Comparison of Springtime Modulus Values for Cement-Treated and Untreated Pavement Base Layers in Northern Utah

The objective of this research was to compare the stiffness of cement-treated base (CTB) layers and untreated base course (UTBC) layers in a cold region during the spring season. The scope of work included testing of three pavement segments comprising CTB layers and two comparable pavement segments comprising UTBC layers in northern Utah. Nondestructive testing using a portable falling-weight deflectometer was performed to evaluate the stiffness of the base layer at four test locations within each pavement segment during May 2024. The average modulus values for the CTB and UTBC layers were computed to be 708 MPa (102 ksi) and 259 MPa (38 ksi), respectively. Therefore, in this field study directly comparing pavement structures comprising CTB layers and UTBC layers of similar design thicknesses and subgrade types, the springtime stiffness of the CTB layers was observed to be approximately 173 percent greater, on average, than the corresponding stiffness of the UTBC layers.