VDOT Tests Show Standard Chip Seal and Microsurface Treatment Specs Hold Strong

The Virginia Transportation Research Council (VTRC) released a final report titled “Pavement Preservation Demonstration Projects for Chip Seal and Microsurfacing Treatments” based on research performed for the Virginia Department of Transportation (VDOT). VDOT prepared the field trial to assess how surface treatments are specified across the Commonwealth and beyond. The results show that sometimes sticking with the tried-and-true pays off.

The initiative stemmed from VDOT’s collaboration with the National Cooperative Highway Research Program (NCHRP), as part of project 20-44(26), and it built on guidance from earlier NCHRP 14-37 work. By 2021, three new specs focused on chip seal, microsurfacing and fog seal were crafted. These updates combined Virginia’s current practices with newer national guidelines developed by the American Association of State Highway and Transportation Officials (AASHTO).

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VDOT hit the field in 2022 with two real-world test projects: a chip seal job in Prince George County, and a microsurfacing treatment—alongside a fog seal on the shoulders—in York County’s Hampton Roads district.

The report from Ilker Boz, Ph.D., P.E., the senior research scientist, and Harikrishanan Nair, Ph.D., P.E., the associate director for pavements, is summarized herein.

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Two Treatments

For the chip seal trial, crews tackled a 3-mile stretch of Route 623. The section was divided into two parts: a 0.9-mile demo using the new specification, and a longer reference section done according to VDOT’s existing spec—a modified single-layer chip seal.

Meanwhile, on Route 132 in York County, the microsurfacing project took a similar approach. One direction of the road received the updated microsurfacing treatment, while the other direction received the standard treatment as a control. Both shoulders also received a fog seal treatment.

The roads selected for these trials represented typical traffic volumes for secondary and arterial roadways ranging from 450 to 750 vehicles per day in Prince George, and up to 10,000 vehicles per day in Hampton Roads.

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While the average motorist wouldn’t notice the difference, there were some technical changes baked into the new specs. They leaned on several AASHTO standards, such as M 340 and R 102 for chip seals, and M 341 and R 103 for microsurfacing.

These specs updated material properties, application rates, design procedures, and even quality control benchmarks. The goal was to improve performance, increase longevity and reduce maintenance needs.

VDOT wanted to know if the new guidelines would deliver a smoother ride, better skid resistance, or more durable surfaces than their current practice.

Embedment Proves Chip Seal Quality

Inside the Evaluation Process

Before construction began, crews documented the surface conditions using visual inspections and data-driven metrics. They measured everything from texture depth and rutting to overall ride quality.

Throughout construction, the team observed weather conditions, material application methods, and how closely crews followed both the old and new specs. After completion, both test sections were monitored for 13 months, using specialized tools, like VDOT’s pavement profiler and the SCRIM® machine, to measure macrotexture (mean profile depth), rut depth, friction and International Roughness Index (IRI).

Securing Sealing at Pennsylvania Avenue

Chip Seal Verdict: Room to Improve

The findings suggested the chip seal executed under the new specification didn’t perform any differently than the one done the old way. In fact, there were several challenges during construction of the demonstration section. Crews struggled to hit the target aggregate application rate. The spreading of the stone wasn’t as uniform as needed, which contributed to inconsistencies in surface texture and friction. There was also a notable difference in the structural approach—one section used a standard single-layer seal while the other employed a modified version.

Researchers concluded the performance differences were due more to these inconsistencies than the specs themselves. Boz and his team concluded that more field trials are needed, especially using the modified single-layer method under the new spec. Until then, VDOT’s current chip seal approach remains the standard.

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Microsurfacing Verdict: Hold Steady

The microsurfacing side of the study delivered a similar outcome. Despite applying the newly developed spec on one side of Route 132 and the existing spec on the other, researchers didn’t find any notable differences in short-term performance.

Skid resistance, surface texture and ride quality were comparable between the two sections. While the fog seal added a protective layer to the shoulders, its role wasn’t central to the comparative analysis.

Given these results, the recommendation was straightforward: VDOT should continue using its current microsurfacing spec. There’s no performance-based reason to switch at this time.

The demonstration projects weren’t failures, but provided valuable insights on how specification changes affect field performance, and more importantly, what it takes to implement them effectively. Even the best-designed specs won’t yield great results without precise application and construction quality. This was especially evident in the chip seal section, where variable stone coverage “hurt” the final outcome.

The study underscored the importance of training, consistency and real-time quality control in ensuring that new specs don’t just look good on paper, but work on the pavement too.

