CO2-assisted modification of road demolition solid waste with rice husk biochar: shear properties and microscopic mechanism-Yiming Jiang

To explore an effective approach for resource utilization of road demolition solid waste (RSW), this study utilized RSW as the primary raw material and incorporates cement as the cementitious material to investigate the feasibility of modifying RSW using rice husk biochar (RHB) in combination with with CO2 curing. The direct shear tests were conducted to evaluate the effects of RHB content and CO2 concentration on the shear strength of RSW, while the SEM, XRD and TG tests were employed to analyze the microstructure characteristics and mineral composition. The results indicate that: (1) Shear strength initially increases and then decreases with increasing RHB content, with the peak at 6% RHB. After 7 days of curing, the shear strength of RSW6 improved by 34%~50% compared with the sample without RHB. (2) Carbonation curing further enhances the shear performance of RSW, with optimal improvement observed at 40% CO2 concentration. Under these conditions, the shear strength of RSW6-40 increased by up to 39% relative to RSW6. (3) Carbonation curing significantly improves the cohesion (up to 66% increase), while the internal friction angle shows a more modest increase (max 27%). (4) The incorporation of RHB promotes the formation of hydration and carbonation products, enhances sample density, thereby improving its macroscopic properties. This study provides new insights into resource-efficient utilization of RSW and validates the technical feasibility of CO2-assisted RHB modification for sustainable RSW recycling.
The data of this study are mainly presented in the form of graphs plotted by ORIGIN software, including raw data and visual images, which provides a convenient way for researchers to share the research results. The research data mainly include the changes in mechanical properties and microstructure of road demolition solid waste modified by the synergistic effect of rice husk biochar and CO₂ curing technology, which can provide new insights into the resource utilization of road demolition solid waste and the capture and utilization of CO₂.