Feasibility study of strain hardening magnesium oxychloride cement-based composites

Magnesium oxychloride cement (MOC) has been studied as an alternative to the ordinary Portland cement. Although MOC based concrete has good strength, early hardening and high bond strength, the applications have been limited due to its disadvantageous chemical nature to steel reinforcement and the natural brittleness. In order to extend this material to wider applications, MOC based engineered cementitious composites (MOC-ECC) was developed. The present paper introduces the fabrication of MOC-ECC with 4 different mixture proportions and a series of tests on the mechanical properties. The tests indicated that the MOC-ECCs have the tensile strain capacity ranging from 5% to 7%, and the tensile strength about 5 MPa. Furthermore, tight crack width control and exceeding compressive ductility were experimentally demonstrated. The addition of fly ash is proved of significant effect on the mechanical properties, including compressive strength, tensile strength, tensile strain capacity, matrix fracture toughness and fiber bridge capacity. The fracture toughness and fiber bridge capacity were used to explain the influence of fly ash to the tensile strain capacity of MOC-ECC in a mesoscopic scale.