Lightweight Aggregate Used to Extend Asphalt Pavement Life

VDOT’s Next Steps

Based on the findings, researchers are recommending the following:

• More field trials using the new chip seal spec with modified single-layer design. This will help determine whether the spec itself or the execution was the limiting factor.
• Stick with current microsurfacing specs for now.
• Continue collecting data to better understand long-term performance trends beyond the initial 13-month observation window.

In the meantime, VDOT remains committed to innovation, but with a healthy dose of caution. The agency’s goal isn’t just to change specs for the sake of change, but to make sure every adjustment truly adds value for Virginia’s road users. Behind every resurfaced road or preserved shoulder is a mix of engineering standards and budget constraints to fit real-world conditions. For VDOT, this study was about asking the hard questions and being open to the answers—even when those answers suggest sticking with what already works.

For more information, read the full report from Virginia Transportation Research Council here.

High-altitude preservation with soy-based RePlay restores binder to 1.25 inches

At 6,200 feet at the gateway to the Yellowstone and Grand Teton National Parks, the pavements in the Town of Jackson face the pendulum of 90-degree summers and intense UV, to subzero winters and freeze-thaw conditions.

“Traditional fog seals give us a couple of years of color, but not real structural help,” explained Senior Engineer Scott Mohror, P.E. “We needed a treatment that actually puts binder back into the asphalt pavement, not just on top.”

The town turned to BioSpan Technologies’ RePlay® Agricultural-Oil Seal & Preservation Agent.

“RePlay soaks in deeper to replenish lost oils, bond with aging binder, and lift binder content,” explained Lindsey Hermes, president and COO of BioSpan Technologies. “That rebuilt flexibility keeps roads in service years longer.”

RePlay checked three boxes for the town:

• Deep penetration. Lab work later confirmed movement to 1¼ inches.
• Faster cure time, which is essential during summer tourist season.
• Carbon-negative profile that advances Jackson’s Net-Zero 2030 plan.

And they discovered an added bonus. According to Mohror, “It smells like aromatherapy—citronella and orange instead of hot [asphalt].” This novelty even drew a curious black bear to one freshly treated block.

Bargen Inc. sprayed the RePlay Agricultural-Oil Seal at a rate of 0.020 gallons per square yard. The product is transparent, offering a stainless application that allows pavement markings to remain visible.

How Crews Applied RePlay

During an August 2024 window of clear weather, applicator Bargen Inc., Mountain Lake, Minnesota, treated five residential streets—Lodgepole Lane, Rancher Street, Flat Creek Drive, Bar-Y Road and Simpson Avenue.

The equipment Bargen used alternated between a flatbed carrying a 16-foot adjustable spray boom and a Toro compact utility vehicle (CUV) with an 11-foot boom. Both BioSpan spray systems are computer-controlled; the pump output is automatically calibrated to truck speed, with GPS used as a backup to prevent over- or under-application.

For the application rate, Bargen averaged 0.020 gallons per square yard (≈ 96.8 gallons per acre), which is Bargen’s standard “2-0” rate for pavements that already contain relatively high virgin-oil content. The crew used a hand sprayer to test strips at curb, crown and turn radii, which sometimes told them to adjust the rate or allow extra cure time on dense, high-traffic edges.

To prepare the surface, crews took care to sweep the pavement so that nothing stood in the way of RePlay achieving maximum penetration. Because it is a clear product, there were no staining worries. RePlay cures transparent, so Bargen didn’t have to worry about cleaning up a mess afterwards where the spray met the concrete curb; overspray isn’t visually objectionable once it dries.

Bargen’s crew normally sprays at about 38 psi but lessens the intensity along sensitive edges to prevent misting and overspray.

Core-Sample Results Confirm Rejuvenation

• Lodgepole Lane (PCI 77, 25+ years old): RePlay increased binder content by 5.47% ¼ inch from the surface and 5.69% at 1 ¼ inches depth, showing a positive effect on aging asphalt.
• Flat Creek Drive (PCI 58, 15+ years old): Binder content increased 4.75% at ¼ inch and 5.31% at 1 ¼ inches.
• Rancher Street (2-3 years old): Binder content grew 6.13% at ¼ inch and 6.19% at 1 inch, demonstrating the efficiency of RePlay on newer streets as well.

The overall project average was a +5.9% binder increase across the five streets. Viscosity testing showed lower stiffness, indicating renewed flexibility before winter freeze.

We learned from this to validate with cores. Deep-core binder testing created hard data that won Public Works approval for expansion.

We also learned that surface preparation is an important best practice. A backpack-blower and spot sweeping helped ensure maximum penetration.

It’s also best practice to dial back nozzle pressure near curbs, houses and parked vehicles. Bargen’s crew normally sprays at about 38 psi but lessens the intensity along sensitive edges to prevent misting and overspray.

