Effect of water pressure and notch depth on the fracture properties of ECC under shear loading

Engineered cementitious composites (ECC) were well-suited for hydraulic structures owing to their high durability and their crack control capability. However, hydraulic structures could experience significant shear loads. Therefore, shear fracture tests of concrete and ECC were conducted under different water pressures (0, 0.1, 0.2, 0.3, and 0.4 MPa) and notch depths (40 and 80 mm) using unilateral notched half-symmetrical specimens. The results indicated that at all notch depths, increasing water pressure led to a consistent reduction in crack initiation load, critical load, peak load, and overall critical fracture toughness. At a notch depth of 80 mm, the reduction observed in concrete was significantly greater than that in ECC, primarily due to the higher brittleness of concrete and the rapid crack propagation along the aggregate-mortar interface. The fiber-bridging effect in ECC effectively suppressed crack propagation and enhanced crack stability. Moreover, increasing the notch depth further reduced fracture parameters.