The Effects of Lime and Cement Addition on the Compaction and Shear Strength Parameters of Silty Soils

This article presents the results of laboratory tests of compaction parameters and shear strength of silty soils with and without the addition of hydraulic binder in the form of lime and/or cement. The tests were carried out on samples formed with an optimum moisture content and with 0, 3, 5, and 8% hydraulic binder added to the dry mass of the soil. The soil samples were examined after 7 and 14 days of air-water treatment without and with freeze-thaw cycles. It was found that the addition of lime and cement caused changes in the compaction parameters. This effect depended to a large extent on the type of binder, and also on the grain size composition of the tested soil. The tests showed that the shear strength and the parameters describing it, i.e., the angle of internal friction and cohesion, were high and largely depended on the type of binder and the sample treatment method, as well as its duration. The obtained results indicate that the use of hydraulic binders was an effective method of surface stabilization. Improving soil properties based on the addition of a hydraulic binder is a beneficial method for the environment from the viewpoint of sustainable development and reducing CO₂ emissions because it does not require the use of, e.g., soil replacement. Using the SHAP algorithm, it was found that normal stress, initial moisture content, and curing time of the samples were the main input features that influenced the shear strength.