“RePlay didn’t just seal the surface—it restored binder through the top inch of pavement. That’s the metric that moves a preservation program from ‘nice idea’ to a budget line,” Mohror said.

Looking Ahead

Earlier in 2025, armed with core data and positive neighborhood feedback, the Town of Jackson brought Bargen back to apply RePlay to another 30,600 square yards of pavement.

With measurable binder gains, faster reopening and a net-negative carbon footprint, Jackson’s pilot positions soy-based RePlay as an essential tool for high-altitude municipalities striving for both fiscal prudence and environmental stewardship.

Jeff Davis is the communications manager for BioSpan Technologies, specializing in bio-based pavement solutions, infrastructure and sustainability.

January conference features preservation award for Wisconsin county’s proactive pavement work

Sheboygan County, Wisconsin, is the recipient of the 2024 FP2 Inc. James B. Sorenson Award for Excellence in Pavement Preservation for its proactive approach to emerging trends in preservation. The Sorenson Award recognizes superior pavement preservation practice, usually to a city, township, county or state agency.

With a population of more than 117,000, Sheboygan County is comprised of 28 municipalities and is located on the shore of Lake Michigan. The county manages more than 2,100 centerline miles.

The award was presented to Sheboygan County at the January 2025 Winter Highway Conference, conducted by the Wisconsin County Highway Association (WCHA). A highlight was a tribute to Sheboygan County by U.S. Rep. Glenn Grothman (R-Wis.).

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“On behalf of Sheboygan County, we’re humbled and honored to accept this award for pavement preservation,” said Bryan Olson, transportation director, Sheboygan County Transportation Department Highway Division, who also thanked the county board for its support. “In 2017, with the support of the local businesses, our county board implemented having some sales tax proceeds used for transportation. This was a key factor in helping our department continue our mission. In a time when budgets were tightening and material costs were on rise, through the sales tax, we were able to expand our paving program to include more pavement preservation programs.”

Sheboygan County, like many Wisconsin counties, had a robust chip sealing program for many years prior to an agreement with WisDOT. Bryan Olson, transportation director, Sheboygan County Transportation Department Highway Division, shared information and expertise with the area DOT maintenance specialist regarding a chip seal treatment for a 10,000-foot segment of STH 144. They achieved such good results that they chip sealed the remaining 5 miles of the road in 2023.

Multi Faceted Approach

Sheboygan County’s pavement preservation strategy is based on education and research, including a live traffic test track (Sheboygan County Operational Pavement Preservation Evaluation, or SCOPE), and participation in preservation efforts through the National Road Research Alliance (NRRA).

The county focuses on “pre-preservation” treatments like void-reducing asphalt membranes (VRAM) and penetrating asphalt emulsions to extend maintenance timelines. Additionally, the county addressed funding shortfalls by enacting a transportation tax nearly 10 years ago, leading to significant increases in pavement preservation activities.

Sheboygan County recognizes that funding streams, however innovative, will not keep pace with the standard 15-year pavement life cycles. With a stated goal of reaching a 30-year pavement life cycle, buying into the pavement preservation approach was required. “We have tried various preservation products on many of our paving projects and have formulated a process that we believe will take us to our goal of reaching a 30-year pavement life cycle,” Olson said.

By investing in a less expensive preservation treatment instead of investing in a new surface at year 15, agencies can use savings to complete the needed improvements on other roads. Since the county owns and manages roads “cradle to grave,” it has invested heavily in pre-preservation treatments including VRAM (approximately 15 miles in 2024 alone) as well as post-construction activities.

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Vertically Integrated

Sheboygan County, like many Wisconsin counties, had a robust chip sealing program for many years prior to an agreement with WisDOT. WisDOT did little regarding early-life preventive treatments leading up to the agreement. When it became clear to WisDOT that processes such as chip sealing were required to stretch budget dollars, Sheboygan County stepped up to offer expertise.

“I knew the asphalt overlay would last longer with the proper maintenance in the future,” Olson said. “I began to have conversations with our DOT area maintenance specialist and his supervisor about trying to chip seal a segment of STH 144. After meeting with them and showing them other completed chip sealing projects throughout the county, the DOT agreed in 2022 to chip seal a 10,000-foot segment of STH 144, which resulted in an outstanding outcome with the remaining 5 miles of road being chip sealed in 2023.”

Olson and his team also invest significant time and resources into working with local municipalities to improve pavement outcomes. Acting as a consultant to the local municipalities builds trust and removes an additional barrier between the public and the decision makers.

