The effect of water-leaching treatment of bagasse and additive content on the properties of cement-bonded particleboard

Background and objectives: As renewable resources, agricultural wastes, such as bagasse, can be used as the raw materials for making cement-bonded particleboard (CBPB). Also for improving cement-bonded particleboard properties by increasing the hydration speed, methods such as water leaching and additives must be examined and used to eliminate or mitigate the effect of harmful substances and to increase the compatibility between organic material and cement. So, the present research is aimed at studying the effect of water-leaching treatment of bagasse and MgCl2 additive content on the properties of cement-bonded particleboard. According to many researchers, thermal treatment of wood creates dimensional stability, reduces the fibers' hydrophilicity and increases the strength of the boards by removing the negative effects of water soluble carbohydrates, hemicellulose and lignin on the hydration speed. Also according to the researches done by some researchers, adding catalysts to water and cement mixture can increase the hydration speed of the cement paste, and the compatibility between wood and lignocellulosic materials and cement is improved and cement hydration process is accelerated. In their research on the hydration speed of six wood species, it was showed that as hydration catalysts, MgCl2 and CaCl2 increase the speed of the process and improve the cement's curing time.
Materials and methods: Materials used in this research include bagasse, Portland cement type II and MgCl2 additive. In this research, using Response Surface Methodology (RSM), the effect of water-leaching treatment and MgCl2 additive content on modulus of rupture (MOR), internal bonding (IB) strength, water absorption (WA) and thickness swelling (TS) of bagasse-based CBPB was examined. Quadratic models were developed to correlate the variables including water-leaching treatment (X1) and additive content (X2) to the dependent variables MOR, IB, WA and TS based on Central Composite Face design (CCF).
Findings: Analysis of variance (ANOVA) showed that hot water-leaching treatment improves the physical and mechanical properties more. Also, optimal condition for improving physical and mechanical properties using hot water-leaching treatment is to use 4.5% MgCl2 additive. In this condition, MOR, IB, WA and TS were 9 N/mm2, 0.3 N/mm2, 17.68% and 1.6%, respectively.
Conclusions: Due to its significance in the statistical analysis, the model presented by Response Surface Methodology provided a suitable and significant estimate to determine the application of the variables. According to the statistical analysis, the effect of water-leaching treatment and additive content on the physical and mechanical properties was significant at the level of confidence 99%.