Water is BAD.
Why is water bad?
Water is one of asphalt’s “natural enemies.” Puddles of water on an asphalt pavement will slowly break down the asphalt and cause a pothole to form. Water deteriorates asphalt by breaking the bonds between the asphalt binder and the rocks and sand. Asphalt binder is a by-product produced from crude oil during gasoline production, and water and oil don’t mix.
Water below the asphalt pavement is also an issue. Poor drainage below the pavement can saturate and weaken the supporting materials in the aggregate base and subgrade, allowing traffic loading to cause excess damage to the asphalt pavement.
Additionally, if you read our blog on freeze-thaw cycles, you will know that, during winter, water can get into cracks in the pavement and expand when freezing. This causes the cracks to widen and grow. In addition, water can freeze and expand in large “ice lenses” below the asphalt pavement layer. These ice lenses cause the asphalt to heave upward and then become potholes when the ice melts in the spring.
What can I do to save my pavement from water?
The slope of the pavement is crucial to keep water from pooling on the surface of the pavement. A pavement with little to no drainage slope will quickly develop many puddles (future potholes). Bituminous Roadways recommends constructing new pavements with at least a 1% slope. For existing pavements, routine maintenance is crucial to protect pavements from water damage. Cracksealing, patching, and sealcoating will all extend the life of your pavement by reducing the damage to the pavement caused by water.
Proper subsurface drainage can keep the water moving. Installing an aggregate base with quality class 5 aggregate will allow your base layer to be strong, stable, and to quickly drain water away from the pavement, but this is not always enough. A subgrade made of mostly clay may prevent the water from draining. In some situations, it is best to install a 12”-18” drainable sand layer below the aggregate base layer to improve the drainability of the supporting materials.
Another solution, to improve subsurface drainage, is to install drain tile below the pavement. Drain tile is a highly drainable channel built below the pavement using geofabric as a filter, highly drainable round river gravel, and a perforated pipe connected to a catch basin or storm water pipe.
Bituminous Roadways, Inc. is the Twin Cities’ most respected and sought-after asphalt pavement company. With more than 70 years in the industry, we provide dependable service and the highest level of quality asphalt paving anywhere. Call us today at 651-686-7001 or request a consultation. We proudly serve the Twin Cities metro and the surrounding area.