8th International Conference on Managing Pavement Assets PAVEMENT MANAGEMENT FOR PERMAFROST CONDITIONS

Permafrost by definition is permanently frozen ground. It is composed of an upper active layer that thaws and refreezes each year. It is underlain by a passive layer that remains permanently frozen. This layer may range from a metre to over 100 metres in thickness and in many cases, this layer is ice-rich. In the case of discontinuous permafrost, its temperature is approximately-1 0 C and consequently minor changes in the thermal regime such as adding a fill to natural terrain will cause this ice to thaw, resulting in major distortions on highway subgrades. The basic concept in constructing highways on permafrost is to keep the ground frozen. Various techniques have been developed over the years with varying levels of success to prevent the underlying layers from thawing. Bituminous Surface Treatment performance data has been collected for a poorly performing highway on permafrost that was constructed some 50 years previously. This performance is compared to adjacent sections constructed with modern technology. Many of these sections showed considerable distress after construction and pavement management data is also used to evaluate whether the performance of the highway is stabilizing with time. It was expected that the sections constructed using modern technology would in general, provide better performance. However the performance of individual sections has been disappointing. In summary, the findings are that recent developments in permafrost construction technology have made some improvements to BST performance but more work is required to develop longer term solutions