The amount of local municipal work completed by Sheboygan County has grown steadily since 2016, sometimes at rates of over 10% annually. Sheboygan County is an influential leader in regional preservation activities from the Interstate and state highways, to the county, down to the lowest volume township roads, a case study in vertically integrated pavement preservation.

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Success with Legislation

In 2016, leaders within Sheboygan County, including past transportation director Greg Schnell, submitted a proposal to the Sheboygan County Board of Supervisors for a 0.5% county sales tax to support transportation infrastructure needs within the county. A similar initiative was voted down twice before, once in 2004 and again in 2009.

By working with the local business community, local municipalities and taxpayers, the third time was the charm. County leadership took an important step to dedicate revenue generated from the sales tax to transportation only. The results are impressive. A portion of the tax is also shared directly with local municipalities ($1.6 million in 2023), which is put towards improving critical local infrastructure.

The tax revenues produce a more predictable revenue stream, allowing Sheboygan County to plan several years into the future with a higher level of confidence. In 2023, the county was able to budget chip sealing on 32 miles of road, which is more than a 200% increase from 2016 before the tax revenue was available.

Certification Marks New Era in Preservation

Centerline Rumble Strips

Wisconsin, like many states, is using centerline rumble strips (CLRS) at an increasing rate, and Sheboygan County sees this is likely to continue. Sheboygan County is an active participant in an ongoing research project funded by NRRA titled Materials-Based Methods to Improve Rumble Strip Durability. The project aims to identify materials that can be used to preserve the integrity of the CLRS from the time of construction.

Sheboygan County agreed to allow researchers to install two preservation treatments to a section of CTH LL the county had planned to rebuild in 2023. Although CLRS were not originally planned for CTH LL, an exaggerated S-curve running through the project made it a suitable candidate, and the county agreed. Construction took place in August and September 2023. Sections using VRAM were installed prior to paving the upper layer, and sections using a penetrating asphalt emulsion were applied after milling of the CLRS. Untreated control sections will allow the county and researchers to monitor performance with time.

During construction of the Sheboygan County Operational Pavement Preservation Evaluation (SCOPE), the county installed void-reducing asphalt membrane (VRAM) along one section and joint adhesive along another. All photos courtesy of FP2

Scope Research

In 2020 a 6-mile segment of a highway in southern Sheboygan County was budgeted for full reconstruction. Consulting with industry colleagues, the county decided to use the segment as a live-traffic, full-scale research section called the Sheboygan County Operational Pavement Preservation Evaluation (SCOPE). SCOPE is built from a concept similar to MnROAD or the NCAT Test Track, but SCOPE is uniquely focused on preservation at the county level.

By addressing common problem areas during construction, a pavement will age and exhibit distresses in a more consistent and predictable way. Longitudinal joints, for example, are commonly one of the first areas to exhibit distress. During construction of SCOPE, Sheboygan County installed VRAM along one section and joint adhesive along another. The benefits of these treatments were clear to the county, and VRAM has been used by the county every season since SCOPE.

“This proactive approach has led to better understanding of roadway stresses and how to better maintain our roadway infrastructure,” Olson said. “Using products such as VRAM, we are seeing the huge benefit of keeping our center seams together sealed from the opportunity of moisture seeping into the roadbed. Sealcoating our roads earlier is proving to help to combat the damaging effects that UV has on the roadway surfaces maintaining the structural integrity for the next 20-30 years.”

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Transparency Success Key

Transparency is key to Sheboygan County’s success. The county maintains an up-to-date web page with project and treatment information, including a printable summary of all paving, reconstruction and preservation work. The website prominently displays information about the 0.5% sales tax. For larger projects, the county holds public information meetings, inviting the public through direct mailings and local newspaper advertisements. During projects, portable message boards and clear signage keep the public informed about progress and important updates.

When asked what the greatest strength of the Sheboygan County Highway Division is, director Olson said, “It’s our dedicated team of like-minded, goal-oriented staff.” Olson continued that the best way to preserve and leverage this strength is “…by providing the staff with the tools and resources needed to produce and install a well-maintained road infrastructure.”

“Serving as vice president for AASHTO,” said outgoing WisDOT secretary Craig Thompson, “I see firsthand what [Wisconsin does] differently. The biggest key is the relationship that the 72 counties have with the state of Wisconsin, which is constantly being reinforced because of our routine maintenance agreements.

“Sheboygan County is truly a leader in its level of collaboration and innovation, which I can see firsthand from all my visits here,” Thompson said. “Every time I’m here, the quality of the roads really impresses me. Sheboygan County clearly values pavement preservation and invests in it, which is so important for our constituents. By spearheading new initiatives in the state, like its SCOPE program, the county sets an excellent example for the rest of our state.”

Adapted from the Spring 2025 issue of Pavement Preservation Journal.

