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 lightweight 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. (C) 2016 Elsevier Ltd. All rights reserved.