How long must a new tack coat be applied after the original one if contaminations are present?

The correct answer reflects the best practice in managing tack coats when contamination occurs. When contaminants, such as dust or moisture, are present, they can significantly affect the bond between layers of asphalt. A new tack coat is necessary to ensure proper adhesion; however, it is crucial to allow time for the original tack coat to cure properly before applying a new one.

In the presence of contaminants, waiting more than three days is recommended because it allows for adequate drying and curing time. It also ensures that any issues caused by the contaminants are resolved, promoting a stronger and more durable bond. A greater duration helps reduce risks such as inadequate adhesion, which could lead to premature failure of the road surface.

Understanding the timing for reapplication of tack coats under different conditions ensures that best practices are followed in asphalt paving, ultimately resulting in longer-lasting and more resilient pavement surfaces.