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It is known that there is a correlation between hydration heat and physico-mechanical properties of wood based cement panels. Cement hydration is affected by many variables, such as chemical composition, water/cement ratio, wood/cement ratio, wood chemical properties, mineral additions and producing conditions. This study mainly aimed to investigate the effects of press temperature on some properties of three-layer cement bonded particleboard made from the particles of spruce (Picea orientalis) and poplar (Populus tremula). For this purpose, a total of 16 experimental board groups with 1200 kg/m³ target density and 1/3 wood-cement ratio were produced at the press temperatures of (20, 30, 40, 50, 60, 70 and 80) °C. As cement curing accelerator, CaCl2 was used at a rate of 5 % (cement weight basis). The physical, mechanical and thermal properties of the boards were determined. The results indicated that the press temperature substantially affected the properties of cement-bonded particleboard depending on the wood species. In the light of this study, the optimum temperatures in producing of cement-bonded particleboard were found as 40 °C for poplar wood and 60 °C for spruce wood. [ABSTRACT FROM AUTHOR]

Silica fume, which is a highly reactive pozzolanic byproduct of producing silicon metal or ferrosilicon alloys, is known to improve both the mechanical characteristics and durability of concrete. This study investigates the effect of using silica fume as cement replacement materials on some properties of cement bonded particleboard from Douglas fir woods [Abies mordmanniana (Stev.) Spach. Subsp. Nordmanniana]. For this purpose, the three-layer cement bonded particleboards [CBPBs] with 1200kg/m³ target density and 1/2 - 1/3 wood-cement ratios were produced by replacing cement with different percentages of silica fume (10, 15, 20%). As cement curing accelerator, CaCl2 was used at 5% ratio (based on cement weight) for all the boards. The CBPBs produced were tested, according to the related EN Standards, to determine their mechanical and physical properties including modulus of rupture, modules of elasticity, internal bond strength, screw withdrawal strength, density, moisture content, water absorption and thickness swelling. The modulus of rupture values ranged from 9 MPa to 13.6MPa, while the modulus of elasticity values ranged from 5000MPa to 6500MPa. The internal bond strength values ranged from 1.05MPa to 1.95MPa. It was recorded that silica fume performed the improvements up to 20% at modulus of rupture and up to 40% at internal bond strength of the CBPBs. The mechanical properties of all the board types were over the requirements by EN 634-2 standard. Silica fume provided an improvement up to 50% at the thickness swelling values of the CBPBs. The results demonstrated that silica fume had a significant effect on the properties of CBPBs. [ABSTRACT FROM AUTHOR]