LTAP Articles

In March 2012, Congressman Lloyd Doggett (D-Austin) introduced the Coal Tar Sealants Reduction Act of 2012 in the House of Representatives. Doggett wants to amend the Toxic Substances Control Act to prohibit the manufacture, processing, distribution in commerce, and use of coal tar sealants.

For years, airports maintenance engineers have used coal tar sealers for airport aprons and alleys because it effectively resisted jet fuel spills and oil-based spills. However, due to a different coefficient of thermal expansion for coal tar and asphalt, the coal tar tends to crack in two to three years. In addition, coal tar also contains polycyclic aromatic hydrocarbons, compounds identified by the Environmental Protection Agency as “probable human carcinogens” and toxic to aquatic life.

Now, there is fuel resistant asphalt (FRA) that is a viable alternative to coal tar sealers. FRA was first developed in the Netherlands and has been used at several international airports, including those in Kuala Lumpur, Malaysia in 1996, Cairo, Egypt in 1997 and Aden, Yemen in 1999. FRA was first used in the United States at La Guardia Airport in New York in 2002 and then as a fuel-resistant apron application at Boston’s Logan International Airport in 2004 and in 2005. FRA was also used successfully in 2006 at Charlotte Douglas International Airport in Charlotte, North Carolina.

Bob Sikes Airport in Florida became a pavement pioneer when it used a new fuel-resistant asphalt for a $1.8 million apron project it completed December 2011. According to the product’s developers, P-401-FR – or the “Crestview Mix,” as it’s now known – staves off pavement degradation by providing resistance to aircraft fuels, hydraulic fluids and petroleum oils. The new asphalt mix has also demonstrated high tolerance to rutting and shoving.

The contractor placed a P-401-FR fuel resistant hot mix asphalt surface course on the apron. The mix for the surface course included a 12.5 mm (1/2-inch) nominal maximum size aggregate with a PG 82-22 asphalt binder. The fuel-resistant asphalt surface was between 1.5 and 2 inches thick. The acceptance protocol for the surface course was 96 percent of maximum theoretical density. The project worked well due to four key factors:

• The mix design called for a fine aggregate so the mix would be tight.
• The highly modified binder together with the 2.5 percent design air voids made a dense and waterproof mix.
• The use of superfine aggregate in the mix made good compaction possible.
• Stringent compaction was required to ensure acceptance.

Dr. Bob Boyer, P.E., a leading authority on airport asphalt says that the significance of the fuel-resistant mix to the asphalt industry could be large. “We finally found an asphalt mix that satisfies the requirements of airport aprons. It won’t shrink and crack after a few years and it is safe for the environment and workers.”

The biggest challenge of the P-401-FR Crestview Mix was working with its stiffer consistency – specifically, putting it on the ground and getting the necessary compaction in the pavement before the asphalt cooled. Heavy-duty rollers were on standby, but were never needed because the mix went down better than anticipated.

Alternate bids were taken for the project at the Bob Sikes Airport. The bid included PG76-22 asphalt with a coal tar sealant. The alternate bid was to use PG82-22 Fuel-Resistant (FR) asphalt on the apron without a sealant. When the two bids were compared, the PG82-22 initial cost came in 19 dollars higher per ton than the PG76-22 with a coal tar sealant. Although the initial cost of the PG82-22 mix was higher, in the long run the apron would not have to be re-sealed several times and it would save the airport time and money.

It looks like the use of FRA is in our future. A draft of a new FAA P-601, which is essentially the P-401-FR used at Bob Sikes Airport, specification is in the review process. It may be another year or two before it is adopted by the FAA.

1The above article is a summary of following two articles:

1. Kanable, R. (July-August 2012). Bob Sikes Airport Installs New Fuel-Resistant Asphalt. Airport Improvement Magazine.

2. Davis, J. (February 22, 2012). Fuel-resistant asphalt makes airport pavements more spill-resistant. Asphalt, the Magazine of the Asphalt Institute.

