A field and 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 stabilization of the shale actually reduced swelling. Chemical reactions between calcium, present in the hydrated lime, and sulfates, which were present in small amounts did not contribute to swell.

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Report Number

KTC-05-01/SPR 270-03-1I

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