The mechanical strength, microstructure, and transport properties of steel slag reinforced loess soil system

Steel slag, as an industrial byproduct obtained from the steel manufacturing industry, may cause land occupation, resource waste, and environmental pollution. The application of steel slag as a material for soil reinforcement in road engineering is very popular due to its potential hydration activity. The unconfined compression strength, microstructure, and transport properties of loess soil with cement, lime and steel slag were investigated. The results show that the loess soil can be reinforced by cement, lime, and steel slag to varying degrees. The reinforcement mechanism of cement for loess soil is realized by pore filling by cement hydration products such as CH, C-S-H and AFt, and their unconfined compression strength is improved by reducing the porosity. The reinforcement mechanism of lime for loess soil is achieved by pore filling by hydration products such as CH and CaCO3, and their strength is improved by a refined pore structure where the porosity has not been significantly reduced. The reinforcement mechanism of steel slag for loess soil is a combined mechanism of cement and lime, including pore filling and refined pores. The pore structure of reinforced soil can be studied at different scales by the MIP, LF NMR, and X-CT test methods. The transport properties including diffusivity and permeability of reinforcing soil can be well explored by Avizo software based on the microstructure obtained from X-CT.