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

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. 普通硅酸盐水泥的生产是全球二氧化碳排放的重要来源, 因此, 急需探索碱激发材料等替代胶凝材料。尽管碱激发材料具有显著的环保效益, 但其在干燥收缩和泛碱等方面的问题限制了其在工业中的广泛应用。本研究旨在探讨蒸汽养护对高强度矿渣基碱激发材料在上述问题中的影响。研究结果表明, 通过调整激发剂/粘合剂及水/粘合剂的比例, 并引入蒸汽养护, 可以成功研发出高强度的碱激发材料。具体而言, 该碱激发材料在经过1天的蒸汽养护后, 抗压强度可达112.4 MPa, 而标准养护条件下需28天才能达到100.8 MPa。这表明蒸汽养护有助于加速碱激发材料的强度发展。此外, 蒸汽养护在减少干燥收缩方面表现出显著效果, 将干燥收缩从17351 με降至1440 με。这使碱激发材料的收缩率达到了普通硅酸盐水泥的水平, 解决了其一个主要缺陷。研究还发现, 经过24小时的蒸汽养护后, 泛碱现象明显减轻。这些发现表明, 蒸汽养护是一种经济, 实用且有效的方法, 能够显著提升碱激发材料的性能。通过解决干燥收缩和泛碱等关键问题, 蒸汽养护有助于推动碱激发材料在可持续建筑领域的更广泛应用。