Evotherm WMA
Evotherm
As California's energy costs grow, and new state emissions standards lay on the horizon for our industry, Warm-Mix Asphalt Technology soon could be adopted as a clear preference for asphalt producers and customers alike. On Sept 28, George Weir's Escondido Asphalt & Paving became the first company to use Mead MestVaco's EVOTHERM warm-mix asphalt technology on a California project. The City of Escondido contracted the paving project for a new 12,000-square-foot parking lot on W. Washington Avenue in its city, using approximately 250 tons of warm-mix asphalt produced in Weir's plant. EVOTHERM technology enables asphalt mixes to be produced and applied at temperatures more than 100 degrees lower than hot-mix applications. Lower temperature requirements during production enabled a reduction of 55% in fuel consumption, a 46% reduction in greenhouse gases, a 58% decrease in the nitrogen oxides that lead to photochemical smog, and an 81% drop in acid rain-causing sulfur dioxide, as measured in trials in Wisconsin, Missouri, and Texas. With optimum laydown and compaction temperatures around 160 degrees, this technology is also achieving a 40% overall reduction in job emissions.
"We've been doing stuff that's 100-year-old technology right now, and it has to change," said Weir. "With the price of natural gas and emissions being such a big deal, we have to change. It's like regular versus unleaded gas." During the paving project, which was attended by representatives of Caltrans, San Diego Association of Governments (SANDAG) and city council members, the city's paving contractor J.D. Paving laid hot mix asphalt side by side with the warm mix asphalt. Both batches followed a design calling for a more coarse, less dense mix the City of Escondido had specified, rather than the more conventional half-inch California Green Book Type C, due to the heavier traffic loads on this parking lot pavement. Following the compaction process both mixes met the 95% design standard, while nuclear gauge tests verified that the warm mix asphalt actually surpassed the compaction of hot mix by more than a percentage point, achieving close to 97% compaction. This was a successful trial for the City of Escondido, and for California," said Robert Perez of J.D. Paving, the paving contractor. "We are pleased to play a role, as we're always seeking ways to reduce fuel consumption, as it is an important element in our cost to deliver such projects to the public. The added benefit of reduced emissions is important to everyone in our local airshed."
City officials were pleased with the successful demonstration. "This is the first time Escondido has ever used warm-mix asphalt on one of our projects. This temporary fire station and its parking lot are vital to serving our citizens, and the use of warm mix asphalt technology can allow us to meet these needs while lessening the impact of construction on the environment," said Mayor Lori Holt Pfeiler. "We are pleased that our partnership with George Weir Asphalt, Western Emulsions, Valero, and MeadWestvaco Specialty Chemicals produced positive results, and we thank our partners for their cooperation."
Several different warm mix asphalt technologies have been developed and tested to date worldwide, some using waxes and foam additives to achieve the lower temperature benefits. Mead WestVaco's EVOTHERM is emerging as a front-runner, since it's a straight "plug-in" technology that doesn't require significant changes to the asphalt plant or the production process. Already, their warm-mix method has been used in countries around the globe, including South Africa and China. And industry representatives said they believe that the method will become commonplace in this country within the decade.
In addition to energy savings and emission-reduction benefits, warm-mix technology results in a longer life for the asphalt binder, as it has less opportunity to degrade due to reduced heat. The city expects a proportionately longer life of the pavement and decreased maintenance costs over the lifetime of the parking lot. "We're excited to be working with agencies in California to prove EVOTHERM as a viable alternative to traditional hot mix asphalt," said Jonathan MacIver, Asphalt Innovations business development manager with MeadWestvaco Specialty Chemicals.
"In our nation, the hot mix industry consumes the energy equivalent of 1 billion gallons of diesel fuel each year to produce asphalt for roads and parking lots. Our Warm Mix Technology offers the potential of cutting this number in half. Coupled with major reductions in emissions and longer lasting pavement, Evotherm offers tremendous value to the citizens whose tax dollars fund these project."
Those benefits are enough to offset a roughly 1 - 2 percent difference in total job cost represented by the additional emulsion product, according to Bob Koleas, president of Western Emulsions Inc., which produces the emulsified mix of asphalt and EVOTHERM in its Irwindale, California plant. Valero Marketing & Supply supplied Western with the liquid asphalt for the job. Koleas said that Western Emulsions is playing a significant role in introducing this new eco efficient technology in California.
"Asphalt emulsions have always been environmentally sound and safe construction materials that save on fuels and energy," he said. "Warm Mix technology such as EVOTHERM will bring cooler paving techniques to many sensitive areas in our communities saving us not only fuel and energy but needed environmental reductions in emissions and fumes around construction in and around our communities."
"It's the same asphalt, the same rock," Koleas continued. "The biggest difference is the way it's done is a lot cleaner and cuts the energy consumption and emissions in half." Because the product is mixed at lower temperatures, it loses heat slower. That, said Koleas, can allow trucks to haul loads greater distances before the mix becomes unusable, and companies can pour asphalt in cooler weather, when it is normally difficult. He added that could be especially beneficial for construction projects in California, in light of legislation that Gov. Arnold Schwarzenegger signed last week capping greenhouse emissions in the state. "Our state's legislative leaders, resource agencies, energy suppliers, and environmental organizations will be looking carefully at the opportunities offered by warm mix asphalt technology," he said.