Rheology control of low-density geopolymer paste for well cementing application: Synergistic effects of precursor fineness and sodium gluconate

The precise regulation of rheological properties in low-density cementitious paste is crucial for successful deepwater well cementing operations, particularly when implementing innovative geopolymer technology. This study investigated the synergistic effects of precursor fineness and sodium gluconate (SG) addition on the rheological properties and performance characteristics of low-density geopolymer paste. The results showed that the ultrafine fly ash and slag additions reduced liquid film thickness of the precursor particles, and consequently enhanced both yield stress and plastic viscosity of the paste. Despite exhibiting shear-thickening behavior, the homogeneity and stability were improved. The reaction kinetics was accelerated, achieving the maximum 1-day compressive strength of 18.1 MPa. Formation of more C-(A)-S-H gel phase in the binder effectively transformed capillary pores into gel pores, resulting in a more compact structure. In comparison, the SG addition demonstrated the opposite rheological modification effects to improve the flowability of paste, without having a notable retardation effect on the setting time. The combination of optimized precursor fineness and SG addition presents a technically viable solution for deepwater cementing applications requiring precise rheological control for low-density geopolymer paste. • Low-density of geopolymer paste for well cementing application was successfully developed. • Effects of precursor fineness and sodium gluconate on rheology of geopolymer were investigated. • Ultrafine fly ash and slag additions reduced liquid film thickness. • Both yield stress and plastic viscosity of paste were enhanced, which improve paste stability.