Cement boards reinforced with wood sawdust: an option for sustainable construction

Ochroma pyramidale is a fast-growing forest species with low-density wood. The present study had the goal to assess the effect of extractive removal on the performance of the species for producing wood-cement boards (WCB). Wood particles were submitted to three types of treatment for extractives removal: cold water, hot water and sodium hydroxide (NaOH). An entirely randomized design with four treatments was established, respectively, T1-control treatment, T2-cold water, T3-hot water and T4-NaOH, with 4 replicates (boards) per experimental treatment, to assess the effect of extractives removal on the boards' physical and mechanical properties. Wood/cement ratio=1:5, water/cement ratio=1:2 and 4% CaCl2 as additive based on dry mass of cement were used. The following WCB properties were evaluated: density, compaction ratio; water absorption and thickness swelling after 2, 24 and 72 h of water immersion; and mechanical strength during static bending (moduli of elasticity and rupture). The results showed there was no need for wood particle treatment, since no improvement of the boards' physical-mechanical properties was achieved by previous application of cold or hot water or NaOH on the particles. Water absorption and thickness swelling were lower than the levels reported in the literature and minimum values specified by WCB factories. Despite having weaker mechanical properties than those required for structural uses, wood from Ochroma pyramidale can be employed in the production of boards designed for use in moist environments but not having structural importance, such as for partitions, walls, tile flooring and exterior siding.