Photographs are of the Bob Sikes Airport, courtesy of Airport Improvement Magazine

In September of this year, construction will start on what’s dubbed the H-1 Rehabilitation Project which includes repaving a 3.5-mile stretch between Ward Avenue and Middle Street. Stone Matrix Asphalt (SMA), a gap-graded hot mix asphalt (HMA), will be a used for the wearing surface. It is designed to maximize deformation (rutting) resistance and durability by using a structural basis of stone-on-stone contact and a modified asphalt binder.

In general, an asphalt binder is modified to achieve the following types of improvements:

• Lower stiffness (or viscosity) at the high temperatures associated with construction, which facilitates pumping of the liquid asphalt binder as well as mixing and compaction of HMA.
• Higher stiffness at high service temperatures, which reduces rutting and shoving.
• Lower stiffness and faster relaxation properties at low service temperatures, which reduces thermal cracking.
• Increased adhesion between the asphalt binder and the aggregate in the presence of moisture, which reduces the likelihood of stripping.
• Extend the pavement’s service life.

The modification of neat (unmodified) asphalt binder to enhance its performance characteristics has occurred in the United States for more than 50 years. In a recent survey of 20 experts representing 18 states, 70 percent responded that there is a definite benefit in using polymer-modified asphalt mixtures to extend the pavement’s service life. Nearly 60 percent of those experts also responded that the use of polymer-modified asphalt mixtures significantly reduced maintenance costs, but there has been insufficient performance data to quantify that benefit or enhancement.

The survey also indicated that the primary reason why users choose to use polymer-modified asphalt is to increase the mixture’s resistance to rutting. Secondary reasons are to increase resistance to thermal cracking and to increase durability of the mixture.

“It is important to note that while some user agencies have indicated a willingness to increase service life or reduce the risk of early distresses through the use of modified asphalt binders (and their higher initial construction costs), not all asphalt pavements need to be constructed using modified asphalt mixtures. Each project should be evaluated to determine if the environmental conditions, traffic loading, expected service life, and performance warrant the use of modified asphalt materials.”¹

There are several types of modifiers available such as elastomers, plastomers, crumb rubber, polyphosphoric acid (PPA), fibers, antistrips and extenders.

One of the most widely-used modifiers for asphalt pavement binders, and the one that will be used in Hawaii, is styrene-butadiene-styrene (SBS) polymer, a synthetic rubber granulate which is a thermoplastic elastomer that can be shaped by heat. This polymer technology was developed in the 1970s by Houston-based Kraton Performance Inc. Locally, the polymer and asphalt will be pre-blended at the Asphalt Hawaii Terminal and then transported to the asphalt plant. SBS modified binders for asphalt paving are less brittle in cold temperatures and less soft in hot temperatures than binders that are not modified.

Modified asphalt binder is tentatively scheduled for availability locally from the first half of 2014 for the production of SMA mixes as well as for other types of projects. The Department of Transportation, Airports Division, NAVFAC Hawaii, and U.S. Army Corps of Engineers are already considering modified asphalt binders for airfield pavements. Open-graded mixes, such as open-graded friction course (OGFC) and porous asphalt, which have been produced with neat asphalt binder, would benefit from the use of a modified asphalt binder.

For the right project, improvement to pavements with modified asphalt binders can soon be realized in Hawaii.

¹Asphalt Institute, The Asphalt Binder Handbook, Manual Series No. 26, 1st Edition (USA, 2011), 161.

What is a perpetual pavement?  In general, a perpetual pavement is designed to make at-depth distress unlikely. Therefore, when distresses do occur, they will initiate at the surface and propagate downward. This pattern of distress can then be corrected by periodic surface maintenance and renewal before it affects the bulk of the pavement structure.

