Asphalt Trends

Trends in materials, methods shape industry as costs chip away at projects

By R. Carter Langston

As oil prices peaked above $75 per barrel in early July, this seasonal crude oil climb is hitting asphalt paving contractors and state departments of transportation hard. Costs for asphalt cement, an oil derivative, were up in May nearly 28 percent over the previous year. As costs spiral upward, officials in the Carolinas reported that revenues remained lower than anticipated.

"This seems to be the perfect storm," said Michael Covington, government affairs director with the South Carolina Department of Transportation. "Material costs are spiraling up and revenue is trending down."

The North Carolina Department of Transportation, which funds its highway projects through a combination of federal highway funding, state fuel surcharges and vehicle sales, reported in late June that it is pushing back projects a minimum of four months.

Congress passed a law in August 2005 that guaranteed each state at least 92 percent of what it contributes to the federal highway trust fund. But states now face a cutback in their spending authority based on tax revenue shortfalls.

Georgia and Florida, which have a more diversified transportation trust fund structure, aren't feeling the same pinch that the Carolinas face. Despite its revenue position, Florida is proceeding cautiously with its $3 billion projects because of the higher costs. The state legislature allows the transportation department to bid options and remove pieces of work to rein project costs. According to Brian Blanchard, director of construction with the Florida DOT, options helps the state maintain its commitments to local governments.

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Georgia, like many states, suspended its gas tax in September 2005, following the Hurricane Katrina-related gasoline price hike, but the state's DOT Commissioner Harold Linnenkohl reports that revenue is higher than his post-hurricane forecast.

And both of the Carolina's highway departments complain that costs are eroding productivity.

"In 2000, we were paving 10 mi. of road for the price that we're currently paving 6.1 mi. of road," Covington said.

"We're at a tipping point with the expense of building and maintaining transportation systems," said Christie Barbee, executive director of the Carolina Asphalt Pavement Association in Raleigh, N.C.

"Any eventual outcome will have a tremendous affect on the asphalt industry," she said. "The need and cost (of building and maintaining our highways) is exceeding our current revenue sources."

According to the July 3 issue of Engineering News-Record, the price for PG-58 paving asphalt increased 2 percent in July on the heels of three consecutive increases in April, May and June. While crude oil prices hovered around $70 per barrel, asphalt prices spiked 10 percent in June after 4.8 percent and 5.3 percent bumps in May and April.

While price volatility seems to be hitting the entire construction sector with increases also noted in steel and concrete costs, asphalt remains principally tied to the crude oil index. Asphalt cement, which is a distilled crude oil byproduct that binds the aggregate, represents 5 percent of the material mix in roads.

Asphalt Trends

There are a number of innovative paving approaches gaining attention in the industry, including warm-mix, open-graded friction course and porous asphalt applications. Open-graded and porous asphalt feature open surface spaces that allow water to penetrate for better managed storm water runoff.

And warm mix asphalt remains among the industry's hottest topic. But it's getting a cool test-and-see reception in the Southeast, where there is a longer paving season and no urgent requirement for reduced emissions outside the urban areas that are struggling to meet the EPA's air quality attainment standards.

According to Margaret Cervarich, vice president of marketing and public affairs for the National Asphalt Pavement Association in Lanham, Md., warm-mix asphalt continues to gain some traction among highway departments, particularly for its promise to extend the paving season.

"It's easier to get density with warm mix asphalt, so some of the states in colder climate zones like Virginia might be particularly interested in the process," Cervarich said.

Among other benefits that Cervarich cites are its reduced energy requirements. Warm mix requires 220-degree to 270-degree temperatures, compared to the 320-degree mix requirements for hot-mix asphalt. Less energy produces fewer emissions, which is particularly useful in metropolitan areas where EPA mandated air quality attainment is an issue.

Further, the warm mix process uses synthetic minerals, which act as a binding agent at lower temperatures. But don't assume that the synthetic binder additive reduces the amount of asphalt cement. Brian Prowell, assistant director of the National Center for Asphalt Technology, is recommending that asphalt cement be used at the same level as in hot-mix applications. The energy savings is proven, he said.

"McAsphalt in Ontario reported that one trial produced up to a 55 percent fuel oil savings," said Prowell. "Fuel reduction is a given with warm mix applications, but the cost of synthetics and other warm mix materials might zero out any overall cost savings at this point."

Florida tested a strip of warm mix last year along the Florida Turnpike in Orlando. The Florida test involved a strip of open-graded friction course, which allows storm water to permeate the top layer of pavement and roll off the impermeable under layer away from motorists. The state continues to evaluate the test and all of the state agencies remain concerned about reported moisture susceptibility issues, which can lead to stripping of the asphalt from the aggregate.

"At the moment, we're looking at the warm mix application primarily from an engineering perspective, rather than an emissions or total cost perspective," said Jim Musselman, with the Florida DOT.

South Carolina will begin its first warm mix test in Charleston when cooler temperatures return this fall.

Another paving trend expected to continue through South Carolina, Georgia and Florida is open graded friction course. All three states anticipate adding more miles of OGFC along primary roads. In fact, South Carolina is adding OGFC to 106 lane miles in two projects along Interstates 20 and 26 in the Upstate Region.

The project is one of the biggest current asphalt paving jobs in the state, said Danny Shealy, the director of construction for SCDOT. An 18-mi. stretch of I-26 involves all four lanes. The project cost is $16 million and Sloan Construction is the general contractor. Completion is scheduled for September. A 17-mi. stretch of I-20 involves only two eastbound lanes. The project cost is $7.5 million and Rea Construction is the general contractor. Completion is scheduled for October 2006.

"OGFC is not a commonly recognized name, but people sure recognize the difference in the rain," Covington said. "Especially going from a sealed pavement to OGFC in the rain, drivers immediately notice less road spray, improved visibility and more traction."

According to Barbee and a resident engineer, North Carolina experienced some maintenance challenges with a previous OGFC specification about 20 years ago, and the state has not adopted the design for statewide implementation. North Carolina recently resurfaced a stretch of 80 lane miles along Interstate 95 with OGFC asphalt.

"Clearly, North Carolina could be doing more of it," Barbee said. "The North Carolina climate is similar to that of Georgia and South Carolina, where OGFC has performed well."

Similar to the OGFC, porous asphalt parking lots feature voids that allow storm water to filter through the asphalt top layer and percolate through layered beds of stone and sand, back into the soil. Porous asphalt eliminates the requirement for retaining ponds, Cervarich said, and remains most popular in urban parking lot applications.

Aside from the benefit of eliminating costly and obtrusive retention ponds, porous asphalt parking lots lend to U.S. Green Building Council credits for Leadership in Energy and Environmental Design. Asphalt alone, which is the most recycled material product in the United States, receives one LEED credit, according to Cervarich. Based on parking lot specs, a porous lot can bring up to seven credits.

Cervarich said that recent changes in the EPA's storm water regulations and the U.S. Green Building Council have prompted interest among consulting engineers and public works departments.

As contractors and owners continue through this perfect storm of escalating costs and declining revenues, both groups remain interested in the innovative solutions to the continuing challenges associated with balancing growth and environmental stewardship. And - albeit at a slower pace - work continues on building and maintaining the Southeast's highways.