Effect of ultrafine red mud on the workability and microstructure of blast furnace slag-red mud based geopolymeric grouts

Abstract

Aims at improving the utilization rate of red mud and preparing a low-cost grouting material for underground engineering, the ultrafine red mud was adopted to prepare a slag-red mud based grout, and its fresh and hardened state properties were investigated comparing with the coarse red mud. The results showed that the incorporation of red mud could prolong the setting time and decrease the viscosity and thixotropy of slag-based geopolymeric grout, and ultrafine red mud has a better decrement effect. Ultrafine red mud has an enhancement effect on the slurry stability. The mechanical strength decreased with the adoption of red mud, while the ultrafine red mud has a higher mechanical strength than coarse red mud. The microstructure analysis showed that red mud plays a filling role in the geopolymerization process, and mechanical activation could increase the reactivity of red mud, furthermore, the iron component in ultrafine red mud could take part in the geopolymerization process. The results shed light on the utilization of red mud and the application of geopolymer in grouting engineering.