Problem definition and objectives: The primary challenge in manufacturing wood-cement composites is the chemical incompatibility between wood and cement, which reduces the setting time and hardening of the cement and disrupts the cement hydration process. The goal of this study was to employ special pozzolanic cement to mitigate the incompatibility between wood and cement, improve cement hydration performance, and enhance the physical and mechanical properties of wood-cement composites.
Methodology: Pistachio wood particles (with thicknesses ranging from 0.3 to 4 mm and lengths from 0.3 to 16 mm), Portland cement type 1-425, and special pozzolanic cement were sourced from Neopan Factory in Rafsanjan and Kerman Cement, respectively. The variable factors included different ratios of special pozzolanic cement to pistachio branch wood particles (50:50, 60:40, and 70:30) and varying concentrations of calcium chloride (3% and 5%). To compare the effects of special pozzolanic Portland cement with standard Portland cement type 1-425, a control treatment was established using type 1-425 Portland cement and pistachio wood particles in a 60:40 ratio with 5% calcium chloride. The Vicat test, mechanical tests for flexural strength and elastic modulus, and physical tests for water absorption and thickness swelling at 2 and 24 hours were conducted to assess the properties of wood cement composite in accordance with international standard protocols.
Results: The results of the Vicat test indicated that type 1-425 cement sets faster than special pozzolanic cement. Additionally, increasing the amount of calcium chloride and adding wood particles to the wood-cement mixture reduced both the setting time and the depth of Vicat needle penetration. The findings further demonstrated that under similar conditions (60% cement, 40% pistachio wood particles, and 5% calcium chloride), special pozzolanic Portland cement significantly outperformed type 1-425 Portland cement in enhancing the physical and mechanical properties of wood-cement boards. This led to increases in flexural strength and elastic modulus by 54% and 11%, respectively, while reducing water absorption and thickness swelling at 2 and 24 hours by 6%, 13%, 31%, and 26%, respectively. Furthermore, samples made with 60% type 1-425 cement and 40% wood particles exhibited higher water absorption and thickness swelling compared to those made with special pozzolanic cement under similar conditions after 2 and 24 hours of immersion in water.
Conclusion: The findings indicated that wood-cement produced with special pozzolanic cement exhibited superior physical and mechanical properties compared to that made with type 1-425 Portland cement. Due to its lighter weight relative to concrete, this composite can be effectively utilized in prefabricated structures, including non-load-bearing walls, partitions, internal building coverings, fire-resistant doors, and sound insulation.