100 Degrees Cooler In Stockton

By Loren Faulkner | September 28, 2010

Most cities want to reduce their carbon footprint these days. Stockton (www.stocktongov.com), in the San Joaquin Valley of California, is no exception to the new enviro-friendly thinking. So, it teamed with George Reed Inc., a Central Valley paving contractor, to try a warm-mix asphalt technique rather than the traditional hot-mix procedure on a residential paving project recently.

A bit of research indicated the touted benefits of warm-mix asphalt technology by MeadWestvaco Corporation, an east coast company. Using a chemical additive called "Evotherm" it had developed, MeadWestvaco claims their warm-mix technology enables asphalt mixes to be produced at temperatures more than 100 degrees lower than traditional hot-mix asphalt applications. And that these lower production temperatures could reduce fuel consumption, greenhouse gas emissions and nitrogen oxides that lead to photochemical smog, plus a significant reduction in acid rain-causing sulfur dioxide. The technology is said to be odor free, reducing community response to ongoing road construction.

Warm vs. Hot-Mix

Dropping a temperature of over 300 degrees Fahrenheit, down to about 204 degrees or less, is significant. Apparently, the city of Stockton liked the warm-mix technology.

"We are very pleased with the successful results of this project," said Gordon McKay, deputy public works director - operations and maintenance for Stockton, in a press release. "This is the first time we have tried warm-mix asphalt in Stockton. It is a next-generation technology that produces durable roads while significantly reducing the environmental impact of construction on our community, something that we are striving to do as part of Mayor Chavez's commitment to the U.S. Mayors Climate Protection Agreement of 2005."


Questions for MeadWestvaco Specialty Chemicals

  • Is the warm-mix procedure much different than the hot-mix procedure for paving contractors?
    No, Evotherm was developed in the United States and is completely compatible with SHRP Superpave pavement designs. The aggregates and asphalts used with our warm mix are the same as those used for traditional mixes. Producing Evotherm requires little to no plant modifications, and our technology is paved using conventional paving equipment.
  • Are you finding a lot of interest in its use within California and Hawaii?
    CalTrans has been evaluating Evotherm and other warm mix asphalt technologies since 2006. While we are just starting to bring this innovative technology to California and Hawaii, we have several projects planned and are finding tremendous interest in producing high quality pavements that offer great life-cycle and environmental benefits. The opportunity to reduce paving temperatures by as much as 100 degrees Fahrenheit and dramatically reduce fuel consumption and emissions has been well received by many communities. We see warm mix technologies such as Evotherm as a great fit for both California and Hawaii.
  • How long has Evotherm been on the market?
    Evotherm was first developed in 2003. Since that time we have participated on over 50 projects globally. Working in the U.S., Canada, Mexico, China, Europe, and South Africa, our warm mix additives are generating a lot of interest around the world.
  • Do you have a list of other cities within California and Hawaii that are using Evotherm?
    To date we have participated in projects in Stockton, Escondido and in Orange County. Also, CalTrans and UC Davis are conducting heavy vehicle simulator testing of our warm mix technology in Watsonville. The test sections have been in place since August of this year, and we expect the results of the Evotherm performance along with two other technologies to be reported in early 2008. In addition to future work throughout California, we also have two projects planned in Hawaii that we should be completing by year's end.