DESIGN CONSIDERATIONS AND ECONOMIC IMPACTS OF NEAR FREEZING SOIL TEMPERATURES ON SOIL COMPACTION

Soils are an important component of any transportation structure. To improve the engineering properties of these soils, compaction requirements are included in virtually all transportation construction specifications. Field observations indicate however, that soils at near-freezing temperatures may require more compactive effort than soils at higher temperatures. This research project was proposed and conducted to verify the phenomenon's existence, to quantify the resulting economic impact on the cost of soil compaction, and to determine the need for more in-depth research as related to highway design procedures. A series of compaction tests were performed on a temperature-controlled, A-2-4 (0) (AASHTO Designation M-145) soil sample. Research results indicated that, while additional compactive effort is in fact required, it is not significant when compared to the 95% or less of maximum dry unit weight commonly specified for construction. Further compaction tests with a finer grained soil (preferably an AASHTO A-6 or A-7 classification) were indicated.