Lightweight cement composites containing end-of-life treated wood – Leaching, hydration and mechanical tests

Abstract

A huge amount of treated wood waste containing hazardous substances is produced every year all over Europe that simply ends up in landfills. In this study, the authors investigate the practical feasibility of using end-of-life treated wood for producing innovative lightweight cement composites. For this purpose, wood waste from four different sources was characterised to assess the presence of leaching substances and to ascertain physical properties relevant to the production of cement composites. Afterwards, cement pastes containing, firstly, wood extractives, and later, wood particles were prepared to assess the compatibility between the wood and Portland cement binder. To improve the wood-cement compatibility, additional tests were carried out using extracted and chemically treated wood particles. The results were discussed in terms of hydration heat and mechanical properties. Finally, a concrete mix containing selected wood particles was produced for a preliminary examination of the effect of wood waste on the mechanical properties of a reference concrete. The results show that the concentration of leaching substances can vary significantly depending on the source of wood waste. Small variations were found in the hydration heat profile of different cement composites containing up to 10 %(w/w) of wood particles, contrasting with the significant reduction found in compressive strength. The results of the concrete mixes further show that the incorporation of wood particles significantly reduces the mechanical performance of the hardened material, though such composites can still be used in applications with low-structural requirements.