Two technologies shine for Ohio micro surfacing of 15-year-old state park pavement preservation

Overseeing state park roads, the Ohio Department of Transportation (ODOT) is no stranger to innovative pavement preservation solutions. Maumee Bay State Park faces a climate with freeze-thaw cycles and additional moisture from lake proximity. Water can make its way into small voids and cracks in pavement, and when temperatures are below 32°F, this water freezes and expands, causing cracks to grow and compounding pavement deterioration. To combat these challenges, the park needs durable, weather-resistant pavement that does not require frequent, disruptive repairs.

How to Micro Surface

After assessing the park’s current pavement conditions, ODOT identified micro surfacing as an ideal treatment. This cost-effective technique not only provides a protective barrier against oxidation and moisture intrusion, but also creates a high-friction surface to enhance year-round safety.

Maumee Bay’s existing hot mix asphalt (HMA) surface course was still in decent condition and around 15 years old, making it a good candidate for micro surfacing. By choosing the right treatment at the right time for the right road, ODOT is maximizing the life they will get from their pavement.

Nestled along the scenic shores of Lake Erie, Maumee Bay State Park is one of Ohio’s most cherished outdoor retreats. Spanning over 1,336 acres, the park offers a blend of natural beauty and recreational facilities, including over 250 campsites. Each year, its network of roads and parking lots experiences high visitor traffic from a full calendar of activities ranging from fishing and boating to cross-country skiing and sledding. Maintaining durable, safe and accessible infrastructure is essential to the park’s continued success.

PPRA’s research has shown micro surfacing—when performed with best practices—consumes less energy and reduces greenhouse gas emissions by more than 44% compared to HMA resurfacing. If the pavement is in the right stage for this process, states can use taxpayer dollars efficiently and sustainably when selecting these alternative materials and methods.

Micro Surfacing Product Evaluation

In a unique approach, ODOT used the Maumee Bay project to evaluate Ergon Asphalt & Emulsions’ (Ergon’s) eFlex®, a highly polymer modified micro surfacing treatment. Asphalt Materials, Inc.’s (AMI’s) AMISEAL™ was placed as a control section.

ODOT State Asphalt Materials Engineer Eric Biehl said, “I heard about the eFlex® product at the National Pavement Preservation Conference in 2016, and ever since, wanted to do a job with it.”

Micro surfacing consists of polymer modified asphalt emulsion with fine aggregates, mineral fillers and other additives. Ergon’s eFlex has enhanced polymer modification, compared to traditional micro surfacing treatments. It is formulated for enhanced durability, including increased resistance to tearing and scuffing of the pavement. Meanwhile, AMISEAL micro surfacing is a more traditional formulation, known for its longevity and reliable performance.

Micromanage the Stockpile for Micro Surfacing Success

Successful Micro Surfacing Application

In October 2024, Pavement Maintenance Systems, LLC (PMS), now part of Evergreen Roadworks, placed close to 40,000 square yards of micro surfacing across eight roads and three parking lots at Maumee Bay State Park.

Prior to the application, cracks larger than 0.25-inch were sealed and the entire project received tack coat, providing a strong foundation for the surface treatment. The actual micro surfacing construction process involved mixing the materials within the paver’s pugmill mixing chamber and applying the mixture evenly across the pavement through a spreader box. This method ensures uniform coverage and a quick, efficient application.

The eFlex product was used on 80% of the project, while traditional micro surfacing, AMISEAL, covered the remaining 20% of the designated control section. Each product was placed at 22 pounds per square yard, approximately 0.25-inch thick. There was no discernable variation in the application or appearance of eFlex vs. AMISEAL.

Despite temperatures around 50°F, both emulsions set effectively. The mat began as a gray-brown color, but within an hour, the emulsions darkened—a visual cue that the mat had cured. The quick-setting nature of micro surfacing enabled PMS to complete the project swiftly, minimizing public disruption. As a final result, the pavement had a refreshed, uniform dark surface.

PPRA’s research has shown micro surfacing—when performed with best practices—consumes less energy and reduces greenhouse gas emissions by more than 44% compared to HMA resurfacing. If the pavement is in the right stage for this process, states can use taxpayer dollars efficiently and sustainably when selecting these alternative materials and methods.

Partnering with an Expert Team

Working with an experienced micro surfacing contractor proved instrumental in a successful process. PMS, with its extensive background in micro surfacing, ensured efficient and high-quality work. The on-site team included Chase Cornell (foreman) and Jason Cline (operator) with 20 and 25 years of experience laying micro respectively. PMS’s project manager Steve Willett was present to supervise the entire operation. Since 1988, PMS has been honing its micro surfacing process. In addition to the team’s collective decades of experience, keys to success include their commitment to safety, traffic control and excellent communication.

