Synthesis of sustainable one-part geopolymers for well cementing applications

Abstract

This work describes the synthesis of a novel one-part granite-based geopolymer mix design for well cementing applications by screening and improving the early-age performance of the geopolymers. The dissolution rate of granite and potassium silicate (K2SiO3) is slightly enhanced when they are blended, compared to the situation when granite was mixed with alkali solution. It was revealed that the chemical composition of granite requires modification. Ground granulated blast-furnace slag (GGBFS) was incorporated up to 90% of total weight (wt.%) within the solid precursor to find out the optimum design, based on its effect on fluid-state and solid-state properties. Pumpability and strength development of the slurries were studied to establish the applicability of the mix designs. To further characterize the final products, the mineralogy and morphology of the specimens were examined. The use of GGBFS, to modify the chemical composition of the granite, reduces the pumping time significantly. Moreover, the use of GGBFS increases the density and initial consistency value of the slurry proportionally to the increase in GGBFS content. Additionally, a threshold effect was observed in the mechanical strength development. The higher the GGBFS content (up to 50 wt%), the higher the early-age compressive strength. The highest measured compressive strength for the neat rock-based geopolymer recipe was around 6 MPa within 1-day to 7-day for a mix of 47 wt% GGBFS to the solid precursor, while its optimized mix was around 12 MPa within the same period.