Should rain cause delays for your crew? This common question can mean different things to different people because of the wide range of precipitation encompassed by the word “rain.” On one end, occasional light sprinkles should not be cause to shut down operations. However, a steady downpour, either light or heavy, should result in cessation of paving activities. To avoid waste, some states have verbiage in their specifications stating that trucks in route to the project when rain begins can be laid at the contractor’s risk.
Also keep in mind that the surface on which you are paving may influence your decision. Paving on a firm, stable, well-draining crushed aggregate base might be given more leeway than a thin asphalt overlay. Raining or not, new pavement must be placed on a firm, unyielding base.
Critical ideas to keep in mind when dealing with rain:
- rain will cool the asphalt mix and could make obtaining proper compaction more difficult
- the asphalt lifts must be able to properly bond together and moisture can be a hindrance to that bond
- puddles overlaid with HMA turn to steam, which may cause stripping (separation of the asphalt binder from the aggregate) – never pave over puddles whether it is raining or not
If you temporarily suspend paving operations due to rain, don’t forget to:
- keep all trucks tarped
- construct a vertical-faced construction joint
- properly dispose of all material left in the hopper
- be careful not to track mud and dirt onto the project
Asphalt pavements are designed to last for many years, so don’t let a sense of urgency to get the job done quickly allow you to make decisions which could strip years away from the pavement life.