Frost Heave Protection of Concrete Pavement Subgrades

The Japanese road authority specifies that, in designing pavement subgrade, non-frost heaving materials shall be used for 70% of the frost penetration depth of the subgrade. However, some concrete pavements in snowy/cold regions have been found to have cracks that are categorized as structural damage caused by frost heaving. To examine the necessity for revising the subgrade design, an onsite survey to clarify the frost damage of concrete pavements and an evaluation of the impact of frost heaving on the lifespan of pavements by using FEM analysis and fatigue calculation were conducted. It was estimated from the onsite survey that the void between the concrete pavement and the subgrade, which was generated by frost heaving, would reduce the lifespan of the concrete pavement. To clarify this point, an FEM model was created to reproduce the frost heaving and an analysis was done using this model. In the analysis using the model that reproduced frost heaving, the tensile bending stress due to wheel loads at the bottom of the concrete slab increased. The pavement life was obtained in a fatigue calculation that incorporated the increase in tensile stress. The result was that a concrete pavement had structural cracks in a short period of a few dozen days after it experienced frost heaving. Based on these findings, we propose that, in designing concrete pavement subgrade in snowy/cold regions, it may be appropriate to use non-frost-heave-susceptible materials for the entire frost penetration depth.