Engineering Behaviour of Cement-Treated Expansive Subgrade Soils from Awgu, Southeastern Nigeria

Abstract

Engineering behaviour of cement-treated expansive soils refers to changes in the engineering properties of the soil in terms of reduction in values of swelling indicators and increase in values of strength characteristics of the soil when it is treated with various percentages of cement. In this study, engineering properties including liquid limit, plasticity index, linear shrinkage, maximum dry density/optimum moisture content, and California Bearing Ration (CBR) of expansive subgrade soils from Awgu, Southeastern Nigeria, were determined in the laboratory and their behaviour in terms of changes in the engineering properties on treatment with various percentages of cement (2,4,6,8 and 10) investigated. Results of the study show that liquid limit, plasticity index and linear shrinkage values of the treated soil were reduced while the maximum dry density and CBR values were increased. The maximum reduction percentages of 34.61% (56.60 to 37.01%), 72.89% (33.60 to 9.11%) and 46.51% (12.90 to 6.90%) in liquid limit, plasticity index and linear shrinkage, respectively; and maximum percent increase of 7.59% (1.58 to 1.70mg/m³, on maximum dry density), 236.36% (11 to 37%, on unsoaked CBR) and 800.00% (3 to 27%, on soaked CBR), were obtained on treatment of the soil with 8% cement by weight. The swelling indicators/parameters of the studied soil are liquid limit; plasticity index and linear shrinkage while the strength characteristics/parameters of the studied soil are maximum dry density and California Bearing Ratio (CBR). Treatment of the soil with cement has thus reduced its swelling potential from high to low and increased the strength significantly

Keywords: Subgrade, expansive soils, cement treatment, plasticity characteristics, reduction percentage, strength characteristics, percent increase.