Evaluation of a Clayey Soil Stabilized by Calcium Carbide Residue as Pavement Subgrade

Assessment of resilient modulus property of subgrade soil is prerequisite for design of flexible pavement using mechanistic-empirical approach. Though clayey soils possess good resilient characteristics, they also undergo significant plastic deformation. This necessitates determination of permanent deformation along with resilient modulus to understand the intricate nature of the soil under consideration. Tropical red soils of Indian subcontinent possess good strength characteristics at optimum moisture content; however, excess of moisture decreases the strength of these soils drastically. Utilization of industrial by-products for soil amelioration is one way to make the regional soils meet the requirements of mechanistic-empirical design approach. In addition to this, industrial by-products not only improve the engineering behavior of the soil but also help reduce the landfill area. In the present study, effect of calcium carbide residue (CCR), a by-product of acetylene industry, on static strength and accumulation of permanent strain in red soils is investigated. Natural red soil and CCR-beneficiated red soils are examined under various moisture contents and stress levels for understanding the effect of these variables on permanent strain. Shakedown theory is used to differentiate the stress levels as stable behavior and unstable behavior. Results indicated that the addition of CCR to red soil leads to a significant reduction in the permanent strain. Power law and VTT models are also used in order to check the consistency of experimental data, and results yielded higher coefficient of determination (R2) values indicating the strength of developed models.