Abstract
Despite the elimination of cement endowing engineered geopolymer composite (EGC) with a certain carbon-benefits, the use of traditional activators including sodium hydroxide and sodium silicate still limits its advancement towards further low carbon. On the other hand, how to effectively deal with the increasing accumulation of red mud (RM), a highly alkaline solid waste, has been a longstanding goal of environmental protection community. With the purpose of addressing the above two issues, this study explanatorily evaluates the feasibility of recycling waste RM as activator to develop EGC from the aspects of the mechanical properties, tensile cracking behavior, microstructure, and sustainability. The findings indicated that, up to 80% RM utilization as activator maintained a decent compressive strength around 40 MPa and high tensile strain capacity over 3%, and excellent cracking-control ability (with a crack width of less than 150 μm). SEM analysis revealed that RM increased the amounts of unreacted particles and porosity, which was unconducive to the mechanical strength but favored the tensile strain. Sustainability analysis revealed that the current EGCs achieve a carbon-reduction of above 65% and energy-reduction of above 22.1%, respectively, compared to the typical engineered cementitious composite (M45-ECC). The current findings can offer a promising idea for further improving EGC sustainability and decreasing contamination to the environment of waste RM.
Published Version
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