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Abstract
applied sciences Article Thermal and Mechanical Properties of Cement Mortar Composite Containing Recycled Expanded Glass Aggregate and Nano Titanium Dioxide 1 1 , 1 2 3 Ali Yousefi , Waiching Tang * , Mehrnoush Khavarian , Cheng Fang and Shanyong Wang School of Architecture and Built Environment, University of Newcastle, Callaghan, NSW 2308, Australia; ali.yousefi@newcastle.edu.au (A.Y.); mehrnoush.khavarian@newcastle.edu.au (M.K.) Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan, NSW 2308, Australia; cheng.fang@newcastle.edu.au School of Civil Engineering, University of Newcastle, Callaghan, NSW 2308, Australia; shanyong.wang@newcastle.edu.au * Correspondence: patrick.tang@newcastle.edu.au; Tel.: +61-249-217-246 Received: 14 February 2020; Accepted: 20 March 2020; Published: 26 March 2020 Abstract: One of the growing concerns in the construction industry is energy consumption and energy eciency in residential buildings. Moreover, management of non-degradable solid glass wastes is becoming a critical issue worldwide. Accordingly, incorporation of recycled expanded glass aggregates (EGA) as a substitution for natural fine aggregate in cement composites would be a sustainable solution in terms of energy consumption in the buildings and waste management. This experimental research aims to investigate the e ects of EGA on fresh and hardened properties and thermal insulating performance of cement mortar. To enhance the mechanical properties and water resistance of the EGA-mortar, nano titanium dioxide (nTiO ) was used as nanofillers. The results showed an increase in workability and water absorption of the EGA-mortar. In addition, a significant decrease in bulk density and compressive strength observed by incorporating EGA into the cement mortar. The EGA-mortar exhibited a low heat transfer rate and excellent thermal insulation property. Furthermore, inclusion of nTiO increased compressive strength and water resistance of EGA-mortar, however, their heat transfer rate was increased. The results demonstrated that EGA-mortar can be integrated into the building envelop or non-load bearing elements such as wall partition as a thermal resistance to reduce the energy consumption in residential buildings. Keywords: industrial waste; sustainable concrete; recycled expanded glass 1. Introduction In the last few decades, demand for energy consumption in the residential building has risen and there is a high intention for reducing energy consumption in the buildings. The energy eciency of the buildings has become increasingly critical with the rising costs of energy as well as increasing awareness on global warming e ects [1,2]. Furthermore, waste management has become a critical issue. In fact, non-degradable wastes such as glass are unable to break down naturally which is developing environmental problems [3]. In Australia, about 1.1 Mt of glass waste was generated in the year of 2016–2017 from that 43% was stockpiled. In New South Wales, companies accepting the landfill levy to dump their glass waste in landfill or arranging to relocate the waste to other states where the landfill levy does not apply. Thus, use of waste glass in the large scale is a sustainable solution in terms of reduction of carbon footprint and saving the costs and energy. The construction industry is a potential sector for utilization of waste glass. In this regard, use of solid wastes for manufacturing the building materials with high thermal insulation properties is an e ective approach toward sustainable Appl. Sci. 2020, 10, 2246; doi:10.3390/app10072246 www.mdpi.com/journal/applsci Appl. Sci. 2020, 10, 2246 2 of 14 development and decreasing the energy consumption in buildings [4–6]. It has been reported that the incorporation of insolation materials in the building can reduce the indoor temperature fluctuation up to 4 C that would save 10–30% of energy usage [1,2]. Although many investigations have been carried out on utilizing waste glass in the form of glass powder [7–11] and glass bead [12–15] in concrete products, it has not found its position in the construction industry yet. Expanded glass aggregates (EGA), is a new commercial product, which are manufactured from waste and post-consumer glass. The EGA possess a relatively smooth surface with numerous encapsulated pores can be used as an insulating material [16]. The porous structure and low thermal conductivity of EGA can e ectively reduce the heat transfer rate. The utilization of EGA in cementitious materials brings two-fold advantages, first, reducing the landfill cost and environment and secondly can reduce the energy consumption in buildings [16]. Recently, some studies [17–21] have been conducted to investigate the e ect of EGA on mechanical and thermal properties of concrete and cement mortar, however, the utilization of EGA as an insulating material is at the initial stage. The great advantage of EGA is the possibility of production in a variety of size. Such a variety of particle sizes allows the improvement of the homogeneity of mixture and consequently reduces the possibility of segregation of the mixture [22]. Yu et al. [23] and Spiesz et al. [24] developed a cement-based lightweight composite using five di erent size of EGA (range between 0.1 and 2.0 mm) and reported the density of 1280–1490 kg/m and compressive strength of 23.3–30.2 MPa. Rumsys et al. [21] prepared cement mortar with two types of fine expanded aggregates (expanded glass and expanded clay) to compare their compressive strength and durability properties. In the mixes, they replaced the fine aggregates with expanded glass and expanded clay by the weight of the sand (8.5, 16.7, 33.3, 66.7, and 100 wt%). The obtained results revealed that in the mixtures with 100% EGA, the density decreased about 37% and the compressive strength after 28 days of curing dropped about 60%. The results also confirmed that EGA could be applied in the cementitious composites without limitation related to the alkali-silica reaction. In the experiment conducted by Namsone et al. [25], a foamed matrix was prepared using EGA and the mechanical, thermal and frost resistance properties were examined. They obtained the compressive of 4.7 and 5.7 MPa at the age of 7 and 28 days and the thermal conductivity of 0.152–0.108 W/m.K. Moreover, it was observed that reference samples had lower values of weight loss (g/m ) after the freeze–thaw test comparing to compositions with EGA. They also characterized the microstructure of the prepared foam matrix using optical microscopy and observed that EGA were distributed uniformly over the cross-section without any processes of segregation. Abd Elrahman et al. [16] fabricated EGA-cement mortar and reported crushing resistance of 1.9–2.9 N/mm and water absorption of 13.6–15.8 wt% depending