Perpetual pavements use multiple layers of durable asphalt to produce a safe, smooth, long-lasting road. The pavement design begins with a strong, yet flexible bottom layer that resists tensile strain caused by traffic, and thus stops cracks from forming in the bottom of the pavement. A strong intermediate layer completes the permanent structural portion, and a final layer of rut-resistant asphalt pavement yields a surface that lasts many years before scheduled restoration.

Michael J. Kvach, executive director of the Asphalt Pavement Alliance (APA) says “Asphalt roads can be engineered to last indefinitely with only routine maintenance and periodic surface renewal.”

“The advantages of these Perpetual Pavements are significant. Life-cycle costs are lower because deep pavement repairs and reconstruction are avoided. User delays are reduced because minor surface rehabilitation requires shorter work windows and can be accomplished outside of peak traffic hours. And minimal rehabilitation, combined with recycling any materials that are removed from the pavement surface, reduces the amount of material resources required over the pavement’s life.”

Road in the Ewa by Gentry development constructed per the 2006 City standard.
(Courtesy of Google Earth)

In Hawaii, the City and County of Honolulu’s “Structural Design Requirements for New Asphalt Concrete Pavements”, which became effective in March 2006, is for long-lasting low-volume pavements. This new standard is getting us closer to the concept of perpetual pavements.  Prior to the change, the standard pavement section was a surface wearing course place directly on an aggregated base course.  The new standard requires a layer of asphalt treated base between these two layers, making it similar to the pavement structure described above.  The aggregate base course is the bottom layer, the asphalt treated base is the intermediate layer, and wearing course is the final layer.  In addition to the City’s 2006 standard, some of the pavement designs done per the State Department of Transportation design procedure will result in very thick pavements, which are close to those required by perpetual pavements.

Has the City’s new standard been effective?  It is too short a time frame to make an evaluation of the performance of the revised pavement structure.  However, roads in the Ewa by Gentry residential development that were constructed using the new standard do not show any signs of cracking or other distresses.  This is a positive indication that we may be on the right track to successful perpetual pavements.

The Florida Department of Transportation was the recipient of a 2012 Perpetual Pavement Award for a section of State Road 55/U.S. 19 in Levy County, from the Citrus County line to State Road 121.
(Courtesy of the Asphalt Institute)On the national level, the APA gives out annual awards to recognize and celebrate perpetual pavements.  The award is given to the state transportation department owners of asphalt pavements that are at least 35 years old and have never had a structural failure. The average interval between resurfacing of each winning pavement must be no less than 13 years. The road must demonstrate the characteristics expected from long-life asphalt pavements: excellence in design, quality in construction, and value for the traveling public.  Engineers at the National Center for Asphalt Technology (NCAT) evaluated the nominations for the Perpetual Pavement Award and a panel of industry experts validated the winners.

Perhaps one day, Hawaii will have an award winning road.

Conference registration

General and educational sessions, along with networking events attracted over 825 attendees to the National Asphalt Pavement Association (NAPA) 58th Annual Meeting at Scottsdale, Arizona on February 10 to 13. General Sessions covered the current legislative climate in Washington, D.C., and energy trends and their effect on asphalt supply. Educational breakout sessions covered everything from rubber- and polymer-modified binders, workplace safety, and pavement economics to public-private partnerships, marketing strategies, and high-RAP mixes.

There are two topics that I would like to highlight: NAPA’s Action Plan and Tough Time – Tough Decisions. 2013 NAPA Chairman of the Board John Keating gave an overview of NAPA’s three-part action plan.

Part 1 is the recently created the Pavement Economics Committee (PEC), which brings together representatives of NAPA and the State Asphalt Pavement Associations (SAPA). The PEC and its six NAPA-SAPA Task Groups committed nearly a $1 million in funding to a significant array of projects that have the potential to defend and improve the asphalt industry’s competitive position.

