Recycling contaminated wood into eco-friendly particleboard using green cement and carbon dioxide curing

Landfill disposal of contaminated wood formwork from construction sites presents significant environmental burdens and economic wastage. This study proposed an innovative and low-carbon technology by using magnesia cement and CO2 curing to transform contaminated wood waste into eco-friendly cement-bonded particleboards, which demonstrated excellent compatibility and value-added properties. The microstructure characteristics and cement hydration chemistry were revealed by mercury intrusion porosimetry and X-ray diffraction analyses. At the optimal water to cement ratio of 0.3, the particleboards contained the lowest total pore area (10.2 m2 g−1) and porosity (26.1%), thereby successfully complying with the International Standards of mechanical strength (>9 MPa) and dimensional stability (<2% swelling after 24-h water immersion). An integration of 2-h CO2 curing facilitated carbonation at early stage and reduced the volume of mesopores and air pores, which contributed to strength development and carbon sequestration in the particleboards (8.78% by weight) helping to combat global warming. A subsequent 7-d air curing further enhanced the strength to outcompete those of 28-d air curing only, because rehydrated formation filled in capillary pores (reduced from 0.11 mL g−1 to 0.03 mL g−1). Moreover, fire resistance and thermal stability were improved by the chemistry of magnesia cement and accelerated carbonation. The carbonated particleboards retained high strength and stable dimension after 1-h heating up to 200 °C.