on the particle size. The results showed a compressive strength of about 6 MPa and thermal conductivity less than 0.14 W/m.K. In the study conducted by [26], the influence of the grain size and percentage of EGA content on physical and mechanical properties of the cement composite were investigated. They reported an average porosity of 45–67% and bulk density of 903–1078 kg/m in specimens containing 100% EGA with the size of 2–4 mm. Moreover, the compressive strengths of 6.68–12.49 MPa obtained for EGA cement mortar. In another attempt, [27] investigated the possibility of using artificial neural networks to design the composition of cement composite containing EGA with the desired properties. They established the relation between the quantity of EGA and the porosity, bulk density, and compressive strength of a cement composite. Moreover, previous studies revealed that high glass content (above 50%) could considerably increase the water absorption of cementitious composites [28,29]. It can be concluded that incorporation of EGA in cement mortar can significantly reduce the mechanical properties such as compressive strength and water resistance of cement matrix. Hence, in order to compensate the reduction in mechanical strength and water absorption of cementitious composites integrated with EGA, nanofillers such as TiO can be used. Previous researches have demonstrated that the addition of TiO nanoparticles e ectively enhanced the compressive strength and reduce the water absorption of cementitious composites [30–35]. Indeed, nTiO fills the nanovoids in concrete, which leads to the 2 Appl. Sci. 2020, 10, 2246 3 of 14 Appl. Sci. 2020, 10, x FOR PEER REVIEW 3 of 14 S-H gel by increasing the amount of crystalline Ca(OH)2 at the early age of hydration [32,37]. Ma et increment of compressive strength up to 40% [34,36]. Moreover, TiO accelerates the formation of al. [32] reported 37% and 44% increase in tensile and flexural strength respectively for the samples C-S-H gel by increasing the amount of crystalline Ca(OH) at the early age of hydration [32,37]. Ma containing TiO2. In addition, the results indicated that the addition of TiO2 could significantly refine et al. [32] reported 37% and 44% increase in tensile and flexural strength respectively for the samples the pores and shift them to the harmless pores. In the research conducted by Behfarnia et al. [31], it containing TiO . In addition, the results indicated that the addition of TiO could significantly refine 2 2 was observed that TiO2 nanoparticles decreased the permeability of the cement matrix. In the research the pores and shift them to the harmless pores. In the research conducted by Behfarnia et al. [31], conducted by Khushwaha et al. [34] and Sorathiya et al. [33], the effect of various proportion of TiO2 it was observed that TiO nanoparticles decreased the permeability of the cement matrix. In the was studied. It was concluded that addition of TiO2 up to 1% could significantly enhance the research conducted by Khushwaha et al. [34] and Sorathiya et al. [33], the e ect of various proportion mechanical properties of concrete. of TiO was studied. It was concluded that addition of TiO up to 1% could significantly enhance the 2 2 This research aims to develop a cement mortar with a lower heat transfer rate and insulating mechanical properties of concrete. properties using substitution of a natural aggregate (NA) with EGA. In this study, the effect of This research aims to develop a cement mortar with a lower heat transfer rate and insulating incorporation of EGA and TiO2 nanoparticles on workability, bulk density, water penetration, properties using substitution of a natural aggregate (NA) with EGA. In this study, the e ect of compressive strength, and heat transfer rate of the cement mortar were investigated. Infrared incorporation of EGA and TiO nanoparticles on workability, bulk density, water penetration, thermography (IRT) was used to measure the thermal insulation property of EGA cement mortar. compressive strength, and heat transfer rate of the cement mortar were investigated. Infrared The IRT technique has been utilized to evaluate the thermal energy storage performance of building thermography (IRT) was used to measure the thermal insulation property of EGA cement mortar. materials in previous studies [38], however it has not been used for measuring the thermal insulating The IRT technique has been utilized to evaluate the thermal energy storage performance of building property of the EGA cement mortar. The conducted research is an additional step toward materials in previous studies [38], however it has not been used for measuring the thermal insulating development of insulating building material and sustainable application of EGA in the construction property of the EGA cement mortar. The conducted research is an additional step toward development industry. of insulating building material and sustainable application of EGA in the construction industry. 2. 2. Ma Materials terials a and nd Me Methods thods 2.1. Materials 2.1. Materials The materials used in the study to fabricate cement mortar composite were ordinary Portland The materials used in the study to fabricate cement mortar composite were ordinary Portland cement (OPC), natural aggregate (NA), recycled expanded glass aggregate (EGA), superplasticizer cement (OPC), natural aggregate (NA), recycled expanded glass aggregate (EGA), superplasticizer (SP), and nano titanium dioxide (nTiO ). OPC from Boral Australia Co. and in accordance with AS3972 (SP), and nano titanium dioxide (nTiO2). OPC from Boral Australia Co. and in accordance with was used as a binder and Sikament NN was used as a superplasticizer (SP) in the mix, which meets all AS3972 was used as a binder and Sikament NN was used as a superplasticizer (SP) in the mix, which requirements as per AS1478.1 for high range water reducing admixture. EGA with a particle size of meets all requirements as per AS1478.1 for high range water reducing admixture. EGA with a particle 0.25-4 mm from EGT Co. is shown in Figure 1. The specifications of EGA are compliant with EN and size of 0.25-4 mm from EGT Co. is shown in Figure 1. The specifications of EGA are compliant with DIN standards. Figure 2 shows a SEM image of the utilized EGA in this study. Table 1 demonstrates EN and DIN standards. Figure 2 shows a SEM image of the utilized EGA in this study. Table 1 the physical, mechanical, and thermal properties of the EGA. demonstrates the physical, mechanical, and thermal properties of the EGA. 0.25–0.5 mm 0.5–1.0 mm 1.0–2.0 mm 2.0–4.0 mm Fig Figure ure 1 1. . E Expanded xpanded g glass lass a aggr ggreg egate ate ( (EGA) EGA) w with ith a a di di ffer erent ent grain grain size. size. Table 1. Physical, mechanical, and thermal properties of the EGA (Expanded Glass Technologies). Grain Size