Experimental Study on Modification of Waste Concrete-Based Geopolymer
Metakaolin is used to modify waste concrete-based geopolymer.The effect of NaOH solution concentra-tion and metakaolin content on the unconfined compressive strength of waste concrete-based geopolymer and modification mechanism were studied.The mineral composition and microstructural characteristics of the geopolymeric products were analyzed by XRD and SEM/EDS.The results show that increasing the NaOH solution concentration and metakaolin content all significantly improve the unconfined compressive strength of waste con-crete-based geopolymer.The reactivity of metakaolin is higher than that of waste concrete,and the reaction gener-ates more colloids to fill the pores in the structure,making the structure denser.The metakaolin modified waste concrete-based geopolymer contains C(A)SH gel and geopolymer gel,which coexists and together promotes the strength development of geopolymeric material.