Granular protection design to minimize differential icing on insulated pavements

The presence of an insulating layer in pavement structures generates a cooling effect at the surface. This can lead to slippery conditions on insulated pavement sections, while adjacent conventional pavement sections have dry surfaces. One way to control the occurrence of this phenomenon, known as differential icing, is to place a granular layer on top of the insulation. This paper proposes a rational design approach that considers climate conditions, as well as the properties of the pavement materials, to establish the minimum thickness of the granular protection layer needed to reduce the risk of differential icing. The proposed approach is illustrated with typical cases at various locations in Quebec, Canada. Design charts are developed to determine the minimum thickness of the granular protection layer as a function of the local mean annual air temperature, the thickness of the insulating layer, as well as the mineral content and the water content of the granular materials.