Also contributing to the project’s success were AMI’s Vince Venturella and Todd Thomas from the specialty products team. Jeff Dunn and Chris Hollenback from Heritage Research Group were present to perform additional quality control. Additionally, ODOT State Asphalt Materials Engineer Eric Biehl joined, as he initiated the introduction of eFlex to Ohio.

The micro surfacing technique not only provides a protective barrier against oxidation and moisture intrusion, but also creates a high-friction surface to enhance year-round safety.

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Embracing Advanced Technology for Better Results

Micro surfacing bonds with existing pavement to form a layer of protection from moisture and oxidation—two key factors that lead to pavement degradation. This protective layer also increases surface friction, which enhances driver and pedestrian safety, especially during the winter.

The inclusion of Ergon’s eFlex as a micro surfacing option is an example of ODOT’s commitment to exploring advanced material technology. With its enhanced polymer modification, eFlex has been proven to deliver a durable, long-lasting surface with few maintenance needs. With Maumee Bay as its proving ground, ODOT will continue assessing premium products for state-wide use.

Gaining attention in the neighboring state of Indiana, rapid penetrating emulsions (RPE) are another category of asphalt product designed to extend pavement life. RPE penetrates the road surfaces and then cures, sealing off access to air voids, and mitigating the harmful effects of moisture and oxidation. This innovative product, developed by Heritage Research Group, and available as AMIGUARD™ RPE through AMI, is another tool DOTs can leverage to enhance their road networks.

Tips to Solve Micro Surfacing Messes

Pavement preservation techniques like micro surfacing and RPE are designed to enhance the longevity of HMA, offering a more substantial method of managing pavement. As a complement to HMA, preservation treatments open the door for applicators to add new services to their toolkit. These services, in turn, allow agencies to stretch their budgets further.

While pavement preservation treatments like micro require an upfront investment, the return on that investment offers an extended life of paved surfaces. Biehl said, “Our normal micro surfacing mix lasts roughly 7-9 years on interstates and state routes, so I hope to see the same life, if not more, from eFlex.”

According to the Pavement Preservation and Recycling Alliance (PPRA), micro surfacing treatments reduce the life cycle costs of roadways by 25-45%, compared to HMA resurfacing. Overall, Maumee Bay State Park’s recent micro surfacing project demonstrates ODOT’s proactive approach to pavement management. By choosing high-quality materials, working with expert contractors and embracing innovative preservation techniques, ODOT has set a standard for long-lasting, sustainable pavement solutions that benefit both the environment and the community. The successful application of eFlex and AMISEAL at Maumee Bay will serve as a valuable reference for future pavement preservation projects across the Midwest.

Indefinite Delivery Indefinite Quantity for seal coating pavement preservation in residential Hawaiian project

In Hawaii, Indefinite Delivery/Indefinite Quantity (IDIQ) contracts are used by the city, Hawaii Department of Transportation (HDOT) and the military. G P Roadway Solutions (GPRS), Honolulu, performed seal coating in West Loch residential streets for the pavement preservation of streets as part of an IDIQ contract for the City and County of Honolulu, Department of Facility Maintenance. The project started in early January 2023 and was completed in late July 2024.

A seal coat provides a protective layer that shields the underlying pavement from the damaging effects of water, ultraviolet rays and oxidation. This helps in prolonging the lifespan of the pavement.

A challenge to overcome on this project was detritus on the pavement. To address leaves constantly falling on the ground while applying the seal coat, GPRS had a person with an air blower removing any debris prior to the application of the material. In the second photo, you can see the shadows from the trees on the beautiful, finished product.

Set It Up For Safety

Any time work is being done on an existing roadway, traffic control is going to be a major concern to the commuting public. GPRS used in-house traffic control to perform their roadway safety requirements. GPRS Traffic Control Division displays true professionalism when performing their tasks. They ensured the work zone was safe and secure for their personnel and the general public.

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GPRS deployed a two-person traffic control team to flag and control the roadways while they performed work. The work zone was secured by using advanced warning signs, safety cones, directional arrows and personnel controlling street traffic in both directions using stop/slow signs.

GPRS deployed a two-person traffic control team to flag and control the roadways while they performed work.

Seal in Definite Quality

Another IDIQ contract, begun in the summer of 2022, had cleaned and sealed cracks in the pavement, so the first step for GPRS on this project was to remove all existing pavement markings. They used an eradication machine to remove existing double yellow lines and stop bars.

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GPRS prepared each area of the project by installing BMPs, cleaning each area and taping off items such as maintenance holes. Once the preparation work was completed, they applied two coats of seal coat material for each area for maximum protection of the asphalt pavement.