Property 0.25–0.5 0.5–1 1–2 2–4 Loose bulk density (kg/m ) 300 250 220 190 Particle density (kg/m ) 540 450 350 310 Compressive strength (MPa) 2.9 2.6 2.4 2.2 Thermal conductivity (W/mK) 0.07 0.07 0.07 0.07 Appl. Sci. 2020, 10, x FOR PEER REVIEW 3 of 14 S-H gel by increasing the amount of crystalline Ca(OH)2 at the early age of hydration [32,37]. Ma et al. [32] reported 37% and 44% increase in tensile and flexural strength respectively for the samples containing TiO2. In addition, the results indicated that the addition of TiO2 could significantly refine the pores and shift them to the harmless pores. In the research conducted by Behfarnia et al. [31], it was observed that TiO2 nanoparticles decreased the permeability of the cement matrix. In the research conducted by Khushwaha et al. [34] and Sorathiya et al. [33], the effect of various proportion of TiO2 was studied. It was concluded that addition of TiO2 up to 1% could significantly enhance the mechanical properties of concrete. This research aims to develop a cement mortar with a lower heat transfer rate and insulating properties using substitution of a natural aggregate (NA) with EGA. In this study, the effect of incorporation of EGA and TiO2 nanoparticles on workability, bulk density, water penetration, compressive strength, and heat transfer rate of the cement mortar were investigated. Infrared thermography (IRT) was used to measure the thermal insulation property of EGA cement mortar. The IRT technique has been utilized to evaluate the thermal energy storage performance of building materials in previous studies [38], however it has not been used for measuring the thermal insulating property of the EGA cement mortar. The conducted research is an additional step toward development of insulating building material and sustainable application of EGA in the construction industry. 2. Materials and Methods 2.1. Materials The materials used in the study to fabricate cement mortar composite were ordinary Portland cement (OPC), natural aggregate (NA), recycled expanded glass aggregate (EGA), superplasticizer (SP), and nano titanium dioxide (nTiO2). OPC from Boral Australia Co. and in accordance with AS3972 was used as a binder and Sikament NN was used as a superplasticizer (SP) in the mix, which meets all requirements as per AS1478.1 for high range water reducing admixture. EGA with a particle size of 0.25-4 mm from EGT Co. is shown in Figure 1. The specifications of EGA are compliant with EN and DIN standards. Figure 2 shows a SEM image of the utilized EGA in this study. Table 1 demonstrates the physical, mechanical, and thermal properties of the EGA. 0.25–0.5 mm 0.5–1.0 mm 1.0–2.0 mm 2.0–4.0 mm Appl. Sci. 2020, 10, 2246 4 of 14 Figure 1. Expanded glass aggregate (EGA) with a different grain size. Appl. Sci. 2020, 10, x FOR PEER REVIEW 4 of 14 Figure 2. SEM pictures of the utilized EGA. Table 1. Physical, mechanical, and thermal properties of the EGA (Expanded Glass Technologies). Grain Size Property 0.25-0.5 0.5–1 1–2 2–4 Loose bulk density (kg/m ) 300 250 220 190 Particle density (kg/m ) 540 450 350 310 Compressive strength (MPa) ≥2.9 ≥2.6 ≥2.4 ≥2.2 Thermal conductivity (W/mK) 0.07 0.07 0.07 0.07 Figure 2. SEM pictures of the utilized EGA. Crushed gravel with the maximum size of 4.0 mm and density of 2800 kg/m was used as NA. Crushed gravel with the maximum size of 4.0 mm and density of 2800 kg/m was used as NA. The NA was subjected to the particle size distribution test to precisely replicate the distribution of The NA was subjected to the particle size distribution test to precisely replicate the distribution of NA for the replacement of EGA by volume in the cement mortar. The size distribution testing was NA for the replacement of EGA by volume in the cement mortar. The size distribution testing was completed in accordance with AS1012 and the results are found in Figure 3. completed in accordance with AS1012 and the results are found in Figure 3. Figure 3. Size distribution of the natural aggregate and EGA. Figure 3. Size distribution of the natural aggregate and EGA. Moreover, the mercury intrusion porosimetry (MIP) test was undertaken to measure the porosity as well as pore size distribution of the EGA. The MIP test results of the EGA are revealed in Figure 4. Moreover, the mercury intrusion porosimetry (MIP) test was undertaken to measure the poroNanoparticles sity as well as po titanium re size ddioxide istributio (nT n oiO f th)e pur EGA chased . The M in IP te thestpowder results oform f the Efr G om A are US reResear vealedch in Nanomaterials, Inc. Table 2 demonstrates the properties of the nTiO as indicated by the manufacturer. Figure 4. Table 2. The properties of the nano-nTiO (US Research Nanomaterials, Inc.). Properties Value Purity 99.98% Average Particles Size 30 (nm) Specific surface area 50 (m /g) Bulk Density 0.42 (g/cm ) True Density 3.9 g/cm ) PH 5.5–6.5 Appl. Sci. 2020, 10, 2246 5 of 14 Appl. Sci. 2020, 10, x FOR PEER REVIEW 5 of 14 0.328m EGA (2-4 mm) EGA (1-2 mm) 0.481 m 0.01 0.1 1 10 100 Pore S ize Diameter (m) Figure 4. Pore size distribution of the EGA. Figure 4. Pore size distribution of the EGA. 2.2. Sample Preparation Nanoparticles titanium dioxide (nTiO2) purchased in the powder form from US Research The mixes had a water to cement ratio of 0.4 and a sand to cement ratio of 3:1. Two set of mixes Nanomaterials, Inc. Table 2 demonstrates the properties of the nTiO2 as indicated by the were prepared: the first set of mixes were fabricated by partial and full replacement of NA with EGA manufacturer. without inclusion of nTiO . The designed mixes with 0%, 50%, and 100% replacement percentage of Table 2. The properties of the nano-nTiO2 (US Research Nanomaterials, Inc.). EGA implied with CS, E50, and E100, respectively. The second set of mixes was fabricated by partial and full replacement of NA with EGA and incorporation of 1% nTiO . The designed mixes with Properties Value incorporation of TiO and the EGA replacement percentage of 0%, 50%, and 100% defined as CT, E50T, Purity 99.98% and E100T, respectively. Average Particles Size 30 (nm) To fabricate the mixes, the dry materials (cement and NA/EGA) were placed in the mixer and Specific surface area 50 (m /g) mixed on the low speed for 2.0 min. In the case of CT, E50T, and E100T mixes, the nTiO were sonicated 3 2 Bulk Density 0.42 (g/cm ) for 15 min in the solution of water and superplasticizer (SP) [39]. Then the dispersed nTiO /SP/water 3 2 True Density 3.9 g/cm ) solution was added slowly to the mix and the materials were mixed for another 5 min. The mixes PH 5.5–6.5 cast in 70 70 70 mm cubes and demolded after 24 h. The samples were cured in the fog room at a constant temperature of 23 C and in accordance with AS1012.8. Table 3 demonstrates the mix 2.2. Sample Preparation proportion of the samples. The abbreviations for