The challenges of paving asphalt in rainy conditions

By Dr. Amma Wakefield, Ph.D., P.Eng.

Inspired by a recent photo I came across, I wanted to shed some light on the difficulties that arise when paving asphalt mix in wet weather. While the image captures the determination of the paving crew, it also highlights the issues faced during such conditions.

Paving asphalt in the rain can result in several challenges that compromise the quality and durability of the pavement. Here are a few key points to consider:

1. Poor adhesion: Rainwater acts as a barrier between the asphalt mix and the underlying surface, hindering proper bonding. This weakens the pavement’s overall integrity and may lead to premature failure.

2. Reduced compaction: Achieving optimal density and strength through compaction is essential for a robust pavement. However, rainwater makes the asphalt mix more difficult to compact, resulting in insufficient density, structural weaknesses, and increased vulnerability to damage.

3. Surface defects: The infiltration of rainwater into the asphalt mix can cause surface irregularities such as raveling, rutting, and potholes. The water displaces the binder, weakening the surface and leading to the formation of cracks and other defects.

4. Safety hazards: Paving in wet conditions poses safety risks for workers due to slippery surfaces. It also reduces visibility, increasing the chances of accidents for both construction workers and drivers in the vicinity.

To ensure the best outcome, it is generally advisable to schedule asphalt paving projects during dry weather. This allows for proper compaction and adhesion, ultimately resulting in a more durable and long-lasting pavement.

Remember, a well-executed paving project sets the foundation for safe and reliable transportation infrastructures. Let’s prioritize optimal conditions for asphalt paving and work towards creating long-lasting roads.

Wakefield is the Canadian and Research Engineer for the Asphalt Institute. She is based in Ontario.