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Tarmacadam is a road surfacing material made by combining crushed stone, sand, and tar, 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 terms "tarmacadam" and tarmac are also used for a variety of other materials, including tar-grouted macadam, bituminous surface treatments and modern asphalt concrete.



Macadam roads pioneered by British engineer John Loudon McAdam in the 1820s [1] 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, England, patented "lava stone." [2] This method involved spreading tar on the subgrade, placing a typical macadam layer, and finally sealing the macadam with a mixture of tar and sand. 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, Edgar Purnell Hooley was walking in Denby, Derbyshire, 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 from the nearby furnaces to cover up the mess. [3] Hooley noticed this unintentional resurfacing had solidified the road, and there was no rutting and no dust. [3] Hooley's 1902 patent for tarmac involved mechanically mixing tar and aggregate before lay-down and then compacting the mixture with a steamroller. The tar was modified by adding small amounts of Portland cement, resin and pitch. [4] Nottingham's Radcliffe Road became the first tarmac road in the world. [3] In 1903 Hooley formed Tar Macadam Syndicate Ltd and registered tarmac as a trademark. [3]

Later developments

As petroleum production increased, the by-product bitumen 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 airports, [5] especially the apron near airport terminals, [6] although these areas are often made of concrete. Similarly in the UK, the word tarmac is much more commonly used by the public when referring to asphalt concrete.

See also

Related Research Articles

<span class="mw-page-title-main">Bitumen</span> Form of petroleum primarily used in road construction

Bitumen is a sticky, black, highly viscous liquid or semi-solid form of petroleum. In the U.S., it is commonly referred to as asphalt. 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 asphaltum was also used. The word is derived from the Ancient Greek ἄσφαλτος ásphaltos. The largest natural deposit of bitumen in the world, estimated to contain 10 million tons, is the Pitch Lake in southwest Trinidad.

<span class="mw-page-title-main">Road transport</span> Collective term for all forms of transport which takes place on roads

Road transport or road transportation is a type of transport using roads. Transport on roads can be roughly grouped into the transportation of goods and transportation of people. In many countries licensing requirements and safety regulations ensure a separation of the two industries. Movement along roads may be by bike, automobile, bus, truck, or by animal such as horse or oxen. Standard networks of roads were adopted by Romans, Persians, Aztec, and other early empires, and may be regarded as a feature of empires. Cargo may be transported by trucking companies, while passengers may be transported via mass transit. Commonly defined features of modern roads include defined lanes and signage. Various classes of road exist, from two-lane local roads with at-grade intersections to controlled-access highways with all cross traffic grade-separated.

<span class="mw-page-title-main">John Loudon McAdam</span> Scottish engineer and road-builder

John Loudon McAdam 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.

<span class="mw-page-title-main">Highway engineering</span> Civil engineering of roads, bridges, and tunnels

Highway engineering is an engineering discipline branching from civil engineering that involves the planning, design, construction, operation, and maintenance of roads, bridges, and tunnels to ensure safe and effective transportation of people and goods. Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance.

<span class="mw-page-title-main">Road surface</span> Road covered with durable surface material

A road surface, or pavement, 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, macadam, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.

<span class="mw-page-title-main">Asphalt concrete</span> Composite material used for paving

Asphalt concrete is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. Asphalt mixtures have been used in pavement construction since the beginning of the twentieth century. It consists of mineral aggregate bound together with bitumen, laid in layers, and compacted. The process was refined and enhanced by Belgian-American inventor Edward De Smedt.

<span class="mw-page-title-main">Macadam</span> Road building method by John Loudon McAdam

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 may form; it may also, after rolling, be covered with a cement or bituminous binder to keep dust and stones together. The method simplified what had been considered state-of-the-art at that point.

Edgar Purnell Hooley 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 became Tarmac Limited, one of the United Kingdom's largest building materials companies.

Pavement, in construction, is an outdoor floor or superficial surface covering. Paving materials include asphalt, concrete, stones such as flagstone, cobblestone, and setts, artificial stone, bricks, tiles, and sometimes wood. In landscape architecture, pavements are part of the hardscape and are used on sidewalks, road surfaces, patios, courtyards, etc.

