Mechanical properties and microstructure of basalt fiber-biobased- basic magnesium sulfate cement

A low-carbon composite termed basalt fiber (BF)-biobased-basic magnesium sulfate cement (BMSC) is proposed. It utilizes recycled wood fiber (RWF) and BF as lightweight fillers and reinforcements. The microscopic mechanism of the effect of RWF and BF on the fluidity of BMSC paste and the mechanical properties of the hardened samples is discussed. The microstructure, physical phase analysis and image identification semi-quantification demonstrated that RWF enhances the development of the 5·1·7 phase. After further incorporation of BF, the fluidity and dispersion of the paste then decrease. However, the magnesium cement matrix–RWF–BF system form in the BMSC turns the single-fiber reinforcement into a composite reinforcement. It improves the mechanical properties of the composite, especially the flexural strength, even though the addition of RWF made the BMSC composite less dense. In addition, the biobased-BMSC is influenced by the coupling-competition mechanism, which is reflected by the pore structure and mechanical properties. It indicates that the low-carbon composite has the potential for carbon sequestration and the development of environmentally friendly additives for improving the performance of BMSC.