Internal Curing in High Performance Concrete: Effect of Lightweight Aggregate on Shrinkage and Salt Frost Durability

摘要

High performance concrete (HPC) consisting of low water-binder (w/b) ratio and supplementary cementitious materials (SCM) is more prone to shrinkage cracking if subjected to external deformation restraint. The effectiveness of using lightweight fine aggregate (LWA) for autogenous shrinkage reduction is being studied along with implications on salt frost durability. HPC consisting of 0.33 w/b ratio and cementitious replacement level up to 50% by slag cement and natural sand replacement level by LWA of up to 50% is investigated. Results indicate that these concretes exhibit excellent salt frost resistance provided the HPC is sufficiently air entrained. The mitigation of autogenous shrinkage by LWA is analyzed by comparing the spacing of LWA particles in cement paste and the flow distance of retained moisture in LWA to the adjacent paste.