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IRC tackles reflective cracking problem in pavements
Every day, road agencies in Canada and around the world face a common problem in their efforts to rehabilitate roads. This problem is reflective cracking, which is the propagation of cracks from the existing pavement into the layer of pavement added (overlay) during rehabilitation. Such cracking requires frequent maintenance and rehabilitation, imposing a budgetary burden on highway authorities.
Information currently available to pavement engineers does not explicitly take reflective cracking into account, thus contributing to the extent of the problem.
To help provide effective measures for preventing reflective cracking, IRC is developing analytical tools to predict the reflective-cracking potential of pavements. It is undertaking this research because there is general consensus among those responsible for the construction and maintenance of roads that current pavement design methods do not result in long-lasting overlays for cracked asphalt pavement. Many of the road rehabilitation measures used today, which involve increasing overlay thickness, modifying material properties, and placing stress-relieving layers at the interface between the existing pavement and the overlay, are not very effective - cracks continue to be reflected from the existing road into the overlay.
Information currently available to pavement engineers does not explicitly take reflective cracking into account, thus contributing to the extent of the problem. For example, in many design procedures currently in use in North America, the thickness requirement is based only on the pavement's structural capacity to meet future traffic demands and not on in-service conditions such as the presence of cracks. As a consequence, future road performance cannot be adequately predicted.
The analytical tool now being developed by IRC will take existing in-service conditions into consideration, since in order for overlays to last, the potential of existing cracks to be reflected, due to either traffic or environmental loads, needs to be recognized at the structural analysis and design stages. By considering these factors, IRC's approach will help pavement engineers evaluate various strategies for preventing cracks and selecting the most durable and economical rehabilitation option.
