Slurry Seal

The Department of Public Works & Transportation was using the slurry seal process since 1985 and discontinued it for a Modified Surface Treatment in 1998, due to the amount of residential complaints. Slurry seal is a thin asphalt overlay / seal coat that will fill in small cracks and surface imperfections to give the roadway a uniform color and texture. Most importantly it seals the pavement, thus preventing the infiltration of water, which is the most frequent cause of pavement failure. When placed on worn or "polished" roadway surfaces, slurry seal also helps provide a degree of skid resistance. The principal materials used to create slurry seal are aggregate, asphalt emulsion and fillers, which are mixed together according to a laboratory's design mix formula. Unlike "chip seal", there are no loose stones or dust to contend with. There is however, a residue (sandy grit) that remains loose on the finished surface, but it dissipates in a short period of time.

Application

Slurry seal is textured, skid resistant, flexible, waterproof, and has good cohesion which allows it to be an economic and hard wearing surface. The process adds no structural strength to the pavement section, but does result in an extended service life of five (5) to eight (8) years depending on the volume of traffic. Approximately $150,000 was dedicated to this program which treated an average of 30 miles of roadway every other year. A seal coat adds compounds which help reverse the effects of oxidation which causes pavements to become increasingly brittle over time. This treatment is typically applied to newer asphalt roads which do not have significant deterioration.

Schedule

Work is typically performed during the months of June and July, weather permitting, at a unit price of between $0.81-$0.88 per square yard. This application is typically most effective on low volume subdivision roadways and is ready for use just hours after application. Traffic is typically restricted to one lane during paving operations and needs to cure for 2-4 hours, depending on weather conditions, before it can be opened to traffic. If an unopened section must be crossed it is requested that the motorist / resident wait at least five (5) minutes once it has been paved. Residents are advised in writing that if they travel on a closed lane that they may damage the road and may possibly soil their car(s) with asphalt. Intersections and heavy traffic areas are sanded/dusted to keep traffic moving and roadways open.

Types of Slurry

Aggregate types are I (1/8" fine), II (1/4"general), and III (3/8"coarse). Fine aggregate mixtures are used for maximum crack penetration and sealing in low density/ low volume traffic areas. Type II aggregates are the most commonly used where moderate to heavy traffic is found. Type III corrects severe surface defects and prevents hydroplaning and proves skid resistance under heavy traffic conditions.

Cape Seal

It is often that a surface treatment is subsequently slurried (cape sealed) or overlaid with asphalt the following year(s). Cape Seals are used where a chip seal is too rough and requires a smooth finish, for example in residential streets. In instances where cracking is a problem a chip seal can alleviate cracking and the slurry can provide the smooth and hard wearing surface. The addition of a slurry capping not only makes the surface smooth but locks the aggregate of the chip seal in place eliminating stone loss. A cape seal can last longer, can treat cracks, is smoother than a chip seal, more durable than a slurry and could last as long as ten (10) years depending on traffic volumes.

Enforcement

Cars that are not moved are subject to towing at the discretion of the Sheriff's Department. Vehicles and trailers with valid tags may be moved into driveways, relocated to the shoulder area(s) or placed behind curb-lines. Vehicles with invalid/expired tags will be towed to the nearest impoundment yard at the direction of the Sheriff's Department at the owners expense. The Department of Public Works may compensate the owner for the towing costs if the owner can produce valid registration/tags within forty-eight (48) hours. The Construction & Inspection Division can be contacted for more detailed information.