2020 Street Maintenance Project
Each year, the city performs street and trail preservation activities in different parts of the city as part of a long-term program. Pavement preservation work for the 2020 construction season will include seal coating, crack sealing and fog sealing within segments of city streets and trails as shown on the attached 2020 Sealcoat Map (PDF).
A Schedule should be available in early May.
The seal coat process involves cleaning the existing pavement surface, spreading an asphalt emulsion, placing and rolling aggregate on top of the emulsion, and sweeping up the excess aggregate. A second sweeping is conducted two or three days after the application to remove the remaining loose aggregate.
The primary reason to seal coat an asphalt pavement is to protect the pavement surface from deterioration by sun and water. When an asphalt pavement is exposed to sun, wind and water, the asphalt hardens, or oxidizes. This causes the pavement to become more brittle. As a result, the pavement will crack because it is unable to bend and flex when exposed to traffic and temperature changes.
Crack sealing involves the application of a bituminous sealant into pavement cracks to minimize water from seeping into the subgrade below the pavement and causing deterioration. Crack sealing is one of the more cost effective methods for extending the service life of street pavements.
Fog sealing is typically applied to cul-de-sacs and recreational trails. It involves the application of a diluted asphalt emulsion on pavements without the use of seal coating aggregate described above. Fog sealing has similar benefits to a seal coat to protect the pavement surface from the deteriorating effects of sun and water. Fog sealing provides a waterproof membrane which slows the oxidation process and helps the pavement shed water, preventing moisture from entering the base material. It also provides a clean black surface to aid in snow and ice melting.
The City is using fog sealing in cul-de-sacs to minimize historical problems associated with high volumes of turning movements. During the warmer summer months, seal coat areas have a tendency to shift or tear when turning movements occur. Garbage and recycling trucks with their large tandem base can often create tearing issues on seal coat surfaces, along with cars backing out of there driveway and turning their ties while not moving.
Assistant City Engineer
Email David Swearingen