Amy Frost !!TOP!!
Frost heave is a primary mechanism of pavement distress in cold regions. The distress exhibited is dependent on the frost susceptibility of the soil within the depth of frost penetration, the availability of subsurface water, and the duration of freezing surface temperatures. Cement stabilization is one technique used to mitigate the effects of frost heave. The tube suction test (TST) is one possible method for determining the frost susceptibility of soils in the laboratory. The purpose of this research was to assess the utility of the TST for identifying non-frost-susceptible (NFS) materials stabilized with cement. This research investigated two aggregate base materials from Alaska that have exhibited negligible frost susceptibility in the field. The unconfined compressive strength (UCS), final dielectric value in the TST, and frost heave at three levels of cement treatment and in the untreated condition were evaluated for both materials. The data collected in this research indicate that, for the two known NFS materials included in this study, the TST is a good indicator of frost heave behavior. The total heave of the untreated materials was approximately 0.15 in. at the conclusion of the 10-day freezing period, which classifies these materials as NFS according to the U.S Army Corp of Engineers. Both materials had final dielectric values of less than 10 in the TST, indicating a superior moisture susceptibility rating. The results of this research suggest that the TST should be considered for identifying NFS materials, including those stabilized with cement. Additional testing should be performed on known NFS materials stabilized with cement and other additives to further assess the validity of using the TST to differentiate between frost-susceptible and NFS materials. Consistent with previous studies, this research indicates that, once a sufficient amount of cement has been added to significantly reduce frost heave, additional cement has only a marginal effect on further reduction. Therefore, to avoid unnecessary expense in construction, the minimum cement content required for preventing frost heave should be identified through laboratory testing and specified by the engineer. In this work, UCS values ranging between 200 psi and 400 psi after a 7-day cure were typically associated with this minimum cement content. Because the scope of this research is limited to two aggregate base materials, further testing is also necessary to validate this finding.