Pavement Treatment Types

Pavement Preservation

Pavement preservation is proactive maintenance to prevent roads from deteriorating to a state where major rehabilitation or reconstruction is necessary. Preventative maintenance costs are much less than ultimate repair costs. As pavement ages, its condition declines to a poor state after approximately 75% of its life (typically 20 years). Proactively maintaining roads extends their lifespan, maximizing the value of each dollar spent. This approach allows for preserving more streets compared to fixing badly damaged roads first.

Fog Seals

- What? A fog seal is a specially formulated asphalt emulsion (a thin liquid oil) applied to an existing asphalt pavement surface.

- Why? It seals narrow cracks, restores lost flexibility, provides a rich black surface color, and helps preserve the underlying pavement structure.

- When? Typically applied intermittently or cyclically every three to five years on roads with minor cracking and faded color.

- How? Applied by a distributor truck, which heats the asphalt emulsion before spraying it onto the pavement, giving it a black, spray-painted appearance.

Slurry Seals

- What? A slurry seal is a mixture of water, asphalt emulsion, aggregate (very small crushed rock), and additives applied to an existing asphalt pavement surface.

- Why? It preserves and protects the underlying pavement structure and provides a new driving surface.

- When? Typically applied intermittently or cyclically every five to seven years on roads with slight to moderate distress and narrow crack widths.

- How? Applied using a slurry truck, which mixes and distributes the slurry mixture. Workers assist in spreading the mixture and ensuring coverage.

Microsurfacing

- What? Similar to slurry seal but hardens quicker due to chemical additives in the asphalt emulsion.

- Why? Preserves and protects the underlying pavement structure and provides a new driving surface.

- When? Applied intermittently or cyclically every five to seven years on roads with slight to moderate distress and narrow crack widths.

- How? Applied using a slurry truck or continuous machine, which uniformly distributes the mixture across the pavement.

Chip Seal

- What? A two-step process applying asphalt emulsion and then a layer of crushed rock to an existing asphalt pavement surface.

- Why? Seals narrow cracks, binds cracked pavement, provides a driving surface, and protects the underlying structure.

- When? Applied intermittently or every seven to ten years on roads with moderate block cracking and no rutting.

- How? Asphalt emulsion is applied by a distributor truck, followed by crushed rock applied by a chip spreader. Rollers enhance the bond, and sweepers remove loose rock.

Prep-work

- What? Work performed before applying any treatment, including repairing severe damage and cleaning the pavement.

- Why? Ensures the benefits of the maintenance treatment are maximized and the new treatment bonds properly.

- When? Necessary when there are isolated areas of failure to maximize the benefits of any maintenance or rehabilitation treatment.

Rehabilitation

Rehabilitation is performed on pavements that exhibit distresses beyond the effectiveness of maintenance but are not yet in need of complete reconstruction.

Rubberized Asphalt

- What? Hot-mixed asphalt pavement containing crumb rubber from processed scrap tires.

- Why? Provides a longer-lasting, more durable surface, reducing maintenance frequency.

- When? Used as the surface course material for resurfacing or reconstruction projects, typically lasting 14 to 18 years.

- How? Crumb rubber is added to liquid asphalt either at the asphalt plant (field blend) or at a refinery (terminal blend) before being mixed with aggregate and placed using a paving machine and rollers.

Cold In-Place Recycling (CIR)

- What? A process involving a milling machine that breaks and pulverizes the top layer of old pavement, mixes in recycling agents, and then spreads and compacts the material.

- Why? Treats a wide range of pavement distresses, improves ride quality, and provides cost savings.

- When? Suitable for applications where underlying soil structures are adequate.

- How? The recycled material is compacted using various rollers and sealed with an overlay or double surface treatment.

Cold Central Plant Recycling (CCPR)

- What? Recycling reclaimed asphalt pavement (RAP) with an asphalt emulsion to rejuvenate it.

- Why? Provides better process control, environmental benefits, and cost savings.

- When? Selected when precise process control is required or when incorporating RAP from other projects.

- How? RAP is processed and rejuvenated at a central plant before being applied to the pavement.

Asphalt Overlay

- What? Applying a new layer of asphalt over the existing pavement.

- Why? Uses existing layers as a base for the new asphalt, rather than completely removing the old surface.

- When? When the existing pavement is stable and does not require repairs or replacement.

- How? The existing surface is cleaned, a tack coat is applied, and then the new asphalt is placed.

Mill and Fill

- What? Removing the existing surface layer and replacing it with new asphalt.

- Why? Restores and strengthens the road’s surface when it has deteriorated to poor condition.

- When? When pavement preservation treatments are no longer effective and structural reconstruction is required.

- How? The damaged asphalt is milled away and replaced with new asphalt.

Reconstruction

Reconstruction becomes necessary when pavement deteriorates beyond the point where rehabilitation is cost-effective or effective.

Full-Depth Reclamation (FDR)

- What? An in-place recycling method using existing pavement material as the base for a new surface.

- Why? Provides a cost-effective solution, enhances structural capacity, and reduces environmental impact.

- When? Used when traditional remove and replace reconstruction is impractical.

- How? The existing pavement is pulverized and treated with mechanical, chemical, or bituminous stabilization methods to create a strong foundation for the new roadway.

Lime Stabilization

- What? Adding lime to asphalt pavements to enhance durability.

- Why? Improves resistance to moisture damage, enhances stability and durability, and reduces oxidation and aging.

- When? When increased durability and improved pavement properties are required.

- How? Lime is mixed into new hot-mix asphalt or applied to existing pavements as needed.