AN ANALYSIS OF THE MECHANISMS AND EFFICACY OF THREE LIQUID CHEMICAL SOIL STABILIZERS: VOLUME 1

Abstract

Liquid chemical products are marketed by a number of companies for stabilizing pavement base and subgrade soils. If effective, these products could be used as alternatives for treating sulfate-rich soils, which are susceptible to excessive heaving when treated with traditional, calcium-based stabilizers like lime, cement, and fly ash. However, the chemical composition, stabilizing mechanisms, and performance of these liquid products are not well understood. The primary objective of this study was to investigate and identify the mechanisms by which clay soils are modified or altered by these liquid chemical agents. Three representative, commercial products were selected for study: an ionic product, an enzyme product, and a polymer product. The chemical composition of each was characterized using standard 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, the mechanisms of soil modification at the particle level were studied using physical-chemical analyses of untreated and treated soil samples. Very high product application rates were used so that possible soil modifications could be observed. In a paired macro-characterization study, standard geotechnical laboratory tests were performed 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. The findings of this study clearly point to the need to conduct standard laboratory tests, prior to specifying the use of these products in field applications, to prove the effectiveness of the treatment on a particular soil type at a given chemical application rate.