Dual-functional Polymer-Modified Magnesium Oxychloride Cement Pastes: Physico-mechanical, Phase, and Microstructure Characterizations

Alternative and low CO2-binders with reduced energy consumption have recently attracted attention in building material technologies. Therefore, the inclusion of VAC copolymer emulsion [copolymerization of vinyl acetate (VAc) and vinyl versatate (VeoVa 10)] in varying amounts (2%-10%) as a bonding copolymer in the alternative magnesium oxychloride cement (MOC) pastes was studied as a redispersed emulsion phase in matrices. After air-curing at intervals up to 28 days, the physical and mechanical properties of MOC-VAC composite samples were investi-gated in terms of workability, zeta potential, setting times, bulk density, apparent porosity, and compressive strength. In addition, the phase and microstructure of prepared composites were investigated via Fourier-transform infrared spectroscopy (FTIR), Raman, X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). Results revealed that polymer-modified MOC pastes achieved high-strength building units up to 50 MPa at early ages of air-cured samples with a density of 1000-1200 kg/m(3) (1.0-1.2 g/cm(3)). Scanning electron microscopy microstructural analysis reveals that the whisker-shaped crystals of magnesium oxychloride tangle together to form a compact and rigid structure. In conclusion, the VAC copolymer acts as a bonding agent in MOC composites and produces a lightweight rigid structure via air entrapment, as well as having a virtually plasticizing effect.