Mechanical properties of high-ductility magnesium phosphate cement composite cured at low temperatures

In some special applications at low temperature, high ductility, deformation, and durability are required for cement-based composites. Magnesium phosphate cement (MPC) possesses unique properties, including fast hardening at a temperature below 0 °C, high early-strength, and durability. This study investigated the influence of the water-to-binder (W/B) ratio, sand-to-binder (S/B) ratio, and various proportions of fly ash (FA) (as a substitute for MPC) on the workability, compressive strength, and tensile properties of high-ductility MPC-based composites (HDMPCC) incorporating polyvinyl acetate (PVA) fibre and cured at low temperatures. The experimental results revealed that the incorporation of up to 30% FA by mass significantly improved the ductility of the HDMPCC. For an S/B ratio of 0.2, strain corresponding to ultimate tensile stress was found to be more than 1.5%, resulting in better strain-hardening behaviour. Moreover, the HDMPCC composite with 30% FA, W/B ratio of 0.14, and S/B ratio of 0.12 exhibited the highest strain corresponding to peak tensile stress at 0 °C. The strain corresponding to peak and ultimate tensile stress ranged from 0.41% to 2.22%. The highest ultimate tensile stress of about 1.28 MPa was observed for HDMPCC specimens cured at 0 °C, –5 °C and –10 °C.