One year geopolymerisation of sodium silicate activated fly ash and metakaolin geopolymers.

Abstract This paper presents the evolution of mechanical and chemical properties of sodium silicate activated fly ash and metakaolin geopolymers in one year time scale. The initial curing protocols are considered, which were chosen based on the isothermal heat release properties of both reaction systems. Increasing initial temperature contributes to the cumulative heat release, strength development and zeolite formation of both geopolymers, especially the fly ash based, but results in slightly worse pore characteristics. The formation of zeolite is rapid, indicating a simultaneous process with geopolymerisation. During sample handling and aging, natural carbonation took place. Two kinds of carbonation processes are detected: reaction of CO 2 with mobile alkalis on the one hand and with framework oxygen atoms of the alunimosilicate gels on the other hand. [ABSTRACT FROM AUTHOR]