Modified Chip Seal
Contract-Ready Construction Specification Guidelines
Download GuidelinesLearn about the benefits of Modified Chip Seal Treatments
Modified asphalt and pavement preservation work hand in hand to maintain the public driving experience. A modified chip seal extends the serviceable lifetime of roadways in low to medium distress situations. With a polymer modified asphalt binder as a base, a modified chip seal is ideal for superior aggregate retention that allows for a quick return to traffic.
The use of a modified chip seal extends the life of a roadway by roughly 6-7 years and reduces life-cycle costs.
Modified chip seals can be used to prevent or repair areas of oxidation, top-down fatigue cracks, raveling or loss of friction. However, they are not recommended for unsealed cracks larger than ¼” or ruts deeper than ⅜”. The benefits of modified chip seals are not limited to preservation, as they can also be used to update a gravel road to a paved road.
Gansberg completed research on the many different types of binders and sealers used for roadway preservation. He found that modified chip seals were ideal for roadways with medium to high daily traffic volume as they were found to be less likely to break down under higher stress due, in part, to the modified aggregate binder.
Best Practices
- Follow a prepared design.
- Seals cracks larger than ¼”.
- Use a single-size, clean stone.
- If necessary, adjust target rates depending on field conditions.
- Calibrate all equipment. Do not over apply aggregate.
- All traffic, including construction equipment, should be controlled to less than 35mph until final sweeping.
Pavement Preservation Success
Success Story: Modified Triple Chip Seal
DownloadIn 2005, the Georgia Department of Transportation (GDOT) moved away from chip seal treatments due to vehicle damage caused by loose stone and friction loss related to bleeding. However, GDOT sought to bring the process back by changing both the construction methods and the materials used. The GDOT Maintenance Department determined that a pilot project, called a triple chip seal, would be the most appropriate way to test the new approach.