Mechanical Properties and Microstructure of Alkali-Activated Slag Grouting Materials Exposed to Flowing NaHCO3 Solution

AbstractThe durability of alkali-activated slag grouting materials (AASGMs) has attracted significant research attention. This paper investigated the mechanical properties and microstructure of AASGMs mortars and pastes immersed in a flowing 5% NaHCO3 solution. Compared with the strengths of AASGMs immersed for 3 days, the flexural and compressive strengths of AASGMS immersed for 56 days increased by 11.1% and 37.8%, respectively. The leaching depth of AASGMS immersed for 56 days was 0.627 mm. The AASGMs had good antiflowing NaHCO3 solution deterioration performance. The leaching process of AASGMS in flowing NaHCO3 solution was divided into three stages: (1) neutralization of residual alkali in gel pores; (2) decalcification of calcium aluminate silicate hydrate (C-A-S-H) gels in the surface and intermediate layers to form calcium carbonate and silica gels; and (3) leaching of calcium and silicon in surface layers from calcium carbonate and silica gels.