labeling each mix are defined in a way that the letters The mixes had a water to cement ratio of 0.4 and a sand to cement ratio of 3:1. Two set of mixes C and E representing control sample and mortar sample containing EGA respectively and number were prepared: the first set of mixes were fabricated by partial and full replacement of NA with EGA after the letters presents the percentage of NA replacement with EGA into the mixture. The letter T without inclusion of nTiO2. The designed mixes with 0%, 50%, and 100% replacement percentage of demonstrates the presence of TiO in the mix. For instance, the E50T mixture represents the sample EGA implied with CS, E50, and E100, respectively. The second set of mixes was fabricated by partial that contains 50% EGA and TiO . and full replacement of NA with EGA and incorporation of 1% nTiO2. The designed mixes with incorporation of TiO2 and the EGA replacement percentage of 0%, 50%, and 100% defined as CT, Table 3. Mix proportion of the samples (kg/m ) of mortar. E50T, and E100T, respectively. Composite ID NA EGA Cement Water S.P nTiO To fabricate the mixes, the dry materials (cement and NA/EGA) were placed in the mixer and CS 1750 0 525 233 11.7 - mixed on the low speed for 2.0 min. In the case of CT, E50T, and E100T mixes, the nTiO2 were CT 1750 0 525 233 11.7 1% sonicated for 15 min in the solution of water and superplasticizer (SP) [39]. Then the dispersed E50 875 133 525 233 8.8 - nTiO2/SP/water solution was added slowly to the mix and the materials were mixed for another 5 E50T 875 133 525 233 8.8 1% min. The mixes cast in 70 × 70 × 70 mm cubes and demolded after 24 h. The samples were cured in E100 0 267 525 233 5.8 - E100T 0 267 525 233 5.8 1% the fog room at a constant temperature of 23 °C and in accordance with AS1012.8. Table 3 demonstrates the mix proportion of the samples. The abbreviations for labeling each mix are defined in a way that the letters C and E representing control sample and mortar sample containing EGA 2.3. Experimental Tests respectively and number after the letters presents the percentage of NA replacement with EGA into The flow table test was undertaken on the fresh cement mortar samples in accordance to the the mixture. The letter T demonstrates the presence of TiO2 in the mix. For instance, the E50T mixture AS2701 to measure the mixtures workability and consistency. Moreover, the density of the mixture represents the sample that contains 50% EGA and TiO 2. was determined via the density test according to AS2701. To measure the water penetration of the Log Differential Intrusion (ml/g) Appl. Sci. 2020, 10, x FOR PEER REVIEW 6 of 14 Table 3. Mix proportion of the samples (kg/m ) of mortar. Composite ID NA EGA Cement Water S.P nTiO2 CS 1750 0 525 233 11.7 - CT 1750 0 525 233 11.7 1% E50 875 133 525 233 8.8 - E50T 875 133 525 233 8.8 1% E100 0 267 525 233 5.8 - E100T 0 267 525 233 5.8 1% 2.3. Experimental Tests The flow table test was undertaken on the fresh cement mortar samples in accordance to the Appl. Sci. 2020, 10, 2246 6 of 14 AS2701 to measure the mixtures workability and consistency. Moreover, the density of the mixture was determined via the density test according to AS2701. To measure the water penetration of the specimens, the water absorption test was conducted in accordance with AS1012.21 at the age of 28 days. specimens, the water absorption test was conducted in accordance with AS1012.21 at the age of 28 The compressive test was undertaken on the cube specimens with the size of 70 mm 70 mm 70 mm days. The compressive test was undertaken on the cube specimens with the size of 70 mm × 70 mm × and in accordance with AS1012.9 at the age of 7, 14, and 28 days. For each test, three samples were 70 mm and in accordance with AS1012.9 at the age of 7, 14, and 28 days. For each test, three samples tested and the average including the error bar were reported. were tested and the average including the error bar were reported. In this study, the thermal insulation property and heat transfer rate of cement mortar containing In this study, the thermal insulation property and heat transfer rate of cement mortar containing EGA was evaluated by measuring the surface temperature distribution using infrared thermal imaging EGA was evaluated by measuring the surface temperature distribution using infrared thermal camera. imaging For camer this a. Fo purpose, r this pur the po specimens se, the spec with imens the wi dimension th the dimof ens 70 ion mm of 7 0 70 mm mm × 7 0 m 30 mmm × 30 wer mm e prepared and kept at about 27 C for a few hours to allow all samples to achieve the same initial were prepared and kept at about 27 °C for a few hours to allow all samples to achieve the same initial temperatur temperature e. . Then Then the th samples e sampl wer es e were exposed expo to sed a heat to sour a hea cet and sourc thee surface and th temperatu e surface r etempe distribution rature of the other side was captured by an infrared thermal camera for 15 min (Testo 872, Testo Australia). distribution of the other side was captured by an infrared thermal camera for 15 min (Testo 872, Testo The Aust thermal ralia). The test was therm repeated al test for was thr re ee pe times ated for for each three sample. times fFigur or eae ch 5 illustrates sample. Fi agure schematic 5 illust diagram rates a of sch the emthermal atic diagra test. m of the thermal test. Insulation Board (ClimaFoam® XPS ) S ample 120 mm 175 mm Heat source (275W HPM instant Thermal Camera heat lamp) 30 mm Figure 5. Infrared thermography test. Figure 5. Infrared thermography test. 3. Results and Discussion 3. Results and Discussion 3.1. Workability 3.1. Workability Figure 6 shows the flow table test and the flow table test results are presented in Table 4. The flow Figure 6 shows the flow table test and the flow table test results are presented in Table 4. The table test values were determined by averaging the diameters of each mixes test. All mixes showed flow table test values were determined by averaging the diameters of each mixes test. All mixes flow values in the range of 140–215 mm, without segregation or bleeding. The results revealed that showed flow values in the range of 140–215 mm, without segregation or bleeding. The results addition of EGA increased the workability of cement mortar up to 26.6% and 41.25% for the E50 and revealed that addition of EGA increased the workability of cement mortar up to 26.6% and 41.25% E100 mixes respectively compared to the control mix (CS). The increment trend in workability despite for the E50 and E100 mixes respectively compared to the control mix (CS). The increment trend in the decreasing on the amount of superplasticizer in E50 and E100 mixes is contributed to the smooth workability despite the decreasing on the amount of superplasticizer in E50 and E100 mixes is surface and spherical