Asphalt is usually made from the bottom of the barrel, the dregs of the oil refining process. But then along came the tar-sands and better technologies for refining heavy oil into gasoline, and the price has climbed. It has gotten so expensive that rural roads are going back to the Stone Age.
But Chris Williams of Iowa State University has come up with an interesting alternative. He has cooked up a bio-oil from plants and trees that can replace the asphalt glue that holds our pavement together — Bioasphalt.
It’s made by fast pyrolysis — “the rapid thermal decomposition of carbonaceous organic matter in the absence of oxygen.” Science Daily explains:
Bio-oil is created by a thermochemical process called fast pyrolysis. Corn stalks, wood wastes or other types of biomass are quickly heated without oxygen. The process produces a liquid bio-oil that can be used to manufacture fuels, chemicals and asphalt plus a solid product called biochar that can be used to enrich soils and remove greenhouses gases from the atmosphere.
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