Investigation of local degradation in wood stands and its effect on cement wood composites

Wood-wool cement boards (WWCB) are a type of cement/fibre composite using wood strands as reinforcement. When lignocellulosic materials such as wood are mixed with cement, polysaccharides can leach out and negatively affect the cement hydration. Thus, the WWCB industry has to face those problems, which can cause significant problems during the manufacturing process. This study aims to identify the parameters that can influence the quality of wood and thus the WWCB. The investigation focuses on the potential differences between these two wood samples, by analysing the cement/wood compatibility, the mechanical properties of the wood strands, the microstructure and the chemical composition of the leachates. Two similar spruce wood samples, which have been grown and harvested under the same conditions are compared to each other. When mixed with cement, one sample performed up to expectation in WWCB whereas the second one shows chemical and mechanical problems, resulting in weak WWCBs that cannot fulfil the standards. A comparison two wood samples shows not only different properties of WWCB. Cement-fibre compatibility for one of the sample is below the limit to be used in composite and tensile strength shows a similar behaviour.