Crack seal is a treatment mainly used to prevent costly measures to your asphalt. When the moisture penetrates under the surface it can create a soft spot which can turn into a pot hole. Cracking is caused either by thermal stresses or from fatigue due to repeated traffic loading. The vast majority of potholes and pavement failures can be traced to water entering the base and sub-grade through joints that have not been crack sealed in both concrete and asphalt. In most pavements, the base, sub-base or sub-grade consists of a material that loses its load-carrying capacity when wet. Water enters through the cracks and traffic works and overloads the weakened areas allowing more and more water to enter. This can cause potholes to develop rapidly and more severe pavement failures if left unsealed. Water is the most destructive element to the pavement when water is kept out deterioration is slowed.