Effects of Organics on Stabilized Expansive Subgrade Soils

Abstract

Organic soils are the combination of decayed plant matter and weathered rock material. These soils are known for their inferior engineering behavior. In order to get the precise control over the engineering behavior of organic rich soils, they are often stabilized either with lime or cement. However, transportation agencies in the United States reported that these stabilized soils bearing organic content less than 1 percent have never achieved the desired improvement or the improvement disappeared over a period of time. Therefore, a laboratory investigation was initiated to understand the mechanisms when calcium-based additives (lime and/or cement) are amended with organic rich expansive soils. Two soils having high and low organic content were considered for detailed investigation. Firstly, optimum dosage of the stabilizer was determined for the selected soils. The strength of control (untreated) and stabilized soils were determined at different curing periods. In this paper, the influence of organic matter on the engineering behavior of the lime and cement stabilized organic rich soils are discussed in detail.