We have a low-volume local road that was reconstructed two years ago. It is now showing cracks in the center of the travel lane, running parallel to the edge of the road. What should we do?
As a rule, any cracks greater than ¼" in width should be repaired. If left alone, there is the potential for excess water to infiltrate into the pavement's base, causing a weakening of the base material, resulting in additional cracks. This eventually causes the pavement to fail. Crack repairs should be done as soon as possible or the deterioration will be so great that more expensive repairs such as an overlay or even recycling will be needed.
The type of cracking described here is referred to as 'longitudinal cracking' which can be caused by several factors. As further described in the CLRP workshop manual Asphalt Paving Principles, longitudinal cracking can result from one or more of the following:
- the inability to compact an unconfined edge of the paving pass (typically found at the edge of the pavement or at the center line)
- segregation attributed to a certain brand of paver
- frost heaves in the base or subgrade
The type of repair is dependent on the type of crack, working or non-working, and the width of the crack. If the crack is a 'working crack' and exhibits movement equal to or less than 1/8" from winter to summer, it may be sealed by placing specialized material either into or above the crack to prevent water and/or debris from entering the crack. The ideal time to fill cracks is on a sunny day in the spring or in the fall, when the crack is at the middle of its working range. This reduces the stress on the sealant. If the crack is a 'non-working crack' and between ¼" and 1", it should be filled. All cracks should be clean and dry prior to the placement of either the sealant or the filler. Please refer to the CLRP workshop manual Pavement Maintenance for specific recommendations regarding each method of repair.
Materials and procedures for Sealing and Filling Cracks in Asphalt-Surfaced Pavements: Manual of Practice (FHWA Report No. FHWA-RD-99-147). (PDF)