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Mechanical, durability and environmental aspects of magnesium oxychloride cement boards incorporating waste wood

He, Pingping, Hossain, Md. Uzzal, Poon, Chi Sun, Tsang, Daniel C.W.
Journal of cleaner production 2019 v.207 pp. 391-399
cement, durability, environmental impact, fiber content, fly ash, greenhouse gases, humans, modulus of rupture, particleboards, plywood, sludge ash, system boundary, temperature, thermal conductivity, toxicity, waste wood, wastes, water uptake, wood, wood fibers
Waste timber formwork from construction sites was used as fibre to prepare wood-magnesium oxychloride cement (MOC) board. The effect of wood fibre content, pulverized fly ash (PFA) and incinerated sewage sludge ash (ISSA) on the mechanical and durability properties of wood-MOC board was investigated. Greenhouse gases (GHGs) emission, one of the representative and most globally concerned environmental impacts, for the production of different types of composite boards was assessed and compared by using lifecycle assessment (LCA) technique. The ‘cradle-to-gate’ system boundary with 1 kg of board production was considered as the functional unit in this assessment. The result showed that the wood-MOC composites prepared with a higher content of wood fibre had a lower thermal conductivity, higher flexural strength, higher residual flexural strength after exposure to high temperatures and water immersion, and better noise reduction effect. Even though the water absorption was increased with the increase of wood fibre content, it can still be considered to be low. The wood -MOC composites incorporating ISSA showed higher flexural strength, better high temperature resistance and better water resistance than other composites. In addition, the production of the wood MOC board induces lower GHGs emission than plywood and lower human toxicity than conventional resin-based particleboard.