Early Age Shrinkage of Self-Consolidating Concrete Incorporated with Three Shrinkage-Reducing Components

Self-consolidating concrete (SCC) may experience autogenous and drying shrinkage due to a high content of cementitious materials, lower aggregate content, and smaller aggregate size, resulting in concrete cracking and other durability issues. In order to solve these problems, shrinkage-reducing materials have been proposed and studied, such as polypropylene fiber, lightweight fine aggregate, and expansive admixtures. However, investigation of the combined effect of the aforementioned three shrinkage-reducing materials on SCC is still unreported. This study examined the influence of polypropylene fiber (0.05%, 0.1%, 0.15% of the volume of the concrete), prewetted lightweight aggregate (10%, 20%, 40% of the volume of the fine aggregate), and expansive agent (0%, 8% of the cementitious materials weight) on the shrinkage of concrete during a seven-day curing period under two curing conditions, sealed cure and top-surface exposure cure. The results showed that it was more effective to mitigate early age shrinkage by adding lightweight aggregate alone than by adding polypropylene fiber alone. In the sealed cure (S-Cure) condition, adding 10% lightweight aggregate compensated for shrinkage, and 0.1% polypropylene fiber content exhibited the highest shrinkage reduction. With the top-surface exposure cure (TE-Cure) condition, 20% lightweight aggregate compensated for shrinkage, and 0.15% content polypropylene fiber showed the highest shrinkage mitigation. It showed that the shrinkage of concrete, which has low polypropylene (PP) fiber content (0.05% and 0.10%) and no expansive agent added, was decreased with the increase of lightweight aggregate content. At a high content of PP fiber of 0.15%, the incorporation of lightweight aggregate did not exhibit significant influence on shrinkage reduction.