shape of EGA [40–42]. Adding to this, the increase in the flow values can be due contributed to the smooth surface and spherical shape of EGA [40–42]. Adding to this, the increase to the increase in the amount of entrapped air voids. Furthermore, the workability of CT, E50T, and E100T mixes increased by 5.35%, 30.4%, and 53.7% respectively in comparison to the CS, E50, and E100 mixes respectively, which is attributed to the induction of the microbubble in the water solution during the sonication process and consequently increased in small air voids in the mixes. Table 4. Flow results of mixes. Mix ID Average Flow Diameter (mm) CS 140.0 E50 177.3 E100 201.3 CT 147.5 E50T 182.5 E100T 215.3 Appl. Sci. 2020, 10, x FOR PEER REVIEW 7 of 14 in the flow values can be due to the increase in the amount of entrapped air voids. Furthermore, the workability of CT, E50T, and E100T mixes increased by 5.35%, 30.4%, and 53.7% respectively in comparison to the CS, E50, and E100 mixes respectively, which is attributed to the induction of the microbubble in the water solution during the sonication process and consequently increased in small Appl. Sci. 2020, 10, 2246 7 of 14 air voids in the mixes. Figure 6. Flow table test. Figure 6. Flow table test. 3.2. Density Table 4. Flow results of mixes. The density of the samples was measured, and the results are demonstrated in Figure 7. The Mix ID Average Flow Diameter (mm) measurement revealed the density of 2354, 1769, and 987 kg/m for C.S, E50, and E100 respectively. CS 140.0 It shows the density of E50 and E100 decreased 30% and 65% respectively in comparison to the CS, E50 177.3 which is attributed to the very low density of EGA and its porous structure. In addition, the densities E100 201.3 of CT, E50T, and E100T were 2%, 3%, and 6% higher than CS, E50, and E100 respectively. It can be CT 147.5 concluded that the increase in density was attributed to the lower porosity in the cement matrix due to E50T 182.5 the incorporation of nTiO . It is noteworthy that E100 with density of 987 kg/m was classified as a E100T 215.3 lightweight mortar that can be used for production of lightweight concrete. Figure 8 illustrates the cross section of CS and E100 samples. 3.A 2p . pD l. S ens ci. it 20y 20 , 10, x FOR PEER REVIEW 8 of 14 The density of the samples was measured, and the results are demonstrated in Figure 7. The measurement revealed the density of 2354, 1769, and 987 Kg/m for C.S, E50, and E100 respectively. It shows the density of E50 and E100 decreased 30% and 65% respectively in comparison to the CS, which is attributed to the very low density of EGA and its porous structure. In addition, the densities of CT, E50T, and E100T were 2%, 3%, and 6% higher than CS, E50, and E100 respectively. It can be concluded that the increase in density was attributed to the lower porosity in the cement matrix due to the incorporation of nTiO2. It is noteworthy that E100 with density of 987 kg/m was classified as a lightweight mortar that can be used for production of lightweight concrete. Figure 8 illustrates the cross section of CS and E100 samples. Figure 7. Density and water absorption of mix specimens. Figure 7. Density and water absorption of mix specimens. 3.3. Water Absorption The water absorption test was completed on all mixes and the results are shown in Figure 7. The water absorption of 4.19% obtained for control sample (CS) however a higher water absorption rate was obtained for the mixes containing EGA. The water absorption of E50 and E100 mixes were 7.47% and 14.74% respectively, which shows a 78% and 252% increase in the permeability of the matrix, compared to the control sample. The increase in water absorption is due to the high porosity of EGA in comparison to NA. The results revealed that the water penetration increased by increasing the EGA (a) (b) Figure 8. Cross-section of (a) the control sample (CS) and (b) E100 mixtures samples with uniform distribution of EGA in the cement matrix. 3.3. Water Absorption The water absorption test was completed on all mixes and the results are shown in Figure 7. The water absorption of 4.19% obtained for control sample (CS) however a higher water absorption rate was obtained for the mixes containing EGA. The water absorption of E50 and E100 mixes were 7.47% and 14.74% respectively, which shows a 78% and 252% increase in the permeability of the matrix, compared to the control sample. The increase in water absorption is due to the high porosity of EGA in comparison to NA. The results revealed that the water penetration increased by increasing the EGA content. The water absorption rate obtained for the E100 (values of approximately 14%) was higher than the acceptable range (<10%) [43,44]. The addition of nTiO2 reduced the water absorption value by 28%, 17%, and 2% for samples containing 0%, 50%, and 100% EGA respectively. The decrease in water absorption upon the inclusion of nTiO2 coincides with previous studies [45] and aligns with the density results. The reduction in water absorption was attributed to the filling effect of nTiO2 and reducing the porosity of the cement matrix. It is worthy to note that the sonication process resulted in tiny bubbles of air uniformly distributed in the mortar. These small bubbles are like entraining air that improves the workability of the mixes. Indeed, nTiO2 acted as nanofillers in mortar and improved the resistance to water penetration of the cement composite [46]. Appl. Sci. 2020, 10, x FOR PEER REVIEW 8 of 14 Appl. Sci. 2020, 10, 2246 8 of 14 content. The water absorption rate obtained for the E100 (values of approximately 14%) was higher than the acceptable range (<10%) [43,44]. The addition of nTiO reduced the water absorption value by 28%, 17%, and 2% for samples containing 0%, 50%, and 100% EGA respectively. The decrease in water absorption upon the inclusion of nTiO coincides with previous studies [45] and aligns with the density results. The reduction in water absorption was attributed to the filling e ect of nTiO and reducing the porosity of the cement matrix. It is worthy to note that the sonication process resulted in tiny bubbles of air uniformly distributed in the mortar. These small bubbles are like entraining air that improves the workability of the mixes. Indeed, nTiO acted as nanofillers in mortar and improved the resistance to water penetration of the cement composite [46]. Figure 7. Density and water absorption of mix specimens. (a) (b) Figure 8. Cross-section of (a) the control sample (CS) and (b) E100 mixtures samples with uniform Figure 8. Cross-section of (a) the control sample (CS) and (b) E100 mixtures samples with uniform distribution of EGA in the cement matrix. distribution of EGA in the cement matrix. 