In the last twenty years, I have personally driven over five hundred thousand miles. In that time I have seen many new pavement projects constructed in many different areas. There is one thing that I have personally witnessed on many occasions when those construction projects fail prematurely. Areas where Tack coat should have been used has failed. Some examples are the following. Within two to three years after construction, potholes and spawling appears at longitudinal joints where the adjacent lane was constructed on a separate day. Another is where it could clearly be seen that a core sample location had been filled, and a short time later there is a pothole in the location. The worst is when a roadway has had a mill two pave two project, and within two to three years, there is large scale spawling of roughly two inches.
I have witnessed this in many locations; not just in New Jersey. If the tack coats that are being used to bind two layers together are not performing effectively, then the entire pavement will have a dramatically shorter lifespan than designed for. A comprehensive study of this problem will lead to much more effective tack coats and stronger joints in our pavements. This will translate into improved lifespan of our roadways and a reduced cost of repair and reconstruction.