Sealing of the roadway begins with sealing all cracks in the roadway which are ¼” wide or wider.   Prior to sealing cracks, the pavement must be dry and temperatures must be warm (over 60º F).  Cracks are cleaned with compressed air and then sealed with a hot-applied asphalt-based adhesive product that solidifies quickly and cures over several weeks into a hard, flexible material designed to resist cracking.  Once the cracks are sealed and enough time has passed for the crack sealant to cure, a slurry seal is spread along the roadway if necessary.  Crack sealing is a fairly quick process and a crack sealing team is usually on and off a street in a couple hours, depending on the number of cracks in the roadway.

Pavement sealing is performed as either a slurry seal or micro seal which are a water/oil/aggregate mixture that is in liquid slurry form and is not like the asphalt overlay many people are familiar with.  Pavement seal is applied to help preserve and protect the underlying pavement structure and provide a new driving surface. Pavement sealing provides the most cost-effective benefit to good condition pavement.  Pavement seal applications serve to seal cracks less than ¼”, restore lost flexibility to the pavement surface, and help preserve the underlying pavement structure.  Micro seal has the added benefit of filling ruts/dips in the roadway surface by including polymer additives that give the mix greater stability that allow for a thicker application. Depending upon a roads Pavement Condition Index (PCI), a pavement seal or pavement overlay may be recommended.  Pavement seal treatment is best applied to roads that are in good condition (70-100 PCI), and which have not yet developed structural damage; pavement sealing keeps good roads good and allows the road to have a much longer service life before costly structural repair or replacement projects are needed! 

Similar to crack sealing, pavement sealing must be done when pavement is dry and temperatures are warm.  Prior to sealing, roads are swept of loose material, utility lids and concrete surfaces (such as gutters) are covered to protect them from the seal coat, and edges of pavement are cleared of soil and vegetation.  Pavement seal trucks contain various compartments which hold the aggregate (fine crushed rock), water, oil, and other additives, which are mixed in the on-board mixer. The slurry mixture flows out of the rear of the truck and distributes the mixture over the pavement. Workers with squeegees follow behind and assist in spreading the mixture, correcting areas not properly covered, and keeping the mixture off of concrete surfaces.   Once placed, the seal mixture needs at least 4 hours to set before the road is open for traffic. Once the seal has cured sufficiently, the roadway is reopened. After the seal is applied, any striping needed is reinstalled on the roads, and the streets are swept for loose aggregate. Initially, the roads appear and feel much rougher than they were previously but return to normal roughness over the span of several months.  Pavement sealing requires extensive work and activity on a roadway will take most of a day to complete.  During pavement seal operations and for four hours afterwards, the roadway is closed to all vehicles.  

After the seal is placed, the roadway will be rough but will smooth out as loose aggregate dislodges from the surface of the roadway. This is typical and during this transition time, streets will be swept after the first week, third week, and then again after 3 months from the date the seal was completed.

When a Pavement Condition Index (PCI) rating dips below 70, pavement sealing is no longer cost effective and 2” overlay becomes the next step in preserving the roadway.  Prior to paving, the contractor's crew will repair deteriorating sections of pavement, grade the shoulders to expose the edge of asphalt, trim any low overhanging trees or shrubs that will be in the way for the dump trucks, and perform any other work necessary to prepare the roadway surface for paving.  Up to seven days before the overlay paving begins, crews will grind up to 2” of pavement from the surface.  Once the grinding is completed, the new asphalt will be placed and rolled to maximum compaction.  Once the pavement has cooled sufficiently, vehicles may drive on the new surface. 

Paving work requires numerous pieces of heavy equipment to haul, place, and roll the asphalt. Due to the nature of paving and the amount of equipment needed, the work zone can be quite lengthy and will cause significant traffic delays during construction hours. Always watch for equipment, flaggers, and workers along the road when driving through a work zone, and expect reduced speed limits and increased delays in getting to your destination. We appreciate your patience while the paving is underway. Crews will make every attempt to work efficiently and effectively. On the higher volume arterial roadways, the contractor will place variable message boards to give motorists advanced notice of possible paving delays.

As part of the overlay work, any curb ramps that provide access across the newly paved road that do not meet the American’s With Disabilities Act (ADA) guidelines must be removed and replaced with ADA compliant ramps.  If, at the intersection, curb exists with no curb ramp, a compliant curb ramp must be installed. 

2020 asphalt overlay project:  Simonds Rd NE between NE 163rd Pl and 92nd Ave NE

In the days following the paving and pavement seal, crews will be on site to perform work such as installing traffic markings, placing crushed rock along gravel shoulders and driveways, and adjusting/clearing utility valves and manhole covers. Drivers can expect delays during these activities but these delays are generally much shorter than those experienced during the overlay/pavement seal phases.