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UBC Theses and Dissertations

Bio-composite panels from recycled wood chips for sustainable building applications Ravi, Madhuvandhi

Abstract

Recycling waste materials as replacement for natural resources in building products could help in lowering the environmental impact of the construction industry, provided that their application and processing is properly engineered. Wood waste is one of the chief construction wastes in Canada and many other countries worldwide. In this study, a novel bio-composite panel made with recycled wood chips is presented and assessed. The bio-composite binder was a natural hydrated lime with addition of metakaolin. The inclusion of various additives such as sodium hydroxide, recycled wood ash, and magnesium-rich powder recycled from the cutting waste in the production of magnesium oxide boards, was also explored. The effects of different binder compositions and proportions on the microstructure of the binder, its compatibility with the wood chips, and the engineering properties of the final bio-composite product were investigated. Finally, the effect of different curing conditions is considered, including accelerated carbonation by CO₂ incubation. Following ASTM specifications, 3 replicates of 550 x 550 x 70 mm panels for each bio-composite formulation and curing condition were cast. Specimens were cut from the panel to test the mechanical and thermal properties. Extent of carbonation within the panel was analyzed by standard colouring observation after addition of phenolphthalein and compared with control specimens cured without CO₂ incubation. These analyses were supported by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) of the binders and the bio-composite to monitor the various reactions occurring in the binder, including hydraulic and pozzolanic reactions, carbonation and additional reactions. An optimised binder composition of lime and metakaolin was successfully designed based on the strength data obtained on binder pastes. The bio-composite produced by combining wood chips and the optimised binder possessed good mechanical and thermal properties. While it met the minimum requirements of compressive strength and thermal conductivity as specified by ASTM standards, future work will need to focus on improvement of the flexural behavior. It was also found that carbonation curing of specimens helped in rapid strength gain and improvement of the matrix. Further, microstructure analysis of the bio-composite helped identify and characterise the reaction products that enhanced its properties.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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