Public Works Department

Chip Seal

Chip Seal is the application of a special protective wearing surface to an existing pavement. It is a cost effective method to extend the pavement life of a roadway.

Why Chip Seal?

• To keep water from penetrating the road structure on paved surfaces.
• To seal the pavement surface, minimizing the effects of aging.
• To fill and seal cracks and raveled surfaces of old pavement.
• To provide an anti-glare surface during wet weather and an increased reflective surface for night driving.
• To provide a highly skid-resistant surface, particularly on wet pavements.
• To help eliminate black ice situations.
• To maintain many road for a lower cost.

How Cost-Effective is Chip Seal?

The chip seal process typically costs $2.50 per square yard. By comparison, milling off the road surface and putting down a new overlay of asphalt costs about $15 per square yard. This means that a typical 1 mile of a roadway would cost about $35,000 to chip seal but about $200,000 to mill and overlay. Which means that the cost of chip seal is about 15%-20% of the cost of pavement overlay.

The Chip Seal Process

1. First, asphalt is mixed with about 30% water. This emulsified mixture is then applied to the road using a special spray truck. As soon as the liquid asphalt meets the road surface, the water starts to evaporate.
2. Immediately after spraying this asphalt, a layer of crushed gravel is applied by a spreader. The gravel (or chips) has a maximum size of 3/8 inch.
3. Next, the gravel is compacted and embedded into the asphalt by rubber-tired rollers. However, even with the high pressure rolling, some gravel will not become embedded in the asphalt.
4. The new chip-seal surface can require up to two days to cure properly. Hot, dry weather helps speed up this process in which all of the remaining water in the emulsion evaporates and the asphalt hardens. Traffic can pass over this surface at reduced speeds during the curing process. The recommended speed is 15 mph.
5. After curing, the loose gravel is swept off the surface. This may take several sweepings.
6. Fog seal treatments might be applied after a few weeks to help better lock those chips in place and give the surfaces darker color.

Safety Tips

During chip seal operations, and several days afterwards, drivers are advised to drive more cautiously. Reduced speeds ensure your safety and minimize the chance of damaging your vehicle. During the chip seal process, from the time the gravel is placed on the road to when the excess is swept away, the speed limit is 15 mph. At that speed, drivers protect their vehicles from unnecessary damage that can be caused by the sprayed asphalt and loose gravel. Traffic moving at higher speeds can create dust, limit visibility, and cause an inconvenience to local residents. Increased speeds can also cause gravel to break loose from a fresh chip seal creating the risk of flying rock. Additionally, by driving slow you help to compact the new surface.

We Appreciate Your Patience

Throughout the year, the Southbury Public Works keep making improvements to town roadways which may cause some traffic delays. Please be patient. Traveling at the posted construction speed limit in construction zones will ensure your safety and the safety of Public Works employees. Obeying warning signs and flagging personnel instructions benefits all those who share the roadway with you, too.