Seasonal freezing and thawing significantly affect the bearing capacity of weaker low-volume roads. The length of time and the degree of thaw weakening depends mainly on the properties of the roadway layers, degree of saturation, density, and temperature. A research project was carried out by the University of Manitoba to find the relationship among these factors, and to provide a reasonable prediction of the performance of thaw-weakened roads during the spring in Manitoba. The study was conducted on two pavement sections, a thin asphalt pavement and a thin asphalt-surface-treated road. Instrumentation, including water content reflectometer probes, thermistor probes, and a mini weather station, were successfully tested in the laboratory and then installed at test sites. Reference temperature based thawing index and N-factor based thawing index were examined to determine whether they would accurately predict the start date of spring load restriction. The prediction was validated by measured moisture content and thawing depth at test sites. The results indicated that these two thawing indices were sufficiently accurate for predicting the start date of spring load restriction in Manitoba environment.
展开▼
