Scrub Seal

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Inspection Guidelines

With scrub seals, like most paving projects, the primary goal is to produce a quality and durable treatment that will protect the underlying pavement. Some of the most important things inspectors can do to help achieve this goal are as follows:

Mix Design: Verify that a mix design has been performed by a qualified lab, and that all test results meet or exceed the specified standards.

Quality Materials: Confirm that the aggregate and emulsion delivered to the job are in conformance with both the specifications and the materials used in the mix design. Best practices include sampling the delivered aggregate to confirm the gradation is within the stockpile tolerance limits.  Also, periodically take a sample of the delivered emulsion for testing.

Equipment Calibration: To ensure proper applicaton rates are placed in accordance with the mix design, the asphalt distributor and aggregate spreader must be calibrated.  

Surface Preparation: Walk or drive the entire pavement to be sealed for the day to ensure the surface has been properly prepared.

Traffic Control: Verify the proper traffic control is in place to keep the traveling public safe and out of the uncured scrub seal.

Acceptable Weather: Measure the air and pavement temperature to determine if construction can start/continue.

Quality Equipment: Verify the asphalt distributor and aggregate spreader is properly calibrated for the materials being used on the project, and the equipment is clean, well maintained, and free of any leaks.

Quality Workmanship: Ensure straight edge lines and quality joints (longitudinal and transverse) are constructed. Verify the finished surface is uniform and consistent in terms of binder and aggregate application rates.

Application Rates: Periodic checks should be made to verify that the amount of material being placed is in accordance with the specifications and appropriate for the gradation of the aggregate being used. Spot checking the yield over a specific pavement area a few times each day is recommended. This can be done by strapping the distributor for emulsion and measuring rock lands for aggregate.  Other methods for tracking the amount of materials placed include keeping a list of the quantities of materials on each truck as they are placed, or tracking the quantities of all materials delivered to the project and deducting for waste.

Additional Resources

This checklist for chip seals could be utilized for scrub seals as well.

Chip Seal Application Checklist: Provided by Federal Highway Administration (FHWA) and the Foundation for Pavement Preservation (FP2).