Chemical stabilization of three Texas Vertisols with sulfonated naphthalene

Abstract

Vertisols shrink and swell with changes in the moisture content of the soil. The volume changes that occur in Vertisols cause destructive forces that can damage a structure built on these soils. This damage is a serious consideration in the management and design of roadways, foundations, and runways. Therefore, there is a need to find solutions to this problem. Condor SS is a stabilization agent that has been marketed with little to no data on its effectiveness. It is marketed as a sulfonated naphthalene "ionizer" that "releases" water from the clays in the soil and reduces shrink/swell. A sulfonated naphthalene standard was tested on three Texas Vertisols to determine its effect on soils with similar mineralogy that represent a range of pH values found in Texas Vertisols. Changes in the mineralogy, in the cation exchange capacity, and in the fabric of the soil were examined to determine how changes may affect the swelling of the three test soils. Tests indicated that a new mineral phase identified as basaluminite, or an intermediate hydroxy aluminum phase, has an effect on the physical characteristics of the soils tested. Basaluminite was evident in the mineralogical analysis of the three soils after treatment. Hydroxy aluminum groups evidently reduced the cation exchange capacity of each of the soil clays. Each soil showed a decrease in permeability and a decrease in swell after treatment with a standard sulfonated naphthalene mixture. Electron microscopy indicated that the interaction of the soil particles was altered due to treatment with the sulfonated naphthalene standard and changed the fabric of the soil due to increased aggregation of particles. This research shows there is a positive effect against the volume changes caused by the shrinking and swelling of Vertisols due to the addition of sulfonated naphthalene to the soil. It also indicates that laboratory testing is essential before adding the stabilizer to the soil because of differences in soil properties.