Effect of Organic Retarders on Fluid-State and Strength Development of Rock-Based Geopolymer

Abstract

Granite waste is rich in aluminum and silicate has the potential of turning to geopolymer material after mixing with an alkali solution. One of the challenges in developing a geopolymer is to select a suitable retarder to adjust the target pumpability while maintaining workability and followed by a proper strength development rate. In this study, the effect of five selected organic retarders on workability, viscosity, and compressive strength has been examined. Sucrose, a calcium chelator, gluconic acid, sodium lignosulphonate, and ionic liquid were selected as candidate retarders. The experiments were carried out at room temperature according to American Petroleum Institute (API) standards for testing well cement. The tested retarders indicated a secondary effect on fluid-state properties. The reasons for the secondary effect are due to either the change in the pH of slurries or the interaction between ions released from the retarder and the geopolymer precursor. Gluconic acid and sucrose provided a longer setting time, while they significantly lowered the strength development in the short-term. Lignosulfonate had less impact on workability. However, it reduced viscosity and yield stress. All retarders influenced the strength development rate, but the sodium lignosulfonate, chelator, and ionic liquid had a negligible impact on final strength after 14 days of curing.