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Macadam is a type of road construction pioneered by Scottish engineer John Loudon McAdam c. 1820, in which crushed stone is placed in shallow, convex layers and compacted thoroughly. A binding layer of stone dust (crushed stone from the original material) may form; it may also, after rolling, be covered with a cement or bituminous binder to ...
John Loudon McAdam, 1830, National Gallery, London. John Loudon McAdam (23 September 1756 [1] – 26 November 1836) was a Scottish civil engineer and road-builder. He invented a new process, "macadamisation", for building roads with a smooth hard surface, using controlled materials of mixed particle size and predetermined structure, that would be more durable and less muddy than soil-based tracks.
Tarmacadam is a concrete road surfacing material made by combining tar and macadam (crushed stone and sand), patented by Welsh inventor Edgar Purnell Hooley in 1902. It is a more durable and dust-free enhancement of simple compacted stone macadam surfaces invented by Scottish engineer John Loudon McAdam in the early 19th century.
The road shown in the picture looks to be surfaced with "crusher fines" [1] while true macadam roads are covered with a layer of tessellated (nested and interlocked together by pressure and vibration) homogeneous rock, leaving voids which drain water into the base. The result looks something like this: PXL_20211005_212244099.jpg.
In 1911, Ridge Road was built as a 14-foot-wide (4.3 m) macadam road from the National Pike south to the Patuxent River. [11] [12] That same year, construction began from Henderson's Corner at Frederick Road north of Germantown to Davis Mill Road near Cedar Grove. [11] That segment was completed as a 14-foot-wide (4.3 m) macadam road in 1912. [12]
The first segment of modern MD 212 to be built as a modern road was Riggs Road from Washington to the Adelphi Mill, which was then known as the Riggs Mill. The 14-foot-wide (4.3 m) macadam road was built in two sections, the first one from Ager Road near the modern MD 410 intersection to Northwest Branch opposite the Riggs Mill by 1910.
During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word "tarmac", which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural ...
The base course or basecourse in pavements is a layer of material in an asphalt roadway, race track, riding arena, or sporting field. It is located under the surface layer consisting of the wearing course and sometimes an extra binder course. If there is a sub-base course, the base course is constructed directly above this layer.