3.4. Compressive Strength 3.3. Water Absorption The experimental test for compressive strength was carried out at di erent curing ages of 7, 14, The water absorption test was completed on all mixes and the results are shown in Figure 7. The and 28 days. Figure 9 shows the impact of EGA and TiO inclusion on the compressive strength of water absorption of 4.19% obtained for control sample (CS) however a higher water absorption rate the mortar composites at di erent ages. It is observed that the inclusion of the EGA significantly was obtained for the mixes containing EGA. The water absorption of E50 and E100 mixes were 7.47% decreased the compressive strength of cement mortar. The results of 28-day compressive strength and 14.74% respectively, which shows a 78% and 252% increase in the permeability of the matrix, demonstrated that 50% replacement of NA with EGA reduced the strength about 65.8% in compare to compared to the control sample. The increase in water absorption is due to the high porosity of EGA the control sample (C.S). In addition, it was observed that as the EGA content increased from 50% to in comparison to NA. The results revealed that the water penetration increased by increasing the 100%, the compressive strength dropped dramatically from 26.25 to 8.20 MPa at the age of 28 days. EGA content. The water absorption rate obtained for the E100 (values of approximately 14%) was It is noteworthy that the compressive strength was still in the acceptable range and similar or higher higher than the acceptable range (<10%) [43,44]. The addition of nTiO2 reduced the water absorption than reported results in the literature [21,25]. Namsone et al. [25] reported the 28-day compressive of value by 28%, 17%, and 2% for samples containing 0%, 50%, and 100% EGA respectively. The 5.7 MPa for a foamed matrix using EGA and obtained the compressive strengths of 6.68-12.49 MPa for decrease in water absorption upon the inclusion of nTiO2 coincides with previous studies [45] and the EGA cement mortar. Indeed, the samples containing 100% EGA without nTiO had the lowest aligns with the density results. The reduction in water absorption was attributed to the filling effect compressive strength out of all the mixes. of nTiO2 and reducing the porosity of the cement matrix. It is worthy to note that the sonication Furthermore, the results indicated a normal increasing trend for the compressive strength for CS, process resulted in tiny bubbles of air uniformly distributed in the mortar. These small bubbles are E50, and E100 mixes as the curing process progresses. However, the mixes containing nTiO revealed a like entraining air that improves the workability of the mixes. Indeed, nTiO2 acted as nanofillers in relatively di erent strength development tend. It was revealed that CT, E50T, and E100T mixes reached mortar and improved the resistance to water penetration of the cement composite [46]. to 84.6%, 87.2%, and 77.2% of maximum strength within 7 days of curing while for samples without nTiO (CS, E50, and E100 mixes) it happened at 14 days of curing. This behavior was attributed to the addition of nTiO into the cementitious materials, which resulted in an accelerated rate of hydration process. A similar attribute has been reported in previous studies that when nTiO is uniformly distributed throughout the matrix, the hydration process and formation of C-S-H gel is accelerated, which results in early strength [32,47,48]. In the other set of mixes, the e ect of nTiO inclusion on the compressive strength of mixes was investigated after a di erent curing time. The compressive strength results of E50T and E100T mixes at 28 days showed the similar trend. It was observed that the addition of EGA significantly decreased the compressive strength and the strength significantly dropped as the EGA content increased however, inclusion of nTiO compensated some part of the compressive 2 Appl. Sci. 2020, 10, x FOR PEER REVIEW 9 of 14 3.4. Compressive Strength The experimental test for compressive strength was carried out at different curing ages of 7, 14, and 28 days. Figure 9 shows the impact of EGA and TiO2 inclusion on the compressive strength of the mortar composites at different ages. It is observed that the inclusion of the EGA significantly decreased the compressive strength of cement mortar. The results of 28-day compressive strength demonstrated that 50% replacement of NA with EGA reduced the strength about 65.8% in compare to the control sample (C.S). In addition, it was observed that as the EGA content increased from 50% Appl. Sci. 2020, 10, 2246 9 of 14 to 100%, the compressive strength dropped dramatically from 26.25 to 8.20 MPa at the age of 28 days. It is noteworthy that the compressive strength was still in the acceptable range and similar or higher than reported results in the literature [21,25]. Namsone et al. [25] reported the 28-day compressive of strength. The average compressive strength at 28 days of CT, E50T, and E100T mixes were 76.72, 29.70, 5.7 MPa for a foamed matrix using EGA and obtained the compressive strengths of 6.68-12.49 MPa and 11.4 MPa respectively, which shows 1.7%, 13.1%, and 39.0% enhancement in comparison to CS, for the EGA cement mortar. Indeed, the samples containing 100% EGA without nTiO2 had the lowest E50, and E100 mixes respectively. It can be concluded that nTiO acts as nanofillers in specimens and compressive strength out of all the mixes. recovers their pore structure by decreasing voids and pores in the composite matrix [46]. Figure 9. Compressive strength of samples at di erent ages. Figure 9. Compressive strength of samples at different ages. In summary it can be concluded that the compressive strength and water absorption of concrete are Furthermore, the results indicated a normal increasing trend for the compressive strength for highly influenced by the density of the mix. The results revealed an interrelationship between density CS, E50, and E100 mixes as the curing process progresses. However, the mixes containing nTiO 2 and compressive strength. It was observed that the compressive strength dropped by decrement of the revealed a relatively different strength development tend. It was revealed that CT, E50T, and E100T sample’s density (CS, E50, and E100 mixes). Similarly, an increase in density for CT, E50T, and E100T mixes reached to 84.6%, 87.2%, and 77.2% of maximum strength within 7 days of curing while for mixes resulted in an increase in compressive strength compared to CS, E50, and E100 mixes respectively. samples without nTiO2 (CS, E50, and E100 mixes) it happened at 14 days of curing. This behavior was Moreover, the results demonstrated an inverse relation between density and water absorption. It was attributed to the addition of nTiO2 into the cementitious materials, which resulted in an accelerated found that water absorption increased by decreasing the density of the mixes in case of CS, E50, and rate of hydration process. A similar attribute