Influence of Activators and Admixtures on Rheology of Geopolymer Slurries for Well Cementing Applications

Abstract

Abstract Geopolymers are considered an alternative to Ordinary Portland Cement due to various reasons regarding some of its shortcomings and the high carbon dioxide footprint associated with its production. Superplasticizers are admixtures that plasticize and fluidize the cementitious slurry by means of steric electrostatic mechanisms that apply repulsion forces between the slurry particles. They are commonly used to improve the workability of cement and geopolymer pastes. However, the most developed superplasticizers are for Ordinary Portland cement. Electrokinetic potential measurements of the ingredients can be used in the evaluation of superplasticizers. Therefore, the effect of the utilization of two hardeners and the effect of the electro-kinetic potential of four admixtures, on the rheological properties of a rock-based geopolymer slurry are presented. These four admixtures are examined to investigate their applicability to being superplasticizers for conventional geopolymers. The results show that naphthalene-based admixtures could be considered effective superplasticizers for the rock-based geopolymer slurry. Although they reduce the slurry's yield stress and API gel strength by showing the highest absolute zeta potential value, the viscous behaviour of the geopolymer slurries showed an increase. Hence, electro-kinetic potential measurements could be used to evaluate the applicability and performance of the admixtures on the rheological properties of the geopolymer slurry.