Roman cement

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Above the ornate south doorway of Lichfield Cathedral stand seven figures carved in Roman cement. The South Door of Lichfield Cathedral - geograph.org.uk - 1640308.jpg
Above the ornate south doorway of Lichfield Cathedral stand seven figures carved in Roman cement.

Roman cement is a substance developed by James Parker in the 1780s, being patented in 1796. [1] [2]

Contents

The name is misleading, as it is nothing like any material used by the Romans, but was a "natural cement" made by burning septaria – nodules that are found in certain clay deposits, and that contain both clay minerals and calcium carbonate. The burnt nodules were ground to a fine powder. This product, made into a mortar with sand, set in 5–15 minutes. [1] [2] [3] The success of Roman cement led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk. [1] [4] [5]

History

There has been recent resurgence of interest in natural cements and Roman cements due mainly to the need for repair of façades done in this material in the 19th century. The major confusion involved for many people in this subject is the terminology used. Roman cement was originally the name given, by Parker, to the cement he patented which is a natural cement (i.e. it is a marl, or limestone containing integral clay, dug out of the ground, burnt and ground to a fine powder). [2] [5]

In 1791, Parker was granted a patent "Method of Burning bricks, Tiles, Chalk". His second patent in 1796 "A certain Cement or Terras to be used in Aquatic and other Buildings and Stucco Work", [1] covers Roman cement, the term he used in a 1798 pamphlet advertising his cement. He set up his manufacturing plant on Northfleetcreek, Kent. [2] It was notably patented late on but James Parker is still the subject of all the credit.

Later, in the 1800s various sources of the correct type of marl, known also as cement stone, were discovered across Europe and so there were a range of natural cements (with varying properties) in use across Europe. [2] [5]

An Austrian standard from 1880, providing a contemporary definition of Roman cements, reads: "Roman cements are products obtained from argillaceous marlstones by burning below the sintering temperature. They do not slake in contact with water and must therefore be ground to a floury fineness." [footnote 1] [3]

From around 1807 a number of people looked to make artificial versions of this cement (or more strictly hydraulic lime as it was not burnt at fusion temperatures). Amongst these were James Frost who had about twenty patents from 1811 to 1822 including one for "British Cement" and in 1824 Joseph Aspdin, a British bricklayer from Leeds, with his now famous patent for a method of making a cement he called "Portland cement". [6] This was done by adding various materials together to make an artificial version of natural cement. The name "Portland cement" is also recorded in a directory published in 1823 being associated with William Lockwood, Dave Stewart, and possibly others. [2] [5] [7]

The Alamo Portland and Roman Cement Works, in Brackenridge Park, San Antonio, Texas, United States Alamo cement works 2011.jpg
The Alamo Portland and Roman Cement Works, in Brackenridge Park, San Antonio, Texas, United States

There then followed a number of independently discovered or copied versions of this "Portland cement" (also referred to as proto-Portland cement). Proto-Portland cement had a different chemical makeup from other natural cements being produced at the same time: It was burnt at a higher temperature than other Natural cements and thus crosses the barrier between traditional vertical kiln fired natural cement and the later horizontal kiln fired artificial cements. This cement is not, however, the same as the modern ordinary Portland cement, which can be defined as artificial cement. [5]

James Frost is reported to have erected a manufactory for making of an artificial cement in 1826. [8] In 1843, Aspdin's son William improved their cement, which was initially called "Patent Portland cement," although he had no patent. In 1848, William Aspdin further improved his cement and in 1853, he moved to Germany where he was involved in cement making. [7] William Aspdin made what could be called meso-Portland cement (a mix of Portland cement and hydraulic lime). [5] [9]

Development in the 1860s of rotating horizontal kiln technology brought dramatic changes in properties, arguably resulting in modern cement. [5] Certainly it is difficult to define whether an old render was a natural cement (single source marl) or an artificial one, but there is no doubt as whether the cement was fired in a vertical or horizontal kiln. The names natural cement or Roman cement then defines a cement coming from a single source rock. Early or proto-Portland cement could be used for early cement that comes from a number of sourced and mixed materials. [5] There is no widely used terminology for these 19th-century cements. There had been, in order to rediscover this technology, two projects carried out by the European Union ROCEM and subsequently ROCARE [10] (an ongoing project). Both these only deal with natural cement - referred to as Roman cement without reference to the early artificial cements.

