Application of Tack Coat
The application of a tack coat in micro surfacing is a crucial step to ensure proper adhesion between the existing pavement surface and the micro surfacing material. Tack coats are bituminous emulsions that act as bonding agents, promoting a strong and durable connection between the old pavement and the new micro surfacing layer. Here’s a guide on the application of a tack coat in micro surfacing:
- Surface Preparation:
- Before applying the tack coat, ensure that the existing pavement surface is clean, free from debris, and in good condition. Address any cracks, potholes, or other pavement distress through repairs as needed.
- Selecting the Tack Coat Material:
- Choose an appropriate tack coat material based on the project requirements, environmental conditions, and the type of micro surfacing mixture to be applied. Tack coats are typically asphalt emulsions, and the selection may include cationic or anionic emulsions with specific properties.
- Application Rate:
- Determine the proper application rate for the tack coat. The rate is usually specified by the project specifications and is influenced by factors such as the condition of the existing pavement, the type of emulsion, and the desired bond strength.
- Spray Application:
- Apply the tack coat using a calibrated spray bar attached to a distributor truck. The spray bar ensures an even and uniform distribution of the tack coat across the pavement surface. The application should cover the entire area where the micro surfacing will be placed.
- Avoid Overapplication:
- Be cautious not to overapply the tack coat, as excess material can lead to drainage issues, uneven coating, and reduced bond strength. Follow the recommended application rate to achieve the desired results.
- Curing Time:
- Allow the tack coat to cure and set before applying the micro surfacing. The curing time may vary depending on factors such as temperature, humidity, and the type of emulsion used. It is essential to follow the emulsion manufacturer’s recommendations.
- Surface Check:
- Perform a visual check to ensure that the tack coat has formed a uniform and continuous film on the pavement surface. The goal is to create a sticky, tacky surface that provides a solid bond for the micro surfacing layer.
- Application of Micro Surfacing:
- Once the tack coat has cured and the surface is prepared, proceed with the application of the micro surfacing mixture. The tack coat facilitates the adhesion of the micro surfacing material to the existing pavement, ensuring a strong and durable bond.
- Quality Control:
- Implement quality control measures throughout the process, including checking the tack coat application rate, ensuring proper curing, and conducting inspections to verify that the work meets specified standards.
The application of a tack coat is a critical step in the micro surfacing process, as it enhances the bond between the existing pavement and the new surface treatment. Proper tack coat application contributes to the overall effectiveness and longevity of the micro surfacing treatment.