Early-age activation of cement pastes and mortars containing ground perlite as a pozzolan

Perlite is a natural pozzolan abundant in several countries which are major producers of cement. This makes perlite attractive for producing sustainable concretes. Strength development and heat evolution of perlite-containing mixtures, and the influence of chemical and thermal activation on their early and later age properties were investigated using five activator chemicals and four curing temperature-duration combinations. Chemical activation could increase the 1-day, or 3-day compressive strengths of 25% perlite mortars to above the cement-only control but was not very beneficial to 50% perlite mixtures. Thermal activation could increase strength at ages up to 28 days, and even above the room-temperature control at 1 day. Perlite content affects the maximum value of the isothermal calorimetry heat evolution rate but not its time of occurrence. Chemical and thermal activation influence both the height of the rate peak and its timing, which are linearly correlated for activated or non-activated pastes with a given perlite content.