Expansion behavior and microstructure change of alkali-activated slag grouting material in carbonate environment

Abstract

Alkali-activated slag materials (AASM) are restricted from widespread use in the field of structural materials because of shrinkage. Nevertheless, AASM have excellent rheological and mechanical properties, but their properties and microstructure are rarely studied in a carbonate environment. In this study, according to the alkalinity of 4 wt%, 5 wt%, and 6 wt%, alkali-activated slag grouting material (AASGM) specimens were prepared by mixing sodium silicate with a modulus of 2.0 and slag . The samples were immersed in pure water and sodium carbonate solutions with a concentration of 1–4 wt% for 90 days. The expansion rate, mass change, mechanical properties, and microstructure of the samples were measured and analyzed. The results indicate that the main gel products were C-A-S-H gel and amorphous calcium carbonate. The AASGM samples showed slight expansion, a small increase in mass, essentially unchanged compressive strength, and good anti-carbonate corrosion performance. The insights into the property evolution and microstructure provided by this study will play a fundamental role in further understanding, controlling and even utilizing the AASGM.