Mechanics And Deformation Performances Of Internal Curing Cement-Based Materials

The high-performance cement-based materials shrink seriously and easy to crack. Curing is one of the most important factors that affect the performance of the cement-based materials. In this paper, the purpose of internal curing was achieved by the methods of incorporating super-absorbent polymer (SAP) in the mortar. The mechanical properties were researched in the paper. Based on this, more work has been focused on the influences of SAP and mineral admixture to the shrinkage. The relationship between the internal humidity and shrinkage has been analyzed and the hydration performance has been studied.The study chooses two ways to adding water. First, keep the water-binder ratio constant. Second, put additional water into the mortar. The research shows that the strength of mortar declined slightly as there is no additional water in the mortar. But appropriate dosage of SAP can improve the compressive strength. The strength decreased obviously while introducing additional water to the mortar.SAP can inhibit the autogenous shrinkage and drying shrinkage. While the mortar with additional water, autogenous shrinkage decreased obviously and drying shrinkage increased as the amount of water increase, which is contrary to the no additional water mortar.Internal curing can improve the internal relative humidity and which increased with the amount of SAP increase. That can explained why SAP can decrease the shrinkage. Mineral admixture also affect the shrinkage, the shrinkage of the mortar mixed with 30% fly ash and 0.4% SAP is less than other mortar systems. By measuring the weight of chemical combined water, arrive at a conclusion that internal curing can improve the degree of hydration and additional water improves it more apparent. SEM and XRD experiments also verified the conclusion.