A comparative study of red brick powder and lime as soft soil stabilizer

Background: The role of soil in building construction is to support the loads above it. Different types of soil with poor mechanical properties require more attention. Therefore, more effort is needed to stabilize the soil by improving its properties. These improvements are intended to modify soil properties to improve engineering performance, such as strength, decrease in compressibility and permeability. This study aimed to compare the potential of lime and brick powder as stabilizers based on the California Bearing Ratio (CBR) values. Soil stabilization can be defined as modifying the soil properties by chemical or physical means to improve its engineering efficiency. The main objectives of stabilizing soil are increasing its bearing capacity, resistance to weathering processes, and permeability. Methods: This work did laboratory tests with disturbed and undisturbed soil samples. The proportions of lime or red brick powder additives are 0%, 5%, 10%, and 15% of the soil sample. From the results of the laboratory tests, the soil type obtained is MH (low plasticity silt) as per the Unified Soil Classification System (USCS). Results: This study showed that soft soil could be improved by adding lime and red brick powder as a soil stabilizer. In both soaked and unsoaked CBR tests, there was an increase in the CBR value for each proportion of the mixed additives. However, the red brick powder addition (15%) has significantly increased the CBR value. Conclusions: The soil sample mixed with 15% red brick powder had the highest Maximum Dry Density (MDD), about 5.5% over untreated soil. The increment of lime to 15% has increased the CBR soaked by 61% in relation to untreated soil. The increment of red brick powder to 15% has increased the CBR unsoaked by 73% in relation to untreated soil.