Asphalt pavementIn 1870, Professor Edward J. de Smedt, was granted a U.S. patent for laying sheet asphalt pavement (U.S. Nos. 103,581 and -2). It was known as French asphalt pavement (where it was first laid in Paris in 1854). Mixing sand with natural asphalt is too stiff to work at suitable temperatures in the needed portions of about seven parts sand. Instead, he made a mix in ratio about 5 to 1, fluxed with certain petroleum oils and mineral particles, which was was easier to work with. On a graded road surface, a half-inch layer of hot sand is laid, topped with a one-inch layer of the hot asphalt and sand mix, and compacted with a hot roller. The process is repeated to build up a thicker road covering. On 29 Jul 1870, an experimental stretch of this type of asphalt pavement was laid in front of the City Hall, William Street, Newark, N.J.«[Image: Road crew laying asphalt for a new road in Florida, 1917.] |
