Reduction of Sulfate Swell in Expansive Clay Subgrades in the Dallas District(Revised)

摘要

The addition of hydrated lime to clay soils is one of the most common methods ofsoil stabilization. However, when sulfates are present in the soil, the calcium in the lime reacts with the sulfates to form ettringite, an expandable mineral. The expansion causes a considerable amount of economical as well as structural problems. Sulfate related heave has been experienced along IH 45 and FM 1382. In this research, a field test method was developed to locate sulfate bearing soils. A permittivity probe was used to measure the electrical conductivity of the in situ soil. The electrical conductivity was then related to sulfate content in soils. The use of low calcium fly-ashes were investigated and proposed as an alternative form of stabilizer for sulfate bearing soils.