Development of low temperature lightweight geopolymer aggregate, from industrial Waste, in comparison with high temperature processed aggregates

Abstract

Abstract The purpose of this study is the development of new aggregates based on geopolymer formulations in order to replace commercial lightweight aggregates (LWAs), which require high energy consumption due to its industrial sintering process. Geopolymers are innovative materials which are synthesized at low temperature and which exhibit efficient mechanical and thermal properties. Thus, the feasibility of producing geopolymer aggregates was investigated. Numerous metakaolins and by products of bricks production were applied in a porous geopolymer formulation using sodium silicate solution, and silica fume as pore forming agent. Among 30 compositions, four mixtures exhibit suitable water resistance properties to replace LWAs. Then, these mixtures were investigated by in situ Fourier Transform InfraRed spectroscopy study. Thermal and mechanical properties of the synthesized samples were also determined by Laser Flash method and compressive test (crushing tests for the aggregates). Next, the microstructure of the porous aggregates was evaluated through image analysis, SEM observations. Finally, various critical environments such as fire and freeze-thaw test were applied on the aggregates. Geopolymer aggregates reveal thermal properties, density values, water absorption rate and also a crushing behavior similar to the commercial aggregates. They remained constant after a freeze-thaw test and fire test. Consequently, this work has demonstrated the great potential of geopolymer aggregates to replace LWAs, since they exhibit similar properties and more eco-friendly production process.