Value-added recycling of construction waste wood into noise and thermal insulating cement-bonded particleboards

Large amounts of waste wood formwork from construction sites end up with landfill disposal every day. This study aims to develop a practicable technology for recycling construction waste wood into formaldehyde-free cement-bonded particleboards that have value-added features of high strength, light weight, and thermal/noise insulation for reuse in building and construction applications. The mineralogy and microstructure of particleboards were characterized by X-ray diffraction, thermogravimetry, and mercury intrusion porosimetry analyses. Among the mineral admixtures, chloride accelerated precipitation of oxychlorides while sulphate produced calcium sulphoaluminate for promoting early strength development. The use of 2% CaCl2 proved to be sufficient for improving the wood-cement compatibility. At wood-to-cement ratio of 3:7 by weight (i.e., 3:1 by volume), cement hydrates in the porous structure ensured acceptable dimensional stability (<2% swelling). By adjusting the water-to-cement ratio to 0.3 and density of the particleboards to 1.54 g cm−3, the volume of capillary pores was effectively reduced from 0.16 mL g−1 to 0.02 mL g−1. The more compact microstructure contributed to high fracture energy at 6.57 N mm−1 and flexural strength of 12.9 MPa. Using the above optimal production conditions, the particleboards complied with the International Standard (9 MPa) while enabling reuse as light-weight structure. The particleboards also manifested outstanding structure-borne noise reduction (at 32–100 Hz) and low thermal conductivity (0.29 W m−1 K−1), suggesting potential application as acoustic and thermal insulating materials. Preliminary cost-benefit analysis illustrated economic viability of the proposed approach. Therefore, technological innovation is crucial for delivering an eco-friendly solution to waste wood recycling for the building and construction industry.