Researcher Creates Used Cooking Oil-based ‘Bioasphalt’ By Becky Phillips Washington State University Over the past century, asphalt has played an integral role in the American economy, keeping citizens connected through a sprawling, easily accessible web of national roadways. Now, thanks to a researcher at Washington State University (WSU), the familiar fossil fuelbased product is going green. Haifang Wen, assistant professor of civil engineering in the WSU Department of Civil and Environmental Engineering, has developed a technology to substitute restaurant cooking oil for the crude oil traditionally used in the production of asphalt, creating a sustainable bioasphalt that looks and handles just like its petroleum-based counterpart. In the near future, Washington motorists may be the first in the nation to drive on streets and highways paved with waste cooking oil-based asphalt. “We are shooting for summer 2014 to construct a trial road – probably at least a quarter mile long,” Wen said. Faced with increasing petroleum prices, environmental regulations, and changes to the crude oil refining process, asphalt has become a costly commodity. Asphalt is currently made from the residue left behind after production of gasoline, plastics, and other materials, and still commands $700 to $800 per ton, or half the price of gasoline at $1,500 per ton, Wen estimates. “Every year in the United States, we use about 30 million tons of asphalt binder for roads, more if you include roofing shingles,” Wen noted. “It’s easily a multi-billion dollar business.” A business that will need to make inroads into an industry that hasn’t changed much over the years. “Only in the last decade has the green asphalt industry started coming together,” Wen commented. “It’s slowly picking up – more slowly than I wish.” In Iowa, for example, scientists are making a corn-based bioasphalt from residue left after the production of ethanol. In North Carolina, swine manure is being incorporated as a paving substitute. “Building roads is a big investment in taxpayer money,” said Wen. “In general, a one-mile road in a rural area costs at least a million dollars to build. With the waste cooking oil technology, we can reduce the cost of asphalt binder to under $200 per ton, making road building much cheaper.” Asphalt binder, the sticky “glue” that holds crushed stone and sand together to form pavement, only accounts for about five percent of the final hot mix asphalt (HMA) that is steamrolled into glossy new lanes and boulevards. HMA has to be tough and reliable, able to withstand the ravages of heavy trucks as well as the extremes of Mother Nature. In Wen’s lab, each component of his bioasphalt is subjected to a series of rigorous stress tests, such as intense heat, freezing temperatures, compression, and loading. After four years working with a chemist, Wen said the industry is eagerly awaiting the rollout of his product. R www.rendermagazine.com Render April 2014 49
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