Part 2 is the research and support effort which is a combined effort of the National Center for Asphalt Technology (NCAT) and the Asphalt Pavement Alliance (APA). NCAT is the world class leader in asphalt research and capable of being our industry’s innovation resource. The APA is the deployment resource for our industry, recently launching the Asphalt FACTS (www.asphaltFACTS.com) campaign that reached over 1 million people online in the first month. In addition, the APA has an expert task force available to assist states with their marketing efforts.

Part 3 is to get our message to our customers. We need to package and brand our products in a language that resonates with each customer segment.

Keynote speaker Alison Levine

Keynote speaker Alison Levine spoke about tough times – tough decisions and the lessons learned as the leader of the first team of American women to conquer Mount Everest. The lessons learned can also be applied to businesses. For example, she learned to “do more with less” and to get the job done with the available resources. She had to evaluate what was happening at the moment and “adapt to an ever changing environment”. Her time on the mountain helped her to understand that it is important to “build relationships” before you need them and to “take prudent risks” by learning from people’s missteps. Most of all, she learned to “do whatever it takes” to survive. The ability to be creative and to not let fear stop you from doing what was required was a big part of the team’s success at reaching the summit.

An awards breakfast held on the last day of the meeting focused attention on The Shelly Company, a division of Oldcastle Materials Co., the winner of the Sheldon G. Hayes Award for Highest Quality in Asphalt Paving for its milling and overlay work on a stretch of 11.18 miles of I70, in Franklin County, Thornville, Ohio. The pavement on this four-lane interstate through central Ohio was cracked and deteriorating when the job began. The final product was a smooth, safe, and durable pavement. The project utilized two green paving technologies: Reclaimed Asphalt Pavement (RAP) and Warm Mix Asphalt (WMA). The company took the asphalt milled from the roadway (i.e. RAP) back to its plant where it was incorporated into all the asphalt mixes used on the project, reducing the need for virgin aggregate and asphalt binder for the project. Company crews worked at night to minimize traffic disruptions. By using WMA, the company achieved the desired pavement compaction and smoothness despite less-than-ideal nighttime temperaturTitle: Talk Story Timees.

The four-day meeting provided not only relevant educational topics, but also an opportunity to reconnect with old friends and make new ones as part of HAPI’s effort to promote our industry locally.

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Jon Young

The Hawaii Asphalt Paving Industry (HAPI) has appointed Jon Young, a civil engineer formerly with Belt Collins, as its full-time Executive Director. As Executive Director, Young will lead our industry’s efforts to raise awareness of best practices and the latest technologies available in asphalt paving to improve the condition of Hawaii’s roads and transportation infrastructure.

“From a government perspective, we’re always looking for resources to enhance our understanding of the latest technologies and best practices available. I’m looking forward to working with Jon to meet our island’s growing transportation needs,” said Wayne Y. Yoshioka, director of the City and County of Honolulu’s Department of Transportation Services.

“We’ve set some very ambitious goals for ourselves,” Young said. “It’s going to take a lot of work but we hope to get Hawaii to the point where our roads are ranked among the best in the country, built using sustainable practices and technologies.”

One of the sustainable technologies is reclaimed asphalt pavement (RAP), which uses recycled asphalt material. This product reduces waste that would otherwise burden local landfills without sacrificing quality. In fact, many other states and countries use this proven technology.

HAPI is also available to provide support for our customers’ efforts towards developing and maintaining pavement preservation programs, which extends the life of our roads. Our members—hot mix producers, asphalt suppliers, aggregate suppliers, laydown contractors, sealing and crack repair contractors, and engineers—provide services for all aspects of pavement preservation.

HAPI will continue to collect and disseminate technical data and guidelines, sponsor educational and technical seminars, and assist architects, engineers and contractors responsible for the design, construction and maintenance of asphalt pavements. Our office is conveniently located at 1287 Kalani Street, Suite 202, which is across the street from Young’s Fish Market. There is ample free parking in front of the building. Please feel free to stop the office or to contact Jon at 847-4274 or by email at jon@hawaiiasphalt.org.