Addressing Clay Mineralogy Effects on Performance of Chemically Stabilized Expansive Soils Subjected to Seasonal Wetting and Drying

Premature failures in chemically stabilized expansive soils cost millions of dollars in maintenance and repair. One reason for these failures is the inability of existing stabilization design guidelines to take into account the complex interactions between the clay minerals and the stabilizers. It is vital to understand these complex interactions, as they are responsible for the improved strength and reduction of swelling/shrinking in these soils, which in turn affects the overall health of the infrastructure. This research study examined the longevity of chemically stabilized expansive soils subjected to wetting/drying conditions, with a major focus on clay mineralogy. Eight different natural soils with varying clay mineralogy were subjected to wetting/drying durability studies after they were stabilized with chemical additives including quicklime and cement. Performance indicators such as volumetric strain and unconfined compressive strength trends were monitored at regular intervals during the wetting/drying process. It was observed that clayey soils dominant in the mineral montmorillonite were susceptible to premature failures. It was also noted that soils dominant in other clay minerals exhibited early failures at lower additive contents. For the first time, an attempt was made to address the field implications of the laboratory studies by developing a correlation that predicts service life in the field based on clay mineralogy and stabilizer dosage.