The performance of three pavement designs with expansive clay subgrade is presented. the pavements have been subjected to extensive warping attributed to differential swelling of the underlying soil. the purpose of this paper is to evaluate the effectiveness of the three designs in reducing warping, and to provide suggested alternative designs. the study focuses on pavements west of dallas, texas, situated over weathered shale of the eagle ford geologic formation. theweathered shale is highly expansive with heaving in excess of 12 in. being recorded. postconstruction heave is attributed to increase in the soil moisture regime over time. pavement warp occurs primarilyin deep cut areas where the finished grade lies near or below the original zone at which soil moisture was stable and was not influenced by seasonal fluctuations. data indicate that the overall movement of the pavements studied was upward. differential vertical movementscaused warping. the differential movement is attributed to the influence of (a) underground utilities; (b) micro and macro soil structure features; (c) drainage; (d) patterns of water migration; and (e)stress release. the study evaluates the performance of three specific pavements. subgrade treatments used to minimize potential movements included removal and replacement with lime stabilized soils and inert fills, and maintaining positive drainage. alternative subgrade treatment by preswelling is discussed. modification of pavement shoulders and base to account for shrinkage and loss of bearing support is a necessary component of preswelling design. preswelling and suggested base and shoulder modifications are compared to current designtechniques used in the area on an economical basis. this paper appeared in transportation research record no. 1137, soil mechanics considerations in arid and semiarid areas. for covering abstract see irrd no 817740.
Abstract