Mechanical property and durability of engineered cementitious composites (ECC) with nano-material and superabsorbent polymers

To improve the tensile capacity and control crack width, engineered cementitious composites (ECC) are considered as a promising strategy for structural reinforcement. However, the shrinkage deformation of ECC threatens the structural integrity and durability of the concrete structure. In this study, a novel ECC with low shrinkage and high ductility is designed by utilizing the synergistic effect of nano-materials and superabsorbent polymers (SAPs). Compared with plain ECC, the application of SAP decreases the compressive strength and ultimate tensile strength of ECC, whereas it increases the strain capacity by 56.0%-81.3%. Meanwhile, the nano-enhanced ECC mixed with SAP exhibits lower autogenous shrinkage and drying shrinkage in comparison with plain ECC, especially for small-sized SAP. Although the incorporation of SAP reduces the mechanical properties and impermeability of ECC due to the coarsening of the pore structure, further application of an appropriate amount of nano-SiO2 (NS) can effectively increase the content of hydration products in the matrix, thereby improving the mechanical properties and durability of ECC mixed with SAP. However, as NS is more likely to agglomerate on the surface of large-sized SAP, the incorporation of excessive amount of NS leads to a decrease in the mechanical properties and impermeability of ECC. A low-shrinkage, high-toughness nano-engineered ECC developed in this study provides a theoretical basis and guidance for the application of ECC in practical engineering.