Types of Treatment
The City evaluates several factors when prioritizing which streets to resurface and estimating treatment costs. These include pavement condition, traffic volume, functional classification, location, maintenance history, drainage, environment, and age. The Pavement Condition Index (PCI), rates streets on a scale of 0 to 100 based on the type and severity of pavement distress this rating helps the City monitor pavement health and schedule timely repairs.
About Treatment Types
The City uses a combination of preservation and rehabilitation treatments to maintain its roadway network. Preservation focuses on protecting streets that are still in good condition, while rehabilitation restores those that have deteriorated. By applying the right treatment at the right time, the City extends pavement life and uses public funds efficiently.
Common Terminology
Alligator Cracking: Alligator cracking is a type of asphalt damage characterized by a series of interconnected cracks resembling an alligator’s skin.
Asphalt: A composite material that is made up of aggregates and bitumen. The aggregates are a mix of crushed stone, gravel, and sand. Bitumen is the dark, sticky material that holds the aggregates together.
Asphalt Emulsion: A combination of three basic ingredients, asphalt, water, and small amount of an emulsifying agent.
Aggregate: Granular materials like sand, gravel, and crushed stone used as a foundational component in concrete, asphalt, mortar, and road bases.
Base: The layer of a road that comes between the subgrade and the top layer. Road base is used to strengthen the top layer (asphalt or concrete) and provide drainage. Road base also helps distribute weight, to reduce cracking of the road over time.
Blocking: Interconnected cracks that divide the pavement up into rectangular pieces.
Cement: A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together.
Foamed Asphalt: Foamed asphalt is formed by combining hot asphalt binder with small amounts of cold water. When the cold water meets the hot asphalt binder it turns to steam, which becomes trapped in tiny asphalt binder bubbles. The result is a thin-film, high volume asphalt foam with approximately 10 times more coating potential than the asphalt binder in its normal liquid state.
Milling: Pavement milling, also called asphalt milling, cold milling, or cold planing, is a process of removing part of the paved surface, covering roads, driveways, bridges, or parking lots. Milling is completed using a machine with a rotating drum to grind and remove the top layer of asphalt or concrete, preparing it for new pavement or resurfacing.
Raveling: The deterioration of pavement by the loss of asphalt and rocks. This is evident by the rocks and sand on the pavement surface and in gutters.
Rutting: A permanent depression or groove in the pavement caused by repeated heavy vehicle traffic.
Subgrade Failure: Failure of the native material underneath a constructed road, which can cause depressions and rutting of the upper base and surface pavement layers.
Transvers Cracking: Single cracks perpendicular to the pavement’s centerline or laydown direction.
Preservation (Surface Repair Only)
Preservation treatments are used on streets in good to excellent condition, generally with a PCI of 70 or higher. These methods seal small cracks, protect against water intrusion, and provide a fresh wearing surface.
Fog Seal
A fog seal is a thin spray of asphalt emulsion applied to the pavement to refresh and seal the surface. It restores flexibility, darkens faded pavement, and helps protect against sun and water damage. Fog seals are commonly used as preventative maintenance in City parking lots. Typically extends the life of pavement by 2–4 years.
Slurry Seal
A slurry seal is a thin layer of asphalt emulsion, fine rock, and water spread across the surface. It seals small cracks, protects against weather, and gives the road a fresh black appearance. It’s most common on neighborhood streets depending on traffic and weather. Typically extends the life of pavement by 5–7 years.
Microsurfacing
Microsurfacing looks similar to slurry sealing but uses a faster-setting mixture that can be applied in cooler weather and opened to traffic more quickly. It’s often used on busier streets where minimizing closure time is important. Typically extends the life of pavement by 7–9 years.
Chip Seal
Chip seals combine a layer of liquid asphalt with small rock chips that are rolled into place and swept once cured. The surface is durable and skid-resistant, making it a cost-effective option for streets starting to show moderate wear. Chip seals may be followed by a slurry or microsurfacing layer to create a smoother finish. Typically extends the life of pavement by 5–7 years.
Cape Seal
A cape seal combines a chip seal with either a slurry seal or microsurfacing layer on top. The result is a stronger, longer-lasting surface that feels smoother to drive on than a chip seal alone. Cape seals are commonly used on streets with more traffic or where added durability is desired. Typically extends the life of pavement by 8–10 years.Preservation (Surface and Minor Subsurface Repairs)
Some preservation methods require subsurface treatments, in addition to the surface treatments listed above, to help maintain the life of the pavement and prevent the need for full rehabilitation.
Localized Digout and Replacement
To repair localized rutting, blocking or potholes a section of the asphalt and underlaying aggregate is removed and replaced with new aggregate, compacted and repaved. The replaced section will have a life of 20+ years.
Grind and Inlay
This process starts by grinding the top layer of old asphalt to create a smooth, even surface. A new layer of hot mix asphalt is then paved over it. The result is a smoother, stronger roadway that restores ride quality are used when the base is still solid, but the surface is worn or uneven. Typically extends the life of pavement by 10–15+ years.
Rehabilitation (Full Section Repair)
Rehabilitation methods are used when a street has significant cracking, rutting, or base failure, typically with a PCI below 50. These projects take longer and require heavier equipment but provide much greater structural improvement.
Full‑Depth Reclamation (FDR)
Full Depth Reclamation rebuilds the road from the ground up by recycling the existing asphalt and base material in place. The pulverized mix is blended with cement or foamed asphalt to form a new, stabilized foundation, and a fresh asphalt layer is placed on top. This process greatly reduces trucking and waste while producing a strong, durable road for long-term use. A reconstructed road can have a life of 20+ years with preservation treatments.
Reconstruction
This method involves completely removing the existing pavement and rebuilding it with new materials. It’s used when both the surface and base have failed. After excavation, the base is repaired or replaced, and new hot mix asphalt is placed and compacted. It’s the most intensive option but provides a fully renewed roadway. A reconstructed road can have a life of 20+ years with preservation treatments.
FREQUENTLY ASKED QUESTIONS
FREQUENTLY ASKED QUESTIONS
Why is my street getting slurry instead of new asphalt?
Preservation treatments keep good streets good at a fraction of the cost, stretching funding and extending the life of the pavement.
How are streets selected?
We use PCI data, traffic volumes, safety, equity, and coordination with utilities to build an annual program approved by City Council.
Will there be loose rock from chip seals?
Crews sweep soon after placement and again as needed. Please drive slowly until sweeping is complete.
What can residents expect during construction?
- Advance notices and posted “No Parking” signs where needed.
- Temporary lane or street closures with detours. Please follow flaggers and signage.
- Fresh surfaces may look dark and feel coarse at first; ride quality improves after sweeping and final striping.
What about ADA facilities?
Some surface treatments (like microsurfacing and grind and inlay) can trigger ADA curb ramp upgrades when streets are resurfaced. The City evaluates ADA work and budgets accordingly.
