Optimization of mechanical properties and water resistance of sawdust-magnesium oxychloride cement composites based on orthogonal tests
Yuanze Li, Huagang Zhang, Qiang Fang, Tao Yu, Jiaojiao Yang, Wenchao Li
Abstract
Sawdust-magnesium oxychloride cement composites (SMOCC) are new low-carbon and environmentally friendly building materials . Its development not only reduces carbon dioxide emissions, but the use of sawdust can improve wood utilization rates and play important roles in protecting the environment. Nonetheless, SMOCC's performance is affected by various factors, and its overall sustainability remains to be comprehensively evaluated, which limits widespread application. For this reason, the effects of different factors (including MgO/MgCl 2 molar ratio , MgCl 2 solution concentration, and content of NaH 2 PO 4 ) on the performance of SMOCC were initially obtained through single-factor experimental analysis. Next, multi-factor experiments were performed using the Taguchi orthogonal experimental method. The effects of different multifactor on the mechanical properties and water resistance of SMOCC were systematically investigated using response surface methodology , and relevant polynomial regression models were established and verified. Subsequently, the composition of the hydration products and the SMOCC's micromorphology were investigated using X-ray diffraction and scanning electron microscopy. The results indicated that the strength and water resistance of the SMOCC were affected by single factors as well as the interactions of multi-factor. The optimum contents of MgO/MgCl 2 molar ratio, MgCl 2 solution concentration, and content of NaH 2 PO 4 were 11, 25 %, and 0.5 %, respectively, under which the SMOCC exhibited excellent strengths and water resistance. In addition, the proposed quadratic polynomial models accurately predicted the properties of SMOCC and reflected the effects of multi-factor interaction on the mechanical strength and water resistance of SMOCC.