has been reported in previous studies that when nTiO2 E100. However, the water absorption decreased by integration of TiO2 into the mixes (CT, E50T, and is uniformly distributed throughout the matrix, the hydration process and formation of C-S-H gel is E100T) and increment of density due to a lower porosity of the matrix. accelerated, which results in early strength [32, 47–48]. In the other set of mixes, the effect of nTiO2 inclusion on the compressive strength of mixes was investigated after a different curing time. The 3.5. Infrared Thermography compressive strength results of E50T and E100T mixes at 28 days showed the similar trend. It was In order to evaluate the thermal insulating properties of the cement composites, the infrared observed that the addition of EGA significantly decreased the compressive strength and the strength sitgn heirfm ica on gtl ra y pd hro y ( ppe IRTd ) e ax s p th er e im EG en A t w coa n stent carriin ecr d ea oused t on ha olwev l theer sa , m inp cllusi es: o C nS o , f E n 50 Ti , O E1 2 0 co 0,m Cpe STn , s Ea 5ted 0T, so anm d e E 100T. pa Frt igu of r e th 1e 0co illm uspr tra essi tesv th e e sttre he n rgt mh a.l The imag ae vs er oa fge sur co fam ce pr te ess mp iv ee ra st tu re re ng dth ist r ait b2 u 8t id oa nyo s fotfh CT e sa , E m 5p 0lT es , a cn ad p tE u1 r0 e0 dT b y the mixes were 76.72, 29.70, and 11.4 MPa respectively, which shows 1.7%, 13.1%, and 39.0% IRT camera at different heating times. According to the relationship between the color and temperature value, it can be suggested that the heat-transferring rate and thermal conductivity of cement composites were significantly decreased with the inclusion of EGA. The thermal images clearly demonstrate a different temperature distribution in the control sample (CS mix) and the samples containing EGA (E50 and E100 mixes). The results show that the temperature increased rapidly in the CS however, a noticeable slower heat transfer rate observed for samples incorporated with EGA (E50 and E100). The data also revealed a drop in the heat transfer rate as the EGA content increased. For instance, after 15 min the average surface temperature in the CS sample reached 55 C while the average surface temperature in the E50 and E100 samples reached 52.7 and 48.7 C respectively, which shows a temperature difference of 2.3 C and 6.0 C for E50 and E100 respectively. Moreover, the results demonstrated the heat transfer rate of 1.75, 1.60, and 1.35 C/min for CS, E50, and E100 respectively that shows a lower rate for samples Appl. Sci. 2020, 10, x FOR PEER REVIEW 10 of 14 enhancement in comparison to CS, E50, and E100 mixes respectively. It can be concluded that nTiO2 acts as nanofillers in specimens and recovers their pore structure by decreasing voids and pores in the composite matrix [46]. In summary it can be concluded that the compressive strength and water absorption of concrete are highly influenced by the density of the mix. The results revealed an interrelationship between density and compressive strength. It was observed that the compressive strength dropped by decrement of the sample’s density (CS, E50, and E100 mixes). Similarly, an increase in density for CT, E50T, and E100T mixes resulted in an increase in compressive strength compared to CS, E50, and E100 mixes respectively. Moreover, the results demonstrated an inverse relation between density and water absorption. It was found that water absorption increased by decreasing the density of the mixes in case of CS, E50, and E100. However, the water absorption decreased by integration of TiO2 into the mixes (CT, E50T, and E100T) and increment of density due to a lower porosity of the matrix. 3.5. Infrared Thermography In order to evaluate the thermal insulating properties of the cement composites, the infrared thermography (IRT) experiment was carried out on all the samples: CS, E50, E100, CST, E50T , and E100T. Figure 10 illustrates the thermal images of surface temperature distribution of the samples captured by the IRT camera at different heating times. According to the relationship between the color and temperature value, it can be suggested that the heat-transferring rate and thermal conductivity of cement composites were significantly decreased with the inclusion of EGA. The thermal images clearly demonstrate a different temperature distribution in the control sample (CS mix) and the samples containing EGA (E50 and E100 mixes). The results show that the temperature increased rapidly in the CS however, a noticeable slower heat transfer rate observed for samples incorporated with EGA (E50 and E100). The data also revealed a drop in the heat transfer rate as the EGA content increased. For instance, after 15 min the average surface temperature in the CS sample reached 55 °C while the average surface temperature in the E50 and E100 samples reached 52.7 and Appl. Sci. 2020, 10, 2246 10 of 14 48.7 °C respectively, which shows a temperature difference of 2.3 °C and 6.0 °C for E50 and E100 respectively. Moreover, the results demonstrated the heat transfer rate of 1.75, 1.60, and 1.35 °C/min for CS, E50, and E100 respectively that shows a lower rate for samples containing EGA (E50 and E100) containing EGA (E50 and E100) in comparison to the control sample (CS). This observation was attributed in comparison to the control sample (CS). This observation was attributed to a high porosity and low to a high porosity and low thermal conductivity of EGA. Indeed, by incorporation of EGA the air void is thermal conductivity of EGA. Indeed, by incorporation of EGA the air void is replaced with sand, replaced with sand, which has a high thermal conductivity. EGA has a thermal conductivity of 0.07 W/mK which has a high thermal conductivity. EGA has a thermal conductivity of 0.07 W/mK that is much that is much less than that of sand (Expanded Glass Technologies). Consequently, by replacing the NA less than that of sand (Expanded Glass Technologies). Consequently, by replacing the NA with EGA with th EG e A heta h t tr e h ae na sfe t tr ra on f s th fee r ce ofm th ent c e ceo m m epo ntsi co te m wa po ss re ite duce was dr . e duced. Time Mix 0 min 5 min 7 min 10 min 11 min 13 min 15 min 70 C CS 60 C 55 C 50 C Max: 29.1°C Max: 34.9 °C Max: 40.1 °C Max: 47.4 °C Max: 49.9 °C Max: 54.0 °C Max: 55.0 °C Min: 28.0 °C Min: 30.6 °C Min: 33.3 °C Min: 44.6 °C Min: 43.1 °C Min: 46.7 °C Min: 50.0 °C 45 C Avg: 28.7 °C Avg: 33.1 °C Avg: 37.6 °C Avg: 41.0 °C Avg: 46.9 °C Avg: 51.1 °C Avg: 55.0 °C 40 C 35 C 30 C CT 25 C 5 C Max: 29.1°C Max: 33.8 °C Max: 39.1 °C Max: 47.2 °C Max: 49.6 °C Max: 54.6 °C Max: 58.9 °C Min: 28.3 °C Min: 31.8 °C Min: 35.7 °C Min: 42.3 °C Min: 44.2 °C Min: 48.5 °C Min: 51.9 °C Appl. Sci Avg . 