An Experimental Study on the Use of Foam Mortar to Improve the Bearing Capacity of Soft Soil
Keywords:
Bearing Capacity, Foamed Mortar, Shear Strength, Soft Clay, Soil.Abstract
Soft clay soils generally exhibit low bearing capacity, high plasticity, and limited shear resistance, making stabilization necessary for construction applications. This study investigates the effect of foamed mortar addition at 0%, 15%, 20%, and 25% on the physical and mechanical properties of soft clay obtained from Semarang City, Indonesia. The research employed a quantitative experimental approach through laboratory testing, including grain-size analysis, Atterberg limits, direct shear testing, Standard Proctor compaction, and laboratory California Bearing Ratio (CBR). The untreated soil was dominated by clay-sized particles at 89.88% and exhibited a specific gravity of 2.487, liquid limit of 53.21%, plastic limit of 29.82%, and plasticity index of 23.39%. The untreated soil also showed an internal friction angle of 11.06°, optimum moisture content of 34.00%, maximum dry density of 1.27 g/cm³, and unsoaked CBR of 5.10%. Increasing the foamed mortar content substantially modified the grain-size composition and improved the mechanical performance of the soil. At 25% foamed mortar content, the internal friction angle increased to approximately 34.50°, while the maximum unsoaked CBR increased to 25.70%, approximately 5.04 times the untreated value. The findings demonstrate that foamed mortar is effective in improving the shear resistance and bearing capacity of soft clay, with the 25% mixture providing the highest documented mechanical performance.
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