Published: Oct 2012
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Stabilization of mechanically and volumetrically unstable clay soils is well supported in the literature, and stabilization of clay soils, and in particular highly plastic clay soils, has been a popular practice for decades. However, the basis for this popularity has largely been construction expediency provided by the physico-chemical changes that occur due to calcium ion saturation of the clay soil lattice and pozzolanic reactions between lime and (primarily) clay minerals and amorphous silicates. A more careful look at the improvement derived by lime stabilization of clay soils in terms of resilient modulus improvements especially at near saturation moisture contents, reduction in the rate of accumulation of plastic strains and the substantial improvements in volumetric stability makes it appropriate to take a closer look at the structural beneficiation of lime stabilization in mechanistic-empirical pavement design. The progression toward a more mechanistic design methodology, i.e., through the American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG), offers an opportunity to define research activities contemporary with MEPDG in order to take full advantage of structural and volumetric stability improvements that can be realized through lime stabilization. A short and directed review of the pertinent literature toward this direction, improvements in mechanical and volumetric stability that can be derived through lime stabilization, and research topics that need to be addressed in order to improve the utility of how lime stabilized layers are addressed in the MEPDG and other mechanistic pavement design approaches are presented.
Little, Dallas N.
Texas A&M Univ., College Station, TX