Recent research has shown that the subgrade soil type and its engineering properties govern the performance of the pavement, especially for clayey soils. However, current application of the Pavement_ME in Indiana does not fully account for the changes of type of soil and stiffness that may arise with treatment. This research addresses this issue by exploring engineering properties, namely fines content, plasticity index, unconfined compression strength and resilient modulus of subgrade stabilization alternatives. The effects of changes in moisture content and temperature on the stiffness of treated subgrades are also studied. Three A-7-6 soils and one A-6 soil mixed with lime kiln dust (LKD) and/or Portland cement (PC); and one A-7-6 soil mixed with quick lime (QL) are investigated. An increase in the soils grain size and a decrease in the plasticity is observed with all chemical treatments; however, the change in soil type is only evident when the optimum amount of treatment is doubled. An increase in the soil’s stiffness is always seen for treated soils, in some cases by a factor of two. Test conditions are investigated to develop new appropriate protocols that represent field conditions for changes in moisture and temperature. The MR results show that the action of wetting-drying and freezing-thawing cycles reduces the stiffness of the treated soils, at optimum treatment, down to values similar to, or lower than, those of the untreated soils. When the amount of chemical is doubled, the treated soils’ MR improves over that of the untreated soils, even after the wetting-drying cycles.

Report Number



resilient modulus, subgrade, freezing-thawing, wetting-drying, clayey soils, chemical treatment, overdosing, pavement

SPR Number


Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, Indiana

Date of this Version