Characteristics and engineering properties of the soft soil layer at the top of highway subgrades.

PDFTech ReportKTC-05-01SPR270-03-11KY SPR-03-270SwellingCalcium hydroxideSubgrade (Pavements)Laboratory testsShaleClay soilsChemical reactionsCalciumSulfatesKentuckyUniversity of Kentucky Transportation CenterBeckham, Tony L.Hopkins, Tommy C.University of Kentucky Transportation CenterKentucky. Transportation CabinetUnited States. Federal Highway AdministrationUS Transportation CollectionA field laboratory investigation was performed to determine why excessive swelling was occurring on a pavement section of KY Route 499 that was about four years old. Swelling occurred on a section of roadway that had been constructed with a hydrated lime-stabilized subgrade. As shown by laboratory swell tests, swelling of the pavement was due to the absorption of water and expansion of the compacted clay shale subgrade. Results of laboratory swell tests showed that the hydrated lime, and sulfates, which were present in small amounts did not contribute to swell