The presence of expansive clays has led to poor performance of flexible pavements, which typically develop significant longitudinal cracks during dry periods. This presentation focuses on the characterization of clay expansiveness (Do we have a problem?) and on innovations using geosynthetics to stabilize roadways (If we have such problem, how do we solve it?).
A novel approach to characterize swelling of clays, involving centrifuge technology, has been recently developed. The procedure involves soil samples subjected to water infiltration during comparatively small testing periods. What makes the centrifuge approach special is that the variable of interest (i.e. the vertical rise) is directly measured. The centrifuge approach is particularly appropriate when using design approaches based on quantification of the Potential Vertical Raise (PVR).
The presentation also includes the results of a comprehensive program conducted to assess the benefits of using geosynthetics to mitigate pavement problems associated with expansive clays. Specifically, stabilization of the pavement base course has been successfully used by the Texas Department of Transportation. The performance property needed to characterize the benefits of geosynthetics for base stabilization was identified. Also, a comprehensive field evaluation was conducted, which involved the construction of test sections with multiple types of geosynthetics, lime treatment, and control sections. The benefits of using geosynthetics were clearly quantified.