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Effect of recycled concrete aggregate on mechanical, physical and durability properties of GGBS–fly ash-based geopolymer concrete

Effect of recycled concrete aggregate on mechanical, physical and durability properties of... Low-calcium fly ash (LCFA)- and ground granulated blast furnace slag (GGBS)-based geopolymer concretes are eco-friendly novel concrete to be used as an alternative to traditional OPC concrete. Natural resources are used in the production of cement, while industrial and demolished concrete wastes such as GGBS, LCFA, and recycled concrete aggregate (RCA) are used in the production of geopolymer concrete (GPC) to save natural resources. In this study, the aim is to produce a novel geopolymer concrete with a fairly high strength, up to 85 MPa as compared to the strength achieved so far by other researchers using RCA, GGBS, and LCFA. In addition to this, the emphasis is to utilize the used coarse aggregate obtained from demolished waste. The other objective is to produce the concrete usable in arid regions where water is scarce. These objectives have been accomplished in two steps have followed. In the first step, the preparation of solid and liquid binders was accomplished. The actual solid binders were decided based on trial solid binders consisted of LCFA and GGBS in the ratios of 3:2, 2:3, and 1:4. The liquid binder taken was a solution of silicate and hydroxide of sodium. In the second step, used coarse aggregate after removing the old mortar coating from the surface, was used as a substitute for 25%, 50%, 75%, and 100% of natural coarse aggregate in the GGBS–LCFA-based GPC. The impact of the RCA on the workability, physical and mechanical properties, and durability properties of the produced GPC was determined. The mechanical properties of all the mixes were satisfactory. However, the GPC with sample mix F40G60R0 has proved to be the most satisfactory of all the properties. Sample mix F40G60R50 with 50% RCA and 60% GGBS addition showed the highest compressive strength of 84.31 MPa among all the mixes except sample mix F20G80R0. The presence of RCA in the matrix increased the number of nucleation sites available in the interfacial transition zone (ITZ), resulting in a denser matrix structure. The major difficulty faced was the complete removal of the old mortar coating from the used coarse aggregate to produce RCA. The results revealed that GPC may include a high percentage (up to 100%) of RCA with 60% of GGBS to give sufficient strength for practical applications. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Innovative Infrastructure Solutions Springer Journals

Effect of recycled concrete aggregate on mechanical, physical and durability properties of GGBS–fly ash-based geopolymer concrete

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Publisher
Springer Journals
Copyright
Copyright © Springer Nature Switzerland AG 2022
ISSN
2364-4176
eISSN
2364-4184
DOI
10.1007/s41062-022-00832-w
Publisher site
See Article on Publisher Site

Abstract

Low-calcium fly ash (LCFA)- and ground granulated blast furnace slag (GGBS)-based geopolymer concretes are eco-friendly novel concrete to be used as an alternative to traditional OPC concrete. Natural resources are used in the production of cement, while industrial and demolished concrete wastes such as GGBS, LCFA, and recycled concrete aggregate (RCA) are used in the production of geopolymer concrete (GPC) to save natural resources. In this study, the aim is to produce a novel geopolymer concrete with a fairly high strength, up to 85 MPa as compared to the strength achieved so far by other researchers using RCA, GGBS, and LCFA. In addition to this, the emphasis is to utilize the used coarse aggregate obtained from demolished waste. The other objective is to produce the concrete usable in arid regions where water is scarce. These objectives have been accomplished in two steps have followed. In the first step, the preparation of solid and liquid binders was accomplished. The actual solid binders were decided based on trial solid binders consisted of LCFA and GGBS in the ratios of 3:2, 2:3, and 1:4. The liquid binder taken was a solution of silicate and hydroxide of sodium. In the second step, used coarse aggregate after removing the old mortar coating from the surface, was used as a substitute for 25%, 50%, 75%, and 100% of natural coarse aggregate in the GGBS–LCFA-based GPC. The impact of the RCA on the workability, physical and mechanical properties, and durability properties of the produced GPC was determined. The mechanical properties of all the mixes were satisfactory. However, the GPC with sample mix F40G60R0 has proved to be the most satisfactory of all the properties. Sample mix F40G60R50 with 50% RCA and 60% GGBS addition showed the highest compressive strength of 84.31 MPa among all the mixes except sample mix F20G80R0. The presence of RCA in the matrix increased the number of nucleation sites available in the interfacial transition zone (ITZ), resulting in a denser matrix structure. The major difficulty faced was the complete removal of the old mortar coating from the used coarse aggregate to produce RCA. The results revealed that GPC may include a high percentage (up to 100%) of RCA with 60% of GGBS to give sufficient strength for practical applications.

Journal

Innovative Infrastructure SolutionsSpringer Journals

Published: Aug 1, 2022

Keywords: GGBS; LCFA; Recycled concrete Aggregate; Geopolymer concrete; Workability; Mechanical properties

References