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<span class="mw-page-title-main">Portland cement</span> Binder used as basic ingredient of concrete

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 century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of portland cement are available. The most common, called ordinary portland cement (OPC), is grey, but white portland cement is also available. Its name is derived from its resemblance to Portland stone which is quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. His son William Aspdin is regarded as the inventor of "modern" portland cement due to his developments in the 1840s.

<span class="mw-page-title-main">Marl</span> Lime-rich mud or mudstone which contains variable amounts of clays and silt

Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae.

<span class="mw-page-title-main">Calcium oxide</span> Chemical compound of calcium

Calcium oxide, commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term lime connotes calcium-containing inorganic compounds, in which carbonates, oxides, and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate. By contrast, quicklime specifically applies to the single compound calcium oxide. Calcium oxide that survives processing without reacting in building products, such as cement, is called free lime.

<span class="mw-page-title-main">Lime kiln</span> Kiln used for the calcination of limestone

A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide). The chemical equation for this reaction is

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Mortar is a workable paste which hardens to bind building blocks such as stones, bricks, and concrete masonry units, to fill and seal the irregular gaps between them, spread the weight of them evenly, and sometimes to add decorative colors or patterns to masonry walls. In its broadest sense, mortar includes pitch, asphalt, and soft mud or clay, as those used between mud bricks, as well as cement mortar. The word "mortar" comes from Old French mortier, "builder's mortar, plaster; bowl for mixing." (13c.).

<span class="mw-page-title-main">Joseph Aspdin</span> English inventor of Portland cement (1778–1855)

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<span class="mw-page-title-main">Lime (material)</span> Calcium oxides and/or hydroxides

Lime is an inorganic material composed primarily of calcium oxides and hydroxides, usually calcium oxide and/or calcium hydroxide. It is also the name for calcium oxide which occurs as a product of coal-seam fires and in altered limestone xenoliths in volcanic ejecta. The International Mineralogical Association recognizes lime as a mineral with the chemical formula of CaO. The word lime originates with its earliest use as building mortar and has the sense of sticking or adhering.

<span class="mw-page-title-main">Hydraulic lime</span>

Hydraulic lime (HL) is a general term for calcium oxide, a variety of lime also called quicklime, that sets by hydration. This contrasts with calcium hydroxide, also called slaked lime or air lime that is used to make lime mortar, the other common type of lime mortar, which sets by carbonation (re-absorbing carbon dioxide (CO2) from the air). Hydraulic lime provides a faster initial set and higher compressive strength than air lime, and hydraulic lime will set in more extreme conditions, including under water.

<span class="mw-page-title-main">Lime mortar</span> Building material

Lime mortar or torching is a masonry mortar composed of lime and an aggregate such as sand, mixed with water. It is one of the oldest known types of mortar, used in ancient Rome and Greece, when it largely replaced the clay and gypsum mortars common to ancient Egyptian construction.

Metakaolin is the anhydrous calcined form of the clay mineral kaolinite. Rocks that are rich in kaolinite are known as china clay or kaolin, traditionally used in the manufacture of porcelain. The particle size of metakaolin is smaller than cement particles, but not as fine as silica fume.

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<span class="mw-page-title-main">Cement kiln</span> High temperature rotating oven used for producing clinker

Cement kilns are used for the pyroprocessing stage of manufacture of portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of cement are made per year, and cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant. As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, improvement of kiln efficiency has been the central concern of cement manufacturing technology. Emissions from cement kilns are a major source of greenhouse gas emissions, accounting for around 2.5% of non-natural carbon emissions worldwide.

<span class="mw-page-title-main">William Aspdin</span> English cement manufacturer/pioneer:Portland cement industry

William Aspdin was an English cement manufacturer, and a pioneer of the Portland cement industry. He is considered the inventor of "modern" Portland cement. He has also been termed "an incorrigible liar and swindler".

