Frost heave of roads

Summary The mechanism by which frost heave occurs when freezing temperatures, frost-susceptible materials and an adequate supply of water occur simultaneously is outlined. Index tests for identifying frost-susceptible materials (particularly sub-base aggregates) are discussed and emphasis is given to improvements in the Transport and Road Research Laboratory (TRRL) test and the role of suction/permeability relationships. Analysis of the design procedure to prevent frost heave damage highlights the importance of material and environmental factors. Results from homogeneous and composite specimens support this conclusion. A quantitative model has been developed and reasonable agreement obtained between its predictions and the heave observed in a Precise Freezing Cell. The work described is relevant to the improvement of empirical design procedures in the near future as well as the possible introduction of analytical design methods at a later stage.