It is made from a blend of crushed rock, rubber and polyurethane, a synthetic plastic that replaces bitumen as the binding agent and allows even bigger pores in the road surface.
In earlier testimony Friday, an FBI agent who looked through a window of Terry Nichols' garage and saw plastic barrels like those believed to have been used in the Oklahoma City bombing testified Friday that he thought the FBI had Nichols' consent to search his property.
Since plastic was first synthesized in the early 1900s, it has evolved into everything from lifesaving medical devices to a softening agent in hair conditioner.