Tarmacadam is a

road surfacing A road surface (British English), or pavement (American English), is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, hoggin, cobbles ...

material made by combining

crushed stone Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers. It is distinct from naturally occurring gravel, which i ...

tar Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bit ...

, and

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

, patented by Welsh inventor

Edgar Purnell Hooley Edgar Purnell Hooley (5 June 1860 – 26 January 1942) was a Welsh inventor. After inventing tarmac in 1902, he founded Tar Macadam Syndicate Ltd the following year and registered tarmac as a trademark. Following a merger in 2013 the business bec ...

in 1902. It is a more durable and dust-free enhancement of simple compacted stone

macadam Macadam is a type of road construction, pioneered by Scottish engineer John Loudon McAdam around 1820, in which crushed stone is placed in shallow, convex layers and compacted thoroughly. A binding layer of stone dust (crushed stone from the o ...

surfaces invented by Scottish engineer

John Loudon McAdam John Loudon McAdam (23 September 1756 – 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 m ...

in the early 1800s. The terms "tarmacadam" and tarmac are also used for a variety of other materials, including tar-

grout Grout is a dense fluid which hardens to fill gaps or used as reinforcement in existing structures. Grout is generally a mixture of water, cement and sand, and is employed in pressure grouting, embedding rebar in masonry walls, connecting secti ...

ed macadam, bituminous surface treatments and modern

asphalt concrete Asphalt concrete (commonly called asphalt, blacktop, or pavement in North America, and tarmac, bitumen macadam, or rolled asphalt in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface roads, parkin ...

Origins

Macadam Macadam is a type of road construction, pioneered by Scottish engineer John Loudon McAdam around 1820, in which crushed stone is placed in shallow, convex layers and compacted thoroughly. A binding layer of stone dust (crushed stone from the o ...

roads pioneered by British engineer

in the 1820s are prone to rutting and generating dust. Methods to stabilise macadam surfaces with tar date back to at least 1834 when John Henry Cassell, operating from ''Cassell's Patent Lava Stone Works'' in

Millwall Millwall is a district on the western and southern side of the Isle of Dogs, in east London, England, in the London Borough of Tower Hamlets. It lies to the immediate south of Canary Wharf and Limehouse, north of Greenwich and Deptford, east ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

, patented "lava stone". This method involved spreading tar on the

subgrade In transport engineering, subgrade is the native material underneath a constructed road,http://www.highwaysmaintenance.com/drainage.htm The Idiots' Guide to Highways Maintenance ''highwaysmaintenence.com'' pavement or railway track (US: railroad ...

, placing a typical macadam layer, and finally sealing the macadam with a mixture of

and

. Tar-grouted macadam was in use well before 1900 and involved scarifying the surface of an existing macadam pavement, spreading tar and re-compacting. Although the use of tar in road construction was known in the 19th century, it was little used and was not introduced on a large scale until the motorcar arrived on the scene in the early 20th century. In 1901,

was walking in

Denby Denby is a village in the England, English county of Derbyshire that is notable as the birthplace of John Flamsteed, England's first Astronomer Royal, and the location of the Denby Pottery Company. The population at the 2001 Census was 1,827, in ...

Derbyshire Derbyshire ( ) is a ceremonial county in the East Midlands, England. It includes much of the Peak District National Park, the southern end of the Pennine range of hills and part of the National Forest. It borders Greater Manchester to the nor ...

, when he noticed a smooth stretch of road close to an ironworks. He was informed that a barrel of tar had fallen onto the road and someone poured waste

slag Slag is a by-product of smelting (pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-prod ...

from the nearby furnaces to cover up the mess. Hooley noticed this unintentional resurfacing had solidified the road, and there was no rutting and no dust. Hooley's 1902

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...

for tarmac involved mechanically mixing tar and aggregate before lay-down and then compacting the mixture with a

steamroller A steamroller (or steam roller) is a form of road roller – a type of heavy construction machinery used for leveling surfaces, such as roads or airfields – that is powered by a steam engine. The leveling/flattening action is achieved through ...

. The tar was modified by adding small amounts of

Portland cement Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th c ...

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

and pitch.

Nottingham Nottingham ( , East Midlands English, locally ) is a city status in the United Kingdom, city and Unitary authorities of England, unitary authority area in Nottinghamshire, East Midlands, England. It is located north-west of London, south-east ...

's Radcliffe Road became the first tarmac road in the world. In 1903 Hooley formed Tar Macadam Syndicate Ltd and registered tarmac as a trademark.

Later developments

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

production increased, the by-product

bitumen Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...

became available in greater quantities and largely supplanted coal tar. The Macadam construction process quickly became obsolete because of its onerous and impractical manual labour required. The somewhat similar tar and chip method, also known as (bituminous) surface treatment (BST) or "chip-seal", remains popular. While the specific tarmac pavement is not common in some countries today, many people use the word to refer to generic paved areas at

airport An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface ...

s, especially the

apron An apron is a garment that is worn over other clothing to cover the front of the body. The word comes from old French ''napron'' meaning a small piece of cloth, however over time "a napron" became "an apron", through a linguistics process cal ...

near

airport terminal An airport terminal is a building at an airport where passengers transfer between ground transportation and the facilities that allow them to board and disembark from an Fixed-wing aircraft, aircraft. Within the terminal, passengers purchase ...

s, although these areas are often made of

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

. Similarly in the UK, the word ''tarmac'' is much more commonly used by the public when referring to

References

External links

* {{Road types Asphalt Brands that became generic English inventions Pavements

Origins

Later developments

See also

References

External links