When can the friction course be placed?

The friction course in asphalt paving is designed to provide a textured surface that enhances skid resistance. It is essential for achieving proper performance characteristics in a roadway. The correct timing for placing the friction course is contingent on several factors related to the underlying layers and the overall paving process.

The answer indicating that the friction course can be placed when the shoulder has been dressed and grassed highlights the importance of preparing the surrounding area before the final layer is applied. Dressed shoulders ensure that the pavement structure is supported adequately and that erosion or damage does not occur post-installation. This preparation helps ensure that the pavement can perform well under traffic loads.

For proper application and to avoid issues with adhesion or structural integrity, the other options do not capture the appropriate conditions for laying down the friction course. While the completion of the asphalt base is necessary, simply laying it down is not sufficient for a proper installation. Similarly, while curing is vital, merely waiting for the base layer to cure without considering surrounding protections might undermine the overall quality of the project. Lastly, having an inspection by the engineer, while critical for quality assurance, does not directly relate to the physical preparation of the area necessary for applying the friction course. Thus, the focus on the shoulder dressing aligns with ensuring that the