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 mid 19th century, and usually originates 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 similarity to Portland stone which was quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. However, his son William Aspdin is regarded as the inventor of "modern" Portland cement due to his developments in the 1840s.[1]

Portland cement is caustic, so it can cause chemical burns.[2] The powder can cause irritation or, with severe exposure, lung cancer, and can contain some hazardous components, such as crystalline silica and hexavalent chromium. Environmental concerns are the high energy consumption required to mine, manufacture, and transport the