Enhancing the internal curing process of self-compacting concrete containing lightweight aggregate and chemical additives

Abstract Internal curing is an important process for high strength concretes such as self-compacting concrete (SCC). A wide range of additives is considered for improving this process and provides necessary water for hydration. Pozzolans such as microsilica and zeolite also can increase the strength and durability. In this study, a range of SAP (0.1%, 0.3% and 0.5% (wt. of cement)) contents were used along with zeolite and microsilica pozzolans. The results implied that 0.1% SAP used in SCC reduced drying shrinkage up to 72.7%. Specimens containing microsilica had the compressive strength increase up to 2.7% and highest durability in terms of conductivity decrease up to 61.3%. In addition, using SAP as a single additive proved to be effective in reducing chloride-ion penetration into the specimens in terms of electrical resistivity increase up to 25.2%. Specimens including both SAP and microsilica had the lowest permeability. Zeolite had a negative effect on permeability compared to the control specimen which SAP reduced this effect by increasing the amount. Microstructure analysis revealed that specimens containing SAP presented a more smooth morphology than the control specimen did. Specimens containing microsilica provided more compact matrix and higher CSH gel development compared to specimens containing zeolite.