SEASONAL NONDESTRUCTIVE EVALUATION OF FROST-HEAVE PREVENTION LAYERS IN ASPHALT PAVEMENTS

In cold and snowy regions, road pavements are greatly affected by frost heaving in the ground. The frost heave damages the ground in two ways. The first is because of the frost heaving itself, and the second is because of the decrease in the bearing capacity on the subgrade soil and the subbase courses during spring thaw. A number of methods are available to protect pavement from frost-heave damages. The most popular method used in Japan is the replacement of frost-susceptible soil with local materials such as sand, volcanic ash, and unscreened gravel. In the investigations, the bearing coefficients of the materials generally used in cold regions for subgrade, frost-preventing layer, and subbase course are obtained from the buried plate-loading apparatus on each layer of pavement before freezing and after thawing. From these coefficients, the moduli of deformation for the layers of these materials were calculated using the approximate calculating method of multilayer-displacement, and the structures of pavements were theoretically analyzed. The performance of pavements at the Bibi Test Road was analyzed on the basis of the assessments on the test road through traffic loads.