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.

为探索道路拆除固体废弃物（road demolition solid waste, RSW）资源化利用的有效路径，本研究以RSW为主要原料，辅以水泥作为胶凝材料，探究稻壳生物炭（rice husk biochar, RHB）结合二氧化碳养护改性RSW的可行性。本研究通过直剪试验分析RHB掺量与二氧化碳浓度对RSW抗剪强度的影响，并采用扫描电子显微镜（SEM）、X射线衍射（XRD）与热重试验（TG）表征其微观结构特征与矿物组成。研究结果表明：（1）RSW的抗剪强度随RHB掺量增加先升高后降低，峰值出现在RHB掺量为6%时。养护7d后，掺加6%RHB的RSW试样（RSW6）较未掺RHB的对照试样抗剪强度提升34%~50%。（2）碳化养护可进一步强化RSW的抗剪性能，在二氧化碳浓度为40%时提升效果最佳；在此条件下，RSW6-40试样的抗剪强度较RSW6最高提升39%。（3）碳化养护可显著提升试样黏聚力（最高提升66%），而内摩擦角的提升幅度相对较小（最大为27%）。（4）掺入RHB可促进水化产物与碳化产物的生成，提升试样密实度，进而改善其宏观力学性能。本研究为RSW的资源化高效利用提供了新的思路，并验证了二氧化碳辅助RHB改性技术用于RSW可持续循环利用的技术可行性。
本研究的数据主要以Origin软件绘制的图表形式呈现，包含原始实验数据与可视化图像，可为研究人员共享研究成果提供便利。本研究数据集涵盖稻壳生物炭与二氧化碳养护技术协同改性道路拆除固体废弃物过程中的力学性能与微观结构变化，可为道路拆除固体废弃物资源化利用以及二氧化碳捕集与利用研究提供新的参考视角。