Properties of fresh and hardened geopolymer-based grouts

Abstract

A geopolymer blended with fly ash (FA) and ground granulated blast-furnace slag (GGBS) was designed to investigate the properties of geopolymer (GP) – based grouting materials from different aspects. The workability, i.e. flowability, bleeding capacity, setting time and change of viscosity with time, as well as the compressive strength and microstructure of the GP-based grouts were investigated. The ratios of GGBS to FA and the concentration of sodium hydroxide were 0.2 - 1.0 and 0.5 - 4.0 M, respectively. The results show that GGBS enhances the flowability, while FA and sodium hydroxide enhance the stability of fresh grouts. The setting time reduces as the ratios of GGBS to FA and sodium hydroxide concentration increase. Sodium hydroxide concentration has a greater effect on the change of viscosity with time compared to the ratios of GGBS to FA. FA and sodium hydroxide reduce the compressive strength of hardened grouts, while GGBS improves their compressive strength. By adjusting the ratios of GGBS to FA and the concentration of sodium hydroxide, the setting time of GP-based grouts could be tailored from 0.5 to 5.5 h, the compressive strength after 28 days was up to 7.48 MPa, and the bleeding capacity is less than 2.5 %. The optimum GGBS to FA ratio and sodium hydroxide concentration is 0.8 and 2.0 M, respectively, which can meet the performance requirements for grouting reinforcements in grouting engineering.