2020 : 2, 810 .7 , °C x FOR Avg PEE : 3 R2 R .8E °C VI EWAvg : 37.5 °C Avg: 45.1 °C Avg: 47.4 °C Avg: 52.4 °C Avg: 56.8 °C11 of 14 70 C E50 60 C 55 C 50 C Max: 29.4 °C Max: 32.9 °C Max: 37.5 °C Max: 44.6 °C Max: 46.7 °C Max: 50.8 °C Max: 54.9 °C Min: 27.9 °C Min: 29.2 °C Min: 31.1 °C Min: 34.3 °C Min: 35.5 °C Min: 37.6 °C Min: 39.8 °C 45 C Avg: 28.7 °C Avg: 32.1 °C Avg: 36.1 °C Avg: 42.7 °C Avg: 44.6 °C Avg: 48.6 °C Avg: 52.7 °C 40 C 35 C 30 C E50T 25 C 5 C Max: 29.5 °C Max: 35.5 °C Max: 40.6 °C Max: 46.9 °C Max: 49.2 °C Max: 53.7 °C Max: 57.8 °C Min: 29.1 °C Min: 31.8 °C Min: 34.7 °C Min: 42.8 °C Min: 44.9 °C Min: 49.2 °C Min: 53.5 °C Avg: 28.6 °C Avg: 32.9 °C Avg: 37.2 °C Avg: 44.2 °C Avg: 46.3 °C Avg: 20.8 °C Avg: 55.3 °C 70 C E100 60 C 55 C Max: 28.8 °C Max: 32.2 °C Max: 36.1 °C Max: 42.1 °C Max: 44.0 °C Max: 47.4 °C Max: 50.3 °C 50 C Min: 27.8 °C Min: 30.3 °C Min: 33.3 °C Min: 39.1 °C Min: 40.9 °C Min: 44.6 °C Min: 47.0 °C 45 C Avg: 28.4 °C Avg: 30.9 °C Avg: 34.2 °C Avg: 40.2 °C Avg: 42.1 °C Avg: 45.7 °C Avg: 48.7 °C 40 C 35 C 30 C E100 25 C 5 C Max: 28.9 °C Max: 36.3 °C Max: 40.2 °C Max: 45.9 °C Max: 47.9 °C Max: 49.2 °C Max: 51.2 °C Min: 27.9 °C Min: 32.7 °C Min: 34.9 °C Min: 38.9 °C Min: 40.1 °C Min: 40.8 °C Min: 42.0 °C Avg: 28.4 °C Avg: 34.6 °C Avg: 38.2 °C Avg: 44.0 °C Avg: 45.9 °C Avg: 47.1 °C Avg: 49.1 °C Figure 10. Infrared thermography images of different samples. Figure 10. Infrared thermography images of di erent samples. Table 5 demonstrates the average temperature differences for each mix. The thermal charging results for the samples inclusion nTiO2 showed a different trend to the first set of mixes (mixes without nTiO2). It was observed that incorporation nTiO2 increased the heat transfer rate, which is undesired in terms of thermal insulation properties. The thermal images demonstrated that inclusion of nTiO2 into the composite increased the heat transfer rate compared to the samples without nTiO2. For example, after 15 min the average surface temperature in CS, E50, and E100 samples reached to 55 °C, 52.7 °C, and 48.7 °C respectively. While average surface temperature in the CT, E50T, and E100T samples reached to 56.8 °C, 55 °C, and 49.1 °C respectively that shows an increase in the temperature difference of 1.6 °C, 2.3 °C, and 1.4 °C respectively. Furthermore, the results demonstrated the heat transfer rate of 1.87, 1.76, and 1.38 °C/min for CT, E50T, and E100T respectively that indicates higher rate than the samples without nTiO2. It can be concluded that nTiO2 acts as a filler and changes the pore structures of the cement composite and consequently the thermal charging performance of the matrix. Therefore, in terms of thermal properties, NA substitution with EGA improves the thermal insulation properties of cement composites. This positive effect is attributed to lower thermally conductive and higher porosity of EGA compared to NA. Table 5. The average temperature differences for each mix. Δ (Tave.) Heat Transfer Rate (° C/min) Mix 5 min 10 min 15 min 5 min 10 min 15 min CS 4.40 12.30 26.30 1.58 2.80 1.75 Appl. Sci. 2020, 10, 2246 11 of 14 Table 5 demonstrates the average temperature di erences for each mix. The thermal charging results for the samples inclusion nTiO showed a di erent trend to the first set of mixes (mixes without nTiO ). It was observed that incorporation nTiO increased the heat transfer rate, which is undesired in 2 2 terms of thermal insulation properties. The thermal images demonstrated that inclusion of nTiO into the composite increased the heat transfer rate compared to the samples without nTiO . For example, after 15 min the average surface temperature in CS, E50, and E100 samples reached to 55 C, 52.7 C, and 48.7 C respectively. While average surface temperature in the CT, E50T, and E100T samples reached to 56.8 C, 55 C, and 49.1 C respectively that shows an increase in the temperature di erence of 1.6 C, 2.3 C, and 1.4 C respectively. Furthermore, the results demonstrated the heat transfer rate of 1.87, 1.76, and 1.38 C/min for CT, E50T, and E100T respectively that indicates higher rate than the samples without nTiO . It can be concluded that nTiO acts as a filler and changes the pore structures 2 2 of the cement composite and consequently the thermal charging performance of the matrix. Therefore, in terms of thermal properties, NA substitution with EGA improves the thermal insulation properties of cement composites. This positive e ect is attributed to lower thermally conductive and higher porosity of EGA compared to NA. Table 5. The average temperature di erences for each mix. D (T ) Heat Transfer Rate ( C/min) ave. Mix 5 min 10 min 15 min 5 min 10 min 15 min CS 4.40 12.30 26.30 1.58 2.80 1.75 CT 4.10 16.40 28.10 2.46 2.34 1.87 E50 3.40 14.00 24.00 2.12 2.00 1.60 E50T 4.30 15.60 26.40 2.26 2.16 1.76 E100 2.50 11.80 20.30 1.86 1.70 1.35 E100T 6.20 15.60 20.70 1.88 1.02 1.38 4. Conclusions This experimental work investigated the physical properties as well as the thermal insulation property of cement mortar containing EGA and TiO . The findings revealed that incorporating EGA into the mortar composite causing a significant decrease in density and compressive strength, which was attributed to the porous nature and low compressive strength of EGA. The results also demonstrated that as the EGA content increased, the workability and water absorption of cement composite increased. It is found that the increase in water absorption was due to the high porosity of EGA in comparison to NA. However, the beneficial e ect of the EGA was the decrease in the heat-transferring rate of the cement composite, which indicates the feasibility of a potential reduction in energy consumption in buildings. Moreover, the results demonstrated that inclusion of TiO into the cement composite partially compensated the water absorption and loss in compressive strength. However, it was revealed that addition of nTiO into EGA-cement composites increased the heat transfer rate of the cement matrix and insulation properties as nTiO acts as nanofillers and changes the pores structure in the cement matrix. It can be concluded that in terms of thermal behavior, substitution of NA with EGA decreases the heat transfer rate and consequently improves the thermal insulation properties of the cement mortar. Author Contributions: Conceptualization, A.Y., W.T.; methodology, W.T., M.K., S.W. and C.F.; Investigation, W.T., M.K. and A.Y.; writing—original draft preparation, A.Y., M.K.; writing—review and editing, W.T., C.F., M.K., S.W. and A.Y. All authors have read and agree to the published version of the manuscript. Funding: This research received no external funding. Acknowledgments: The authors gratefully acknowledge the financial support provided by University of Newcastle (2017 UNIPRS and UNRS Central Scholarship). 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Journal
Applied Sciences – Multidisciplinary Digital Publishing Institute
Published: Mar 26, 2020