Mechanical performance of MgO-doped Engineered Cementitious Composites (ECC)

Engineered Cementitious Composites (ECC) is a special class of high performance cement-based composites featuring high tensile deformation capacity (>2%) and tight crack opening (typically <100 μm). It is reported that doping ECC with a small proportion of reactive magnesia (MgO) can significantly enhance the water impermeability and self-healing performance. However, the present knowledge on how the MgO affects the mechanical performance of ECC is very limited. In this investigation, the influence of MgO (0–10% by weight of cement) on the workability, compressive strength, crack pattern, water permeability and tensile performance of the MgO-doped ECC were comprehensively evaluated. It was concluded that a higher MgO proportion yielded higher/better tensile strength, crack control capacity, water impermeability and workability, though it also led to slightly lower compressive strength, elastic modulus and fracture toughness in ECC. Additionally, doping 6% MgO in ECC was found to be optimal for enhancing the tensile deformation capacity, which is consistent with the prediction from the micromechanical model. These findings shed light on the design of sustainable ECC in the future.