Freeze–Thaw Durability and Shrinkage of Calcium Sulfoaluminate Cement Concrete with Internal Curing

Numerous applications in civil and transportation engineering require concrete with high early strength and good durability properties. Limited studies have revised the performance of high early-strength concrete prepared with calcium sulfoaluminate (CSA) cement and internal curing technology. This study evaluates the strength and durability properties of four concrete mixtures designed with low and high cement contents, incorporated with and without internal curing. Compressive and split tensile strength, autogenous and drying shrinkage, and freezing and thawing resistance were evaluated. High early-strength concrete mixtures with internal curing achieved lower strength and improved durability (shrinkage and freezing and thawing resistance) in comparison with their analogous control mixtures. All concrete mixtures obtained compressive strength higher than 17 MPa (2,500 psi) within the first 4 h. Concrete mixtures with high cement content showed less contraction (<200 με) than their analogous control mixtures. The internally cured concrete mixture with low cement content exhibited slight expansion instead of shrinkage. Finally, the freezing and thawing resistance showed great improvement because no or little damage was observed in the internally cured concrete mixtures. The internally cured concrete specimens overcame 300 cycles, whereas the control mixtures reached maximum 164 cycles. The internally cured mixtures with low and high cement contents showed a final relative dynamic of elasticity of 79.7% and 99%, respectively. Based on these results, using CSA concrete for repair works could be feasible with internal curing technique.