Effects of Carbon–Magnesium Reactions on the Physical and Mechanical Properties of Lightweight Carbonated Stabilized Soil

Li Shao, Wangchen Yu, Qinglong You, Suran Wang*, Xi Du,, Bin He, Shichao Tao, Honghui Ding, Chao Bao

1 School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China

2 School of Civil Engineering, Kashi University, Kashi 844000, China

3 School of Transportation, Southeast University, Nanjing 210096, China

摘要

Global urbanization has led to massive generation of high-water-content waste slurry, creating serious environmental challenges. Conventional treatment methods are costly and unsustainable, while cement-based foamed lightweight soils typically exhibit low strength and limited CO2 sequestration. To address this issue, this study proposes a novel stabilization pathway by integrating a MgO–mineral powder–carbide slag composite binder with CO2 foaming–carbonation. The approach enables simultaneous slurry lightweighting, strength enhancement, and CO2 fixation. A series of laboratory tests were conducted to evaluate flowability, density, compressive strength, and deformation characteristics of the carbonated lightweight stabilized slurry. Microstructural analyses, including SEM and XRD, were used to reveal the formation of carbonate phases and pore structures. The results showed that MgO content strongly promoted carbonation, leading to denser microstructures and higher strength, while mineral powder and carbide slag optimized workability and pore stability. Orthogonal testing indicated that a mix with 25% mineral powder, 12.5% MgO, and 7.5% carbide slag achieved the best performance, with unconfined compressive strength up to 0.48 MPa after carbonation. Compared with conventional cement- or GGBS-based foamed lightweight soils, the proposed system exhibits superior strength development, improved pore stability, and enhanced CO2 sequestration potential. These findings demonstrate the feasibility of recycling high-water-content waste slurry into value-added construction materials while contributing to carbon reduction targets. This study not only provides a sustainable solution for waste slurry management but also offers new insights into the integration of CO2 mineralization into geotechnical engineering practice.

主要内容

该研究提出一种以 MgO–矿粉–电石渣复合胶凝体系结合 CO₂ 发泡–碳化 的新型高含水废浆固化方法，实现了废浆轻质化、力学增强与碳固化同步。通过正交试验与 SEM、XRD 分析，确定最优配比为 25% 矿粉 + 12.5% MgO + 7.5% 电石渣，其 28 d 抗压强度达 0.48 MPa、90 d 可达 0.894 MPa，满足隧道回填材料强度要求。微观机理显示 MgO 与 CaO 经水化–碳化反应生成碳酸镁、碳酸钙及 C–S–H 凝胶，填充孔隙并形成致密骨架，从而提高强度与稳定性。该 CO₂ 发泡–碳化复合技术兼具减碳与废浆资源化优势，为绿色地基工程材料提供了可行的新途径。

创新与优势

  1. CO₂发泡–碳化复合法 同时实现：

  • 废浆轻质化；

  • 力学增强；

  • 二氧化碳固化与减排。

  1. 解决传统MgO碳化在高含水体系中泡沫不稳、孔塌陷等问题。

  2. 在低胶结材料用量下获得与水泥基体系相当的强度，且CO₂封存能力更高。

引用格式

Shao L, Yu W, You Q, Wang S, Du X, He B, Tao S, Ding H, Bao C. Effects of Carbon–Magnesium Reactions on the Physical and Mechanical Properties of Lightweight Carbonated Stabilized Soil. Buildings. 2025; 15(19):3571. https://doi.org/10.3390/buildings15193571