<span class="mw-page-title-main">Cement clinker</span> Main component of Portland cement

Cement clinker is a solid material produced in the manufacture of portland cement as an intermediary product. Clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter. It is produced by sintering limestone and aluminosilicate materials such as clay during the cement kiln stage.

<span class="mw-page-title-main">Cement mill</span>

A cement mill is the equipment used to grind the hard, nodular clinker from the cement kiln into the fine grey powder that is cement. Most cement is currently ground in ball mills and also vertical roller mills which are more effective than ball mills.

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

A raw mill is the equipment used to grind raw materials into "rawmix" during the manufacture of cement. Rawmix is then fed to a cement kiln, which transforms it into clinker, which is then ground to make cement in the cement mill. The raw milling stage of the process effectively defines the chemistry of the finished cement, and has a large effect upon the efficiency of the whole manufacturing process.

White Portland cement or white ordinary Portland cement (WOPC) is similar to ordinary, gray Portland cement in all aspects except for its high degree of whiteness. Obtaining this color requires substantial modifications to the method of manufacturing. It requires a much lower content in colored impurities in the raw materials used to produce clinker: low levels of Cr2O3, Mn2O3, and Fe2O3), but above all, a higher temperature is needed for the final sintering step in the cement kiln because of the higher melting point of the mix depleted in iron oxides. Because of this, the process is more energy demanding and the white cement is somewhat more expensive than the gray product.

James Frost (1780?-1840?) was an English businessman and inventor who invented processes that led to the eventual development of Portland cement.

References

Notes
  1. 1 2 3 4 "James Parker's Patent for "Roman Cement" in 1796 (Patent No 2120: granted 28 June, enrolled 27 July)". Cement Kilns. 28 June 1796. Retrieved 20 May 2013.
  2. 1 2 3 4 5 6 Roman Kozłowski; David Hughes; Johannes Weber (2010). "Roman cements - key materials of the built heritage of the nineteenth century". In M. Boştenaru Dan; R. Přikryl; Á. Török (eds.). Materials, Technologies and Practice in Historic Heritage Structures. Springer.
  3. 1 2 "Roman Cement - What is it?". IATCS - Institute of Art and Technology / Conservation Sciences, University of Applied Arts Vienna. Retrieved 2013-05-20.
  4. "What is Roman Cement?". Roman Cement, LLC. Retrieved 2013-05-20.
  5. 1 2 3 4 5 6 7 8 R. J. M. Sutherland; Dawm Humm; Mike Chrimes (2001). Historic Concrete: The Background to Appraisal. Thomas Telford. pp. 46–52. ISBN   978-0-7277-2875-3 . Retrieved 20 May 2013.
  6. Gillberg, B. Fagerlund, G. Jönsson, Å. Tillman, A-M. (1999). Betong och miljö[Concrete and environment] (in Swedish). Stockholm: AB Svensk Byggtjenst. ISBN   91-7332-906-1.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. 1 2 Francis, A.J. (1977). The Cement Industry 1796-1914: A History.
  8. Reid, Henry (1868). A practical treatise on the manufacture of Portland Cement. London: E. & F.N. Spon.
  9. Rayment, D. L. (1986). "The electron microprobe analysis of the C-S-H phases in a 136 year old cement paste". Cement and Concrete Research. 16 (3): 341–344. doi:10.1016/0008-8846(86)90109-2.
  10. "The EU-project ROCARE Roman Cements for Architectural Restoration to New High Standards". IATCS - Institute of Art and Technology / Conservation Sciences, University of Applied Arts Vienna. Retrieved 2013-05-20.
Bibliography
Footnotes
  1. modified in 1890: "Roman cements are products obtained from argillaceous marlstones by burning below the sintering temperature. They do not slake in contact with water and must therefore be ground to a floury fineness." It specifies the range of setting times which facilitated the choice of a suitable material for a given decorative task: "Roman cements bind fast, medium and slow. By fast binding cements one should understand those which with no addition of sand start to harden within 7 minutes from the moment water is added. Roman cement is considered a slow binding variety if hardening starts later than after 15 minutes."