Qiao Wei, Dai Kuncheng, Lin Daming, Yue Bing, Su Bidi, Lin Zhiping, Chen Mingyou, Zheng Haofeng, Luo Zhihua
School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China.
Research Institute of Highway Ministry of Transport, Beijing 100088, China.
Materials (Basel). 2025 May 20;18(10):2377. doi: 10.3390/ma18102377.
Lateritic clay is widely distributed in southern China, and its strength is greatly affected by water content. The elevated moisture content in lateritic clay during monsoon periods frequently results in insufficient shear strength for standard engineering applications. Large quantities of solid waste, including steel slag, fly ash, and granulated blast furnace slag, are produced as industrial by-products. This paper is based on the backfilling resource utilization of steel slag, fly ash, and ground-granulated blast-furnace slag as lateritic clay improvement admixtures, along with the stress-strain behavior, strength characteristics, and microstructure of steel-slag-modified lateritic clay, fly-ash-modified lateritic clay, and ground-granulated blast-furnace slag-modified lateritic clay, by combining uniaxial compression tests, straight shear tests, and scanning electron microscopy observation. The experimental results were analyzed to determine the appropriate dosages of three kinds of solid waste and their mechanisms in lateritic clay modification. The results indicate that the unconfined compressive strength of SS-modified lateritic clay exhibited an increase with an increase in SS dosage in the range of 1-7%, the unconfined compressive strength of FA-modified lateritic clay showed an increase with an increase in FA dosage in the range of 1-5%, and the unconfined compressive strength of GGBFS-modified lateritic clay increased with an increase in the use of GGBFS in the range of 1-5%. Under the condition of a 7-day curing age, the unconfined compressive strength of lateritic clay modified with 7% SS increased by approximately 397%, while that modified with 5% FA and 5% GGBFS exhibited increases of about 187% and 185%, respectively. The stress-strain relationship of fly-ash and blast-furnace slag-modified lateritic clays showed elastic-plastic deformation. But the stress-strain behavior of steel-slag-modified lateritic clay at a steel slag dose greater than 5% and a maintenance age greater than 7 days showed elastic deformation. Analyzing the SEM images shows that the more hydration products are generated, the relatively higher the unconfined compressive strength of modified lateritic clay is, and the form of deformation of modified lateritic clay is closer to elastic deformation. Through comparative analysis of modified lateritic clay samples, this study elucidates the property-altering mechanisms of waste powder additives, guiding their engineering utilization.
红土在华南地区分布广泛，其强度受含水量影响较大。季风期红土中含水量升高，常常导致其抗剪强度不足以满足标准工程应用的要求。包括钢渣、粉煤灰和粒化高炉矿渣在内的大量固体废物作为工业副产品产生。本文基于钢渣、粉煤灰和粒化高炉矿渣作为红土改良剂的回填资源利用，结合单轴压缩试验、直剪试验和扫描电子显微镜观察，研究了钢渣改良红土、粉煤灰改良红土和粒化高炉矿渣改良红土的应力 - 应变行为、强度特性及微观结构。分析实验结果以确定三种固体废物的合适掺量及其改良红土的作用机制。结果表明，钢渣掺量在1% - 7%范围内，钢渣改良红土的无侧限抗压强度随钢渣掺量的增加而增大；粉煤灰掺量在1% - 5%范围内，粉煤灰改良红土的无侧限抗压强度随粉煤灰掺量的增加而增大；粒化高炉矿渣掺量在1% - 5%范围内，粒化高炉矿渣改良红土的无侧限抗压强度随粒化高炉矿渣用量的增加而增大。在养护龄期为7天的条件下，7%钢渣改良红土的无侧限抗压强度提高了约397%，而5%粉煤灰和5%粒化高炉矿渣改良红土的无侧限抗压强度分别提高了约187%和185%。粉煤灰和高炉矿渣改良红土的应力 - 应变关系呈现弹塑性变形。但钢渣掺量大于5%且养护龄期大于7天时，钢渣改良红土的应力 - 应变行为呈现弹性变形。分析扫描电子显微镜图像表明，生成的水化产物越多，改良红土的无侧限抗压强度相对越高，且改良红土的变形形式越接近弹性变形。通过对改良红土样品的对比分析，本研究阐明了废粉添加剂的性能改变机制，为其工程应用提供了指导。
