Dual-functional polymer-modified magnesium oxychloride cement pastes: Physico-mechanical, phase, and microstructure characterizations

Abstract

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 investigated 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/m3 (1.0–1.2 g/cm3). 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.