The Application of Different Curing Models to the Strength Development of High Calcium Fly Ash Geopolymer Incorporating Limestone

Abstract

One of the issues in geopolymer specimen is the requirement for heat curing treatment temperature. The use of a material with high calcium content is one alternative to overcome this problem. However, the addition of calcium tends to alter the basic geopolymer matrix being similar to the basic matrix in normal concrete, which requires a water addition during curing process. This research aims to investigate the effect of different curing models to the strength development of fly ash geopolymer specimens with limestone inclusion. Class C fly ash was used as primary material. The blended sodium silicate and 10 Molar NaOH were used as alkaline activator. Three different curing models were applied, i.e. 24-hours water immersion, watering once a day, and watering twice a day, respectively. The results show that the addition of 30% limestone under watering once a day curing models gives the best result with the strength of 32.54 MPa. The limestone inclusion significantly affects the strength development of geopolymer mortar strength. It also slightly increases the water requirement during curing process to achieve its structural integrity. This is might be attributes to the changes in geopolymer matrix due to the addition of limestone.