Cement-bonded composite boards made from poplar strands

This study was carried out to explore the possibility of making cement-bonded wood composite building products using poplar (Populus deltoides) chopped strands. The experimental design consisted of two treatments namely wood strand and calcium chloride contents. Boards measuring 450 × 450 × 15 mm3 were manufactured using wood/cement ratios of 40:60, 60:40 and 70:30 by weight and 3% and 7% of an accelerator (CaCl2⋅H2O). At least four replications were fabricated for each treatment, and the mechanical properties and water absorption of the boards were evaluated according to DIN 68763. The mechanical properties in terms of modulus of rupture, modulus of elasticity, internal bond and impact strength were investigated and compared to the neat cement controls. Test results showed that addition of CaCl2 tends to enhance both the mechanical and water-resistance of wood–cement composites. The bending and impact strengths of the wood–cement specimens increased with an increase in the wood content, and the maximum values were obtained at wood loading of 60% by weight. The negative influence of wood content on the internal bond can be explained by the reduced bonding ability because of weaker wood strands compared to cement. Water absorption and internal bonding were inversely proportional to the increase of cement mixture ratio, and their values increased proportional to the increase of wood ratio in the mixture. In addition, all properties of the boards were improved when the CaCl2 content was increased from 3% to 7%.

► Wood content had significant effects on the mechanical and sorption properties of the composites.
► Addition of 7% CaCl2 had significant positive effects on mechanical and sorption properties.
► Water absorption and internal bonding were inversely proportional to the increase of cement ratio.