What should be done if dirt, sand, or other impurities contaminate the tack coat?

If dirt, sand, or other impurities contaminate the tack coat, it is crucial to remove those impurities and reapply the tack coat. The tack coat plays a vital role in ensuring proper adhesion between layers of asphalt, and any contamination can severely compromise this bond. Contaminants can prevent the asphalt layers from properly adhering to each other, leading to potential failures such as delamination or premature surface cracking.

Removing the impurities ensures that the surface is clean and prepared for optimal adhesion. After cleaning, reapplying the tack coat creates a suitable bonding surface for the next layer of asphalt. This practice is essential for maintaining the integrity and longevity of the asphalt pavement, ensuring that it performs effectively under traffic loads and environmental conditions.

In contrast, applying a seal coat or simply sweeping the surface will not address the underlying issue of contamination. Leaving the contaminated tack coat would lead to bigger problems down the road, such as reduced durability of the asphalt layers.