A challenge to overcome on this project was detritus on the pavement. To address leaves constantly falling on the ground while applying the seal coat, GPRS had a person with an air blower removing any debris prior to the application of the material. In the second photo, you can see the shadows from the trees on the beautiful, finished product.

A seal coat machine was used to apply the material; a wand was also used. The size of the area determined the specific technique they used on each section of the project.

The roads had to be opened by 3:30 p.m., so GPRS took curing time of the seal coat material into consideration to ensure they could meet this requirement. Preservation is critical to maintain the integrity and functionality of asphalt pavement by preventing moisture from destroying the city’s roads. It is anticipated that the application of a seal coat will extend the lifespan of the asphalt pavement by five to seven years.

Once preparation work was completed, crew members used both a seal coat machine and a hand wand to apply two coats of material for each area for maximum protection of the asphalt pavement.

For the final step of the project, GPRS used a Thermo Striping Machine to re-apply the double yellow lines and stop bars, using Ennis Thermo material.

IDIQ BASICS

The website for United States Federal Contractor Registration (USFCR) provided a blog post explaining the basics of Indefinite Delivery/Indefinite Quantity (IDIQ) contracts, describing them as providing “for an indefinite quantity of supplies or services during a fixed period. They are ideal for situations where the exact quantities and delivery times are not known upfront, allowing for flexibility to meet varying needs.”

Among the key components of the IDIQ contract—base contract, task orders and ceiling limit—the task orders should protect contractors from having surprise responsibilities added to their to-do list during the contract’s life. Other benefits for contractors, listed on the USFCR blog, include:

• A steady or reliable workload;
• A reduction in paperwork and time spent on negotiating contract items; and
• Strengthened partnerships.

The West Loch and Ewa Villages residential development in Honolulu also benefited from the City and County of Honolulu’s IDIQ contract with Miller’s Paving LLC, Oahu, with work that began in 2022. Hawaii Asphalt Paving Industry (HAPI) Executive Director Jon Young wrote in the association’s August newsletter of the contractor’s success using a new Crack Pro 260 gravity flow machine for the sealing of cracks over hundreds of streets before the next phase of preservation: the seal coat project detailed in the adjacent article.

“Preserve” can be defined as to keep in good condition or to keep safe from harm; to prevent decay and maintain. Think about preserving or upkeeping your home’s exterior. Rather than tearing everything down and starting over, properly timed preservation techniques can help to keep your house looking like new and functioning properly and efficiently. Some of these techniques include painting or replacing the windows or the roof. Applying these treatments at the right time prevents costly repairs and even complete reconstruction.

Maintaining an asphalt pavement is like preserving your house. There are times you don’t have to do full reconstruction of the road or even mill off the surface of the pavement. There are treatments to extend the lifespan of the pavement, keeping it in good condition and safe for the driving public. Not only does this extend the life of the pavement, but it also benefits the bottom line. Roads are a capital investment. Maintaining them properly can save money and stretch a tight budget.

Simply stated, pavement preservation is applying the right treatment to the right place at the right time. An asphalt deterioration curve can help determine timing and treatment.

Surface preservation treatments are meant to delay the need for rehabilitation or milling of the structural asphalt. As the pavement moves from fair to poor condition, the treatments available to you must be more structural in nature. Figure 1 shows an asphalt deterioration curve with different treatments applied to the pavement as the condition deteriorates.

Pavement preservation treatments can be divided into four categories:

• Surface treatments
• Pre-treatments
• Recycling and reclamation
• Base treatments

Some common surface treatments are crack seal, rejuvenating fog seal, micro surfacing and thin lift HMA overlay. Let’s discuss those in some depth.

Crack Seal

Placement of material into existing cracks.

Crack filling is the placement of modified asphalt material into non-working cracks to prevent the infiltration of water and incompressible materials like gravel and sand. Routing and sawing is performed as needed to create a more uniform area for the filler allowing for better control and ensuring a proper seal to the existing pavement.

There are certain conditions that should exist for a pavement to be a good crack sealing candidate:

• New or recently rehabilitated surface
• Limited linear cracking
• Little or no secondary cracking
• Little or no raveling at crack face
• Good base support
• Limited structural deterioration

Cracks must be cleaned and dried prior to applying the filler or sealant. Having a dry road is even more important than the air or pavement temperature. It’s also important to keep the meter tank no less than ¾ full to maximize the effective melting point.

How to Crack Seal Right, Step By Step

Rejuvenating Fog Seal

Process of restoring chemical properties of the aged asphalt binder.

