Abstract:
In order to address the brittleness and durability issues of coral aggregate concrete, seawater coral sand engineered cementitious composites (SCECC) was prepared by using the regional raw materials located in islands and reefs. The effects of different aggregate types, maximum grain size and fineness modulus on the compressive, tensile properties and crack control ability of ECC were experimentally investigated. The results show that with the decrease of the fineness modulus of coral sand, the compressive strength of SCECC first increases and then decreases, which maximizes (63.3 MPa) at SCECC with the maximum grain size of 2.36 mm. Reducing the maximum grain size of coral sand results in improved tensile performance to varying extents. SCECC with a maximum grain size of 0.60 mm exhibits the best tensile properties, and its initial cracking strength, tensile strength and ultimate tensile strain are 2.29 MPa, 4.11 MPa and 5.15%, respectively. Meanwhile, its average crack width approaching strain capacity is controlled at 81 μm. Compared with tap water-quartz sand ECC, SCECC possesses higher compressive strength and more rapid development of early strength (its 7 days compressive strength can arrive at 73%-78% of 28 days compressive strength). The failure modes of aggregate and polyvinyl alcohol (PVA) fiber in these two ECCs are different, resulting in slightly lower tensile strength, elastic modulus and crack control ability at peak strain, but significantly enhanced tensile ductility of SCECC.