Mitigating drying shrinkage and efflorescence in high strength alkali-activated materials through steam curing

Abstract

Abstract The manufacturing of Ordinary Portland Cement (OPC) significantly contributes to global carbon dioxide (CO2) emissions, necessitating the exploration of alternative binders like alkali-activated materials (AAM). Despite its environmental benefits, AAM generally faces challenges such as drying shrinkage and efflorescence, limiting its industrial application. This study focuses on investigating the impact of steam curing on addressing these challenges in high strength slag-based AAM. The results indicates that high strength AAM can be developed by carefully optimizing the activator-to-binder and water-to-binder ratios, and incorporating steam curing. Specifically, a compressive strength of 112.4 MPa was achieved after one day of steam curing, compared to 100.8 MPa after 28 days of standard curing. This demonstrates the ability of steam curing to accelerate strength development of AAM. Furthermore, steam curing proved to be highly effective in reducing drying shrinkage, which was decreased from 17 351 microstrains to 1 440 microstrains. This reduction aligns the shrinkage levels of AAM with those of OPC, addressing a major limitation of AAM. This study also found that efflorescence was notably mitigated, with a significant reduction observed after a 24-hour steam curing period. These findings highlight steam curing as a cost- effective and practical-effective method in improving the performance of AAM. By addressing the key challenges, steam curing facilitates the broader adoption of AAM in sustainable construction practices.

Keywords

• Alkali-activated materials
• Steam curing
• Drying shrinkage
• Efflorescence
• Low-carbon