Tensile creep behavior of Alkali-activated slag concrete incorporating lightweight aggregate

This study aims to investigate the effect of pre-wetting lightweight aggregate (LWA) on the tensile creep of alkali-activated slag concrete (AASC) for 14 d. Three replacement rates of natural coarse aggregate with LWA were used in this study, including 0, 50%, and 100%, and the Ordinary Portland cement concretes (OPCCs) mixed with LWAs were considered as control samples. The results showed that the tensile creep of the AASCs was higher than those of OPCCs with the same LWA content. The incorporation of pre-wetting LWA significantly reduced the modified autogenous shrinkage and tensile creep of the AASCs, and the magnitudes were continuously declined with the increase in LWA contents. The early age of 1 d dominated more than 70% of the total tensile creep of the AASCs for 14 d. Furthermore, pre-wetting LWAs had a greater effect on decreasing tensile creep for the AASC system than the OPCC system. Meanwhile, the creep/shrinkage ratio of the AASCs was declined by the addition of pre-wetting LWAs. In addition, the cracking age of the AASC was desirably delayed by adding pre-wetting LWA, and the effect was more noticeable with the increase in LWA contents.