Assessment of Interface Characteristics and Durability Aspects of Manufactured Sand (M-sand) in Engineered Cementitious Composites

Concrete structures usually tend to crack and cause several distresses, thus resulting in regular maintenance activities. Engineered Cementitious Composites (ECC) in structural applications are becoming popular due to their cracking resistance and deformability. However, the conventional mix design of ECC with silica sand levied a negative influence on cost and drying shrinkage, thereby affecting their practical implementation. In this study, the matrix properties and interface characteristics of ECC tailored with Manufactured sand (M-sand) replacing the river sand at varying proportions were investigated. The study conducted mechanical characterization, matrix fracture toughness, and single-crack tension tests to evaluate the micro-mechanical properties and fiber-matrix interaction. Furthermore, the shrinkage characteristics and permeability properties of ECC mixtures were also evaluated at various replacement levels of M-sand. The natural river sand adhered to the finer gradation, characterized by a fineness modulus of 1.63, while the M-sand exhibits a coarser gradation, having a fineness modulus 2.74. The experimental results showed that the ECC mixtures with M-sand improved the compressive strength (up to 29%) at 100% replacement level and marginally influenced the tensile strength. However, the tensile ductility and fiber bridging characteristics showed a noticeable decrease as the percentage replacement increased in the mixtures. On the other hand, the drying shrinkage of all M-sand ECC mixtures showed a notable reduction irrespective of the curing ages. It is also seen that the permeability properties were slightly increased compared to that of the control mixture. In summary, the study observed a trade-off between mechanical strength and tensile ductility, highlighting the effects of fiber-matrix interface tailoring on the overall performance of ECC mixtures with M-sand for various structural applications.