricks. Eng. Geol. 2009, 107, 130–139. [CrossRef] 29. SP-36 (Part1); Compendium of Indian Standards on Soil Engineering: Lab Testing of soils for Civil Engineering purposes. Bureau of Indian Standards: New Delhi, India, 1987. Buildings 2023, 13, 1114 17 of 17 30. Concrete, G.; Block, I.; Agricultural, F. Investigation of compressed earth brick containing ceramic waste investigation of compressed earth brick containing. ARPN J. Eng. Appl. Sci. 2016, 11, 5459–5462. 31. Nagaraj, H.; Rajesh, A.; Sravan, M. Inﬂuence of soil gradation, proportion and combination of admixtures on the properties and durability of CSEBs. Constr. Build. Mater. 2016, 110, 135–144. [CrossRef] 32. AS HB 195; The Australian Earth Building Handbook. Standard Australia: Sydney, Australia, 2002. 33. IS: 1725; Speciﬁcation for soil based blocks used in general building construction. Bureau of Indian Standards: New Delhi, India, 34. Teerajetgul, W.; Sinthaworn, S. Effects of Using Fine Quarry Waste as Cement Replacement Material on the Compressive Strength of the Mixture of Interlocking Block. Adv. Mater. Res. 2014, 1032, 2348–2353. [CrossRef] 35. Bahar, R.; Benazzoug, M.; Kenai, S. Performance of compacted cement-stabilised soil. Cem. Concr. Compos. 2004, 26, 811–820. [CrossRef] 36. Tripura, D.D.; Singh, K.D. Characteristic Properties of Cement-Stabilized Rammed Earth Blocks. J. Mater. Civ. Eng. 2015, 27, 1–8. [CrossRef] 37. Balkis, A.P. The effects of waste marble dust and polypropylene ﬁber contents on mechanical properties of gypsum stabilized earthen. Constr. Build. Mater. 2017, 134, 556–562. [CrossRef] 38. IS:3495-Part1; Methods of Tests of Burnt Clay Building Bricks. Bureau of Indian Standards: New Delhi, India, 1992. 39. IS 5454; Methods for Sampling of Clay Building Bricks. Bureau of Indian Standards: New Delhi, India, 1978. 40. Chou, M.-I.M.; Patel, V.; Laird, C.J.; Ho, K.K. Chemical and Engineering Properties of Fired Bricks Containing 50 Weight Percent of Class F Fly Ash. Energy Sources 2001, 23, 665–673. [CrossRef] 41. ASTM C 67-02c; Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile. Annual Book of ASTM Standards: Conshohocken, PA, USA, 2002. 42. ASTM D 559-03; Test Methods for Wetting and Drying Compacted Soil–Cement Mixtures. Annual Book of ASTM Standards: Conshohocken, PA, USA, 2003. 43. Gandia, R.M.; Gomes, F.C.; Aparecida, A.; Corrêa, R.; Rodrigues, M.C.; Mendes, R.F. Physical, mechanical and thermal behavior of adobe stabilized with glass ﬁber reinforced polymer waste. Constr. Build. Mater. 2019, 222, 168–182. [CrossRef] 44. Seco, A.; Omer, J.; Marcelino, S.; Espuelas, S.; Prieto, E. Sustainable unﬁred bricks manufacturing from construction and demolition wastes. Constr. Build. Mater. 2018, 167, 154–165. [CrossRef] 45. Oti, J.E.; Kinuthia, J.M.; Robinson, R.B. Applied Clay Science The development of un ﬁ red clay building material using Brick Dust Waste and Mercia mudstone clay. Appl. Clay Sci. 2014, 102, 148–154. [CrossRef] 46. New Mexico Earthen Building Materials Code; New Mexico Administrative: Santa Fe, NM, USA, 2011; pp. 1–28. 47. NZS 4298; Materials and Workmanship for Earth Buildings (Building Code Compliance Document E2). Standards New Zealand: Wellington, New Zealand, 1998; Volume 4298. 48. UN-Habitat Sri Lanka Sustainable Construction Using Alternative Technologies Compressed Stabilized Earth Blocks (CSEB) for Wall Construction. 2015. Available online: https://unhabitat.lk/wp-content/uploads/2016/04/Compressed-Stabilized-Earth- Blocks-CSEB-for-Wall-Construction.pdf (accessed on 3 April 2014). 49. Hallal, M.M.; Sadek, S.; Najjar, S.S. Evaluation of Engineering Characteristics of Stabilized Rammed-Earth Material Sourced from Natural Fines-Rich Soil. J. Mater. Civ. Eng. 2018, 30, 4018273. [CrossRef] Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

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Buildings – Multidisciplinary Digital Publishing Institute

Published: Apr 22, 2023

Keywords: municipal solid waste incinerator bottom ash; sustainable cementitious material; compressed stabilized earth blocks; microstructure

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Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

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Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

Compressed Stabilized Earth Block Incorporating Municipal Solid Waste Incinerator Bottom Ash as a Partial Replacement for Fine Aggregates

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