Current engineering practice for determining the volume change behavior of unsaturated expansive soils are mostly based on simplified tests, and correlations with index properties. Such practices can lead to uneconomical and distress prone foundation designs. Hence, there is a fundamental research need to review the current characterization practices in expansive soils and to revise them to reflect the current state of knowledge of unsaturated soil mechanics. The research team from both University of Texas-Arlington and Arizona State University are working towards accomplishing this research need by performing various experimental and modeling tasks. Experimental tasks include investigations on eight types of expansive subsoils to determine Soil Water Characteristic Curves (SWCCs) over a wide range of soil suction, measure volumetric swell strain and swell pressure with consideration of clay mineralogy, moisture content, dry unit weight, and stress history. Modeling tasks include development of analytical formulations to predict swell characteristics using SWCC attributes, clay mineralogy, pore void data, and study flow and deformation based finite element modeling to simulate volume change behavior. The final outcome of this research is the development of methods for better predictions of expansive soil properties using unsaturated soil mechanics principles.

The broader impacts of the research will focus on training graduate and undergraduate students in unsaturated soil mechanics and expansive soil characterization; incorporating research findings into undergraduate and graduate courses; strengthening understanding of volume change behavior of expansive soils and providing better characterization tools for design of infrastructure foundations on expansive soils; involving women and minority students in research tasks; and teaching simple experimental modules in summer classes to K-12 students to enhance their interests in civil engineering.