Effect of shrinkage-reducing admixture and expansive agent on mechanical properties and drying shrinkage of Engineered Cementitious Composite (ECC)

In order to reduce the drying shrinkage strain of traditional ECC and diminish the shrinkage differences between concrete and PVA (PolyVinyl Alcohol) fiber, this paper designs eighteen groups mix proportions based on Taguchi Methods. The influences of water-binder ratio, sand-binder ratio, fly ash content, expansive agent content, shrinkage-reducing agent content and PVA fiber volume content on the compressive strength, tensile properties and drying shrinkage are researched. In addition, the effect of PVA fiber on the crack resistance is investigated. The results indicate that the shrinkage strain of ECC increases with the raising of water-binder ratio, and decreases with the increasing of sand-binder ratio, fly ash content, expansive agent, and shrinkage-reducing agent; The anti-cracking performance is significantly improved along the fiber volume content changes, but it has little effect on ECC shrinkage strain. The compressive and tensile strength of ECC will greatly reduce with the increasing of shrinkage-reducing agent, rather, the compressive strength of ECC will enhance with the increase of expansive agent; But the expansive agent will lower the tensile strength and ultimate tensile strain. In the scope of this research, the water-binder ratio, sand-binder ratio, and fly ash content is about 0.25-0.33, 0.33-0.45, and 65% respectively. The research generated a set of reliable and valuable test data for the researchers and practical structural engineers in the field of ECC drying shrinkage.