Part Two: Exploring the Science of Pavement Preservation

Choosing the Right Treatment for Pavement Preservation

Pavement preservation begins with accurate data collection to determine pavement condition index (PCI) ratings.

In part one, we discussed how pavement preservation is a cost-effective strategy to extend the life of a road network. This process relies on analyzing environmental factors, traffic loads, pavement composition, and accurate PCI ratings.

Once these elements are evaluated, agencies can select and apply the most suitable preservation treatment at the optimal time, slowing deterioration and maximizing roadway lifespan.

In part two, we examine how PCI ratings and other key factors guide the selection of the best preservation methods.

Selecting the Right Pavement Treatment at the Right Time

Effective road maintenance involves applying cost-efficient treatments to well-conditioned roads every few years. Treating roads early helps prevent deterioration, reduce water damage, slow asphalt oxidation, and maintain skid resistance. This proactive strategy extends pavement lifespan and minimizes long-term repair costs.

Pavement Condition Index (PCI) ratings guide treatment selection. PCI ratings are based on a 100-point scale and determined through accurate and thorough data collection and analysis. Specific treatments are applied based on the PCI score, traffic load, roadway type (urban, rural, etc.), and pavement composition (asphalt, concrete, gravel, etc.).

PCI Range: 85 – 100

Roads in this range are in good condition but still benefit from pavement preservation treatments to slow deterioration and extend lifespan. Applying top-of-the-curve treatment at this stage ensures roads remain in optimal condition.

The following examples are potential treatment options for roadways in the 85-100 PCI range:

Slurry Seal

Slurry seal is a surface treatment that extends the lifespan of asphalt pavements in the 85–100 PCI range. It prevents moisture intrusion, slows oxidation, reduces raveling, and improves skid resistance while restoring a uniform black surface. This quick, minimally disruptive treatment can add 5–7 years of service life.

Micro Surfacing

Micro surfacing is designed for roads in good condition. This treatment enhances skid resistance, prevents moisture infiltration, and slows oxidation. It is an economical option when minor leveling is required and causes minimal traffic disruption. As a preservation treatment, it can extend pavement lifespan by 6–8 years.

Ultra Thin Lift HMA

This hot mix asphalt (HMA) treatment includes paving-grade asphalt and aggregate, applied at a compacted depth of 0.75” to 1”. It provides a smooth surface while addressing minor surface cracking, oxidation, and raveling. Although it has a higher initial cost, particularly if milling is required, ultra thin lift HMA reduces lifecycle costs and can extend limited budgets. When used as a preservation treatment it can add 8–10 years to the roadway’s lifespan.

PCI Range: 70 – 84

Roadways in this range are in fair to good condition but may require more advanced treatments. While still considered preservation candidates, these roads benefit from treatments that address moderate deterioration, extend lifespan, and delay costly rehabilitation.

Cape Seal

Cape seal treatment combines a chip seal with a slurry seal or micro surfacing to improve pavement durability. This treatment seals moderate cracks improves skid resistance, protects against moisture, and slows oxidation and raveling. It also restores a uniform black surface, making it ideal for urban roads where a standard chip seal may not be suitable. Polymer-modified chip seals improve aggregate retention and allow faster traffic return. When applied preventatively, cape seal can extend pavement life by 8–10 years.

Rejuvenating Fog Seal

A rejuvenating fog seal is used when surface conditions are too deteriorated for a standard chip or fog seal. This emulsion-based treatment restores flexibility by replenishing oxidized asphalt components, slowing further aging. It helps address minor surface cracks, oxidation, and raveling while delaying the need for major maintenance. Depending on roadway conditions, this treatment can extend pavement life by 2–4 years.

Cold Planing and Micro Milling

Also known as milling or profiling, this controlled removal process adjusts pavement depth to correct surface irregularities. Applicable across all PCI levels (1–100), cold planing and micro milling can serve preservation and rehabilitation purposes. Cold planing improves smoothness, and drainage, as well as mitigating issues like top-down cracking and raveling. It is effective for excavation, reconstruction, rehabilitation, and maintenance, helping extend pavement lifespan.

PCI Range: 55 – 69

As pavement deteriorates into lower PCI levels, preservation remains an option, however, treatments become more complex and costly, often approaching rehabilitation. Roads with PCI scores below 55 typically require structural repairs or reconstruction.

For roadways in the 55–69 PCI range, effective treatment options include:

Cold In-Place Recycling (CIR)

CIR is a cost-effective, long-lasting, and environmentally friendly alternative to traditional rehabilitation methods. This process cold mills and recycles the top 2–5 inches of asphalt using a continuous train operation. By fully reusing existing materials, CIR minimizes trucking, reduces construction time, and conserves natural resources, significantly lowering project costs. When combined with an appropriate surface treatment, cold in-place recycling can extend pavement life by 15–20 years.

Hot In-Place Recycling (HIR)

HIR is an on-site pavement preservation and corrective maintenance technique that, when paired with an asphalt overlay, can serve as structural rehabilitation. There are three HIR methods: surface recycling, remixing, and repaving. Each involves heating, softening, milling, mixing, placing, and compacting the existing pavement. Additives and rejuvenators can be included in the mix to enhance the recycled asphalt, improving durability. HIR is ideal when mill-and-fill or leveling is needed before an overlay. Depending on the extent of restoration, HIR can extend pavement life by 7–15 years.

The Science of Pavement Preservation: Selecting the Right Treatment

These are just a few pavement preservation techniques available to extend pavement lifespans. Along with an accurate PCI grade, selecting the most effective treatment depends on several key factors, including pavement composition (asphalt, concrete, or bituminous), environmental conditions, and traffic demands. For example, roads exposed to frequent freeze-thaw cycles, extreme heat, or severe weather may require specialized preservation strategies.

A successful pavement preservation plan starts with a thorough assessment of pavement conditions, identification of distress types, and accurate PCI scoring. Working with pavement management professionals, like the Transmap team, ensures informed decision-making and an effective preservation strategy.

Transmap is a nationwide provider of pavement, roadway, and asset management services for cities, counties, and municipalities. Using advanced technology, we deliver high-quality data analysis and exceptional customer service. Our commitment to accuracy and efficiency helps agencies maintain safe and reliable infrastructure while optimizing budgets.

To learn more, contact our main office in Columbus, OH at (614) 810–1235.