Thermal Activity of Base Course Material Related to Pavement Cracking.

摘要

An initial computer study using a heat transfer program showed that freeze-thaw activity during a winter,for Perryton,Texas,was centered mainly in the base course for a typical pavement. Comprehensive freeze-thaw testing showed the base course to be more active,thermally,than asphaltic concrete. The thermal activity is composed of a freeze deformation and a residual deformation. Both quantities are related to the soil moisture suction of the material. The soil moisture suction which develops in a sample is a function of the grain size,moisture,pore structure and clay mineralogy. Clay mineralogy determinations were done using x-ray diffraction to obtain the relative percentages of the clay minerals present. A direct relationship is established between the freeze deformation and clay mineralogy of the material tested. The data also demonstrate the validity of using clay mineralogy properties as a design quantity for base course material.