Abstract
This article presents a comparison between the impact of different mineralogical compositions of natural pozzolans for geopolymer synthesis. Beyond an optimum silica modulus, the compressive strength either increases on low rate or decreases with age. The presence of zeolite minerals enhances the reactivity of natural pozzolans. In contrast, the presence of calcite can lead to the incorporation of calcium into the reaction products. At the same time, the carbonate can enhance the formation of sodium carbonate, which can deplete the alkalis and water from binder gel, thereby reducing the rate of compressive strength development. In severe cases, the crystallization pressure of sodium carbonate can cause a complete disintegration of the structure. These effects are pronounced for samples outside the optimum silica modulus range and for low reactive pozzolans.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
