Hot-pressed geopolymer: Dual effects of heat and curing time

Hot-pressed curing of geopolymers introduces an efficient fabrication of almost pore-less and high strength binders with a minimum usage of alkali activator in an extremely short time. This study presents the dual effects of temperature and curing time on kinetics and mechanical properties of VA-based hot-pressing geopolymer. Moreover, the effects of elevated temperature on the aluminosilicate precursors dissolution and the pressure loss of the hot-pressed geopolymer are investigated. It is observed that increment in temperatures and time improves the dissolving trends of the aluminosilicates. Furthermore, pressure loss of the hot-pressing system is associated with the liquid phase removal and gelation of particles; and, a successive repressing of mixture to the initial condition reduces the porosity of the matrix significantly. The increase in curing temperature of the hot-pressing system is the key point in acceleration of the geopolymerization kinetic, however, curing time is essential in stabilization of the reaction.