Abstract: To improve the inherent brittleness and poor water resistance of the magnesium oxychloride cement (MOC) based composites, ultra-high toughness MOC composites (MOC-UHTC) was developed with the help of specially treated polyethylene (PE) fibers under the guidance of micromechanical design principle. The tensile, compressive and single-fiber pullout tests of materials in the four replacement ratio of fly ash (20%, 30%, 40% and 60%) were conducted. The effect of the replacement ratio of fly ash on the mechanical properties, water resistance of the materials was analyzed. And the phase composition of hydration products and the microstructure of the composites in different replacement ratio of fly ash was analyzed by XRD and SEM, respectively. The results indicate that MOC-UHTC exhibits outstanding strain hardening behavior and multi-cracking response. The tensile strain capacity of MOC-UHTC ranged from 5% to 8% with the tensile strength from 4 MPa to 7 MPa. The tensile and compressive strength retention coefficient of the composites exceeded 0.7 and 0.8 respectively, indicating that the water resis-tance was improved due to the addition of fly ash and PE fibers. Moreover, the tensile strain capacity had a certain increase after the composites immersed in water.
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2019, Vol. 33 