Blacktop or asphalt concrete is a composite material used to surface roads. The word blacktop can also be used to refer directly to a paved road.

<span class="mw-page-title-main">Chipseal</span> Pavement surface treatment

Chipseal is a pavement surface treatment that combines one or more layer(s) of asphalt with one or more layer(s) of fine aggregate. In the United States, chipseals are typically used on rural roads carrying lower traffic volumes, and the process is often referred to as asphaltic surface treatment. This type of surface has a variety of other names including tar-seal or tarseal, tar and chip, sprayed seal or surface dressing.

<span class="mw-page-title-main">Stone mastic asphalt</span> Road construction material

Stone mastic asphalt (SMA), also called stone-matrix asphalt, was developed in Germany in the 1960s with the first SMA pavements being placed in 1968 near Kiel. It provides a deformation-resistant, durable surfacing material, suitable for heavily trafficked roads. SMA has found use in Europe, Australia, the United States, and Canada as a durable asphalt surfacing option for residential streets and highways. SMA has a high coarse aggregate content that interlocks to form a stone skeleton that resists permanent deformation. The stone skeleton is filled with a mastic of bitumen and filler to which fibres are added to provide adequate stability of bitumen and to prevent drainage of binder during transport and placement. Typical SMA composition consists of 70−80% coarse aggregate, 8−12% filler, 6.0−7.0% binder, and 0.3 per cent fibre.

The history of road transport started with the development of tracks by humans and their beasts of burden.

Tarmac Group Limited was a British building materials company headquartered in Wolverhampton, United Kingdom. It produced road surfacing and heavy building materials including aggregates, concrete, cement and lime, as well as operating as a road construction and maintenance subcontractor.

<span class="mw-page-title-main">Crushed stone</span>

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 is produced by natural processes of weathering and erosion and typically has a more rounded shape.

Concrete pavement restoration (CPR) together with concrete pavement preservation (CPP) is a group of various techniques used to maintain concrete roadways.

Diamond grinding is a pavement preservation technique that corrects a variety of surface imperfections on both concrete and asphalt concrete pavements. Most often utilized on concrete pavement, diamond grinding is typically performed in conjunction with other concrete pavement preservation (CPP) techniques such as road slab stabilization, full- and partial-depth repair, dowel bar retrofit, cross stitching longitudinal cracks or joints and joint and crack resealing. Diamond grinding restores rideability by removing surface irregularities caused during construction or through repeated traffic loading over time. The immediate effect of diamond grinding is a significant improvement in the smoothness of a pavement. Another important effect of diamond grinding is the considerable increase in surface macrotexture and consequent improvement in skid resistance, noise reduction and safety.

<span class="mw-page-title-main">Denby railway station</span> Former railway station in Derbyshire, England

Denby railway station was a railway station which served the village of Denby in Derbyshire, England. It was opened in 1856 as Smithy Houses by the Midland Railway to on its Ripley branch from Little Eaton Junction to Ripley.

<span class="mw-page-title-main">Pavement milling</span> Process in construction of removing at least part of the surface of a paved area

Pavement milling is the process of removing at least part of the surface of a paved area such as a road, bridge, or parking lot. Milling removes anywhere from just enough thickness to level and smooth the surface to a full depth removal. There are a number of different reasons for milling a paved area instead of simply repaving over the existing surface.

Tarmac may refer to:


  1. "Coloured Tarmacadam". www.colouredtarmacadam.co.uk. Retrieved 2020-11-25.
  2. From: 'Northern Millwall: Tooke Town', Survey of London: volumes 43 and 44: Poplar, Blackwall and Isle of Dogs (1994), pp. 423–433 Date accessed: 24 May 2009
  3. 1 2 3 4 "The man who invented Tarmac". BBC. 24 December 2016.
  4. Hooley, E. Purnell, U.S. Patent 765,975 , "Apparatus for the preparation of tar macadam", July 26, 1904
  5. "Tarmac, n". Oxford English Dictionary . Oxford University Press. June 2011.
  6. "Has tarmac become a generic trademark?". genericides.org. Retrieved February 17, 2021.