A rejuvenating fog seal or asphalt rejuvenation does not provide any structural improvement, rather it’s an emulsion that penetrates the top 3/8” of pavement restoring the aged asphalt binder. The effectiveness of the treatment is typically determined by the reduction of the binder viscosity. It is a “top of the curve” preventative maintenance and extends a typical pavement life by 3-5 years per treatment when applied at the right time.

Asphalt rejuvenation works by re-proportioning the aged fractions (asphaltenes) to the fluid portion (maltenes) of the asphalt binder. The maltene fraction gives the asphalt binder its flexibility. Asphaltenes effects the viscosity of the asphalt; as this fraction increases with age, the viscosity also increases making the pavement less pliable and prone to cracking. Thus, by restoring the maltene to asphaltene ratio like that of a new binder, the life of the pavement is extended. This process is not unlike a bowl of spaghetti (asphaltenes) with sauce (maltenes).

Over time the water in the sauce evaporates causing the sauce to dry out or age making it difficult to move or separate the spaghetti. Refreshing (rejuvenating) the sauce brings the bowl of pasta back to life, making it easier to separate the spaghetti noodles and move them around. Rejuvenation aims to restore the pavement’s flexibility and resistance to cracking.

MDOT, NCAT Show How to Place New Rejuvenating Fog Seal

Micro Surfacing

Surface treatment mixture of polymer-modified asphalt emulsion, mineral aggregate, water, and additives. The mixture is made and placed on a continuous basis by mixing the ingredients using specialized equipment.

The micro surfacing formulation is based on mix design parameters: resistance to raveling, lateral displacement and resistance to moisture damage. The emulsion plays a key part in micro surfacing. The wrong emulsion or an emulsion that doesn’t work well with the other components can cause issues such as long set times, durability, and delamination.

Remember that temperature, humidity, and wind conditions all affect emulsion break and cure times. If using a micro surface in combination with crack sealing, ensure crack sealing material is not excessive where it can be picked up by the paver tires and spreader box runners. Screen the material immediately prior to loading the mobile support unit so there is no possibility of contamination when re-handling the material. Treat vegetation with herbicide early to prevent it from returning after the project is completed.

Many agencies have reported ten years or more of service life when micro surfacing is installed on newer asphalt pavements in good condition. However, when used as a “band aid” or as a stop-gap measure on an asphalt pavement in marginal condition in order to delay rehabilitation/reconstruction, surface treatments including micro surfacing will have a shorter service life. Having the proper mix design for the micro surfacing is critical to ensure all materials work together. Some emulsion chemistries do not work with certain aggregate combinations, and some react poorly to excessive mineral filler.

How to Micro Surface

Thin Lift HMA Overlay

Applied thin layer (1.5 inches or less) of hot mix to the surface of the road.

Thin lift overlays can be used to extend the life of a pavement by sealing small cracks and providing a new riding surface. Overlays can be applied with or without milling, but the existing pavement must be in good condition since the overlay provides little additional structure. Thin lift overlays are available as conventional dense graded mix, open graded friction course (OGFC) and stone matrix asphalt (SMA).

Thin lift overlays improve ride quality and surface friction, correct surface defects, enhance appearance, seal the surface, and reduce splash and spray.

Regardless of the pavement preservation technique, quality control and quality assurance (QC/QA) are vital prior to, during, and after construction. Look at these three elements of the typical preservation project—the emulsion, the distributor truck, the aggregate.

Emulsion

• Certificate of Analysis (Manufacturer)
• QC Sampling and Testing
• Temperature

Distributor Truck

• Calibrate ➔ Quantity
• Proper Pressure, Spray and Coverage
• Speed

Aggregate

• Proper Certified Test Results
• Quality Control Results
• Mix Design

While the materials for HMA and pavement preservation treatments are the same (aggregates, liquid binder, emulsions), the equipment varies, and the material testing is different. In efforts to standardize the testing and material selection, the American Association of Highway and Transportation Officials (AASHTO) created an emulsion task force (ETF) in 2008. Material standards, design standards and construction guides have since been developed, and in a 2012 passage from the Moving Ahead for Progress in the 21^st Century (MAP-21), state DOTs could begin to use federal funds for pavement preservation.

This high level of confidence was only one benefit to the on-going AASHTO standardization efforts. Other benefits include educating the next generation of DOT staff and preservation crews and offering a consistent way to select materials, test and design. Constant collaboration and education will only further enhance the quality of the pavement preservation techniques, ultimately extending the life of our pavements.

Best Practices for Asphalt Overlays and Thin Lifts

The team at Asphalt Testing Solutions & Engineering LLC, Jacksonville, Florida, prepared this back-to-basics article for the AsphaltPro and PreservationPro audience.