Effects of combined expansive agents and supplementary cementitious materials on the mechanical properties, shrinkage and chloride penetration of self-compacting concrete

Abstract

Abstract In this study, the effects of incorporating expansive agent on the early-age mechanical properties, shrinkage characteristics and durability tests of self-compacting concrete (SCC) with different supplementary cementitious materials (SCMs) are investigated. Fly ash (FA), blast furnace slag (BFS) and metakaolin (MK) are added as partial replacement for cement respectively, while three different kinds of expansive agents are introduced in SCC at 15 wt%, 5 wt% and 1 wt% by cement weight. Results show that SCC presents a slightly lower compressive strength and modulus of elasticity compared to those of reference specimens at early ages, while the pozzolanic reactivity of SCMs lead to an increase the mechanical properties in the long-term strength development. The incorporation of combined magnesia expansive agent and liquid expansion agent indicates a significant reduction in the measurement of autogenous shrinkage and drying shrinkage. Additionally, the chloride ion penetration resistance of SCC is enhanced. Moreover, the combination of magnesia and liquid expansion agents refines pore structure and induces compensation for the auto-desiccation which results in high efficiency in the shrinkage reduction.