Mechanical properties of high ductile magnesium oxychloride cement-based composites after water soaking

摘要

Applications of magnesium oxychloride cement-based concrete in civil engineering are limited due to material's poor water resistance and inherent brittleness. For improvement, a new kind of material, magnesium oxychloride cement-based engineered cementitious composite (MOC-ECC), was developed. This paper introduces the effects of fly ash and polyethylene fibers incorporations on the fluidity, tensile behavior and compressive properties of MOC-ECC. The test results indicated that MOC-ECC exhibits outstanding strain hardening and multi-cracking characteristics with tensile strain capacity up to 8% and tensile strength over 7 MPa. More importantly, to explore the combined influences of fly ash and polyethylene fiber on the water resistance of MOC-ECC, XRD and SEM were used to analyze the variations of chemical composition and microstructure, and three-point bending test and single crack tension test were conducted to obtain the fracture toughness and fiber bridging capacity, respectively. An explanation to the mechanisms of the enhanced mechanical property and water resistance is presented at microscopic and mesoscopic scales.