Evaluation of Nontraditional Soil and Aggregate Stabilizers: A Summary

EVALUATION OF NONTRADITIONAL SOIL AND AGGREGATE STABILIZERS: A SUMMARY Introduction Proprietary chemical products are marketed by a number of companies for stabilizing pavement base and subgrade soils. Usually supplied as concentrated liquids, these products are diluted in water on the project site and sprayed on the soil to be treated prior to mixing and compaction. If effective, these products might be used as alternatives for treating sulfate-rich soils, which are susceptible to excessive heaving when treated with traditional, calcium-based stabilizers such as lime, cement, and fly ash. However, the chemical composition, stabilizing mechanisms, and performance of these liquid products are not well understood. In this study, we investigated the mechanisms by which clay soils are modified by these liquid chemical agents. We also attempted to quantify changes in the engineering properties of different clays following treatment. We selected three representative commercial products for study: an ionic product, an enzyme product, and a polymer product. The chemical composition of each was characterized using a variety of chemical test methods. The three products were then reacted with three reference clays (kaolinite, illite, and montmorillonite) and several native Texas soils. In the “micro-characterization” study, we studied the mechanisms of soil modification at the particle level using physical-chemical analyses of untreated and treated soil samples. Extremely high product application rates were used so that possible soil modifications could be observed. In a paired “macro-characterization” study, we performed standard geotechnical laboratory tests on untreated and treated compacted soil specimens. The products were mixed at the suppliers’ recommended application rates and at ten times the recommended application rates. These tests failed to show significant, consistent changes in the engineering properties of the test soils following treatment with the three selected products at the application rates used.