Chip Seal Treatment

The following are the most common construction problems with potential solutions. It may take an investigative approach to determine the actual problem.

STREAKING OR DRILLING OF EMULSION:

Potential Solutions

• Verify that the binder is at the correct application temperature
• Ensure that the correct nozzle size is installed
• Verify the nozzle angle is correct
• Make sure all nozzles are clear
• Verify triple overlap coverage

WASHBOARDING:

Potential Solutions

• Reduce aggregate spreader speed.  If the spreader’s forward travel speed is too fast, the spreader will begin to bounce or jump and the aggregate will fall out of the hopper. When this happens, the aggregate will be heavy for a few inches and then light for a few inches then heavy again. This cycle will continue repeating itself until the spreader speed is adjusted.
• Follow correct patching procedures.  Poor patching can also cause this problem.

The following are the most common post-construction problems with potential solutions. It may take an investigative approach to determine the actual problem.

LOSS OF AGGREGATE:

Potential Solutions

• Increase the binder application rate
• Removing the dust off the aggregate or switching to a cleaner aggregate
• Verifying that the aggregate gradation meets specification and is consistent with the mix design results
• Decrease the aggregate application rate to ensure it is not too heavy
• Pre-treat all patches before binder application
• Applying the treatment only when weather conditions are suitable
• Ensure that the aggregate spreaders and rollers were operating closely behind the asphalt distributor
• Control traffic speeds until emulsion is properly set
• Ensure that brooming does not occur before the emulsion is properly set

BLEEDING OR FLUSHING:

Potential Solutions

• Use a cubical shaped aggregate instead of a flat and elongated aggregate
• Reduce the binder application rate
• Increase the aggregate application rate
• Verify that the distributor and aggregate spreader calibrations are correct

For potential remedies on bleeding and flushing chip seals, please refer to Chip Seal Maintenance - Bleeding and Flushed Surfaces.pdf

STREAKED APPEARANCE:

Potential Solutions

• Verifying that the spray bar height is set at 12 inches
• Verifying that all nozzles are set at a 30 degree angle
• Making sure that all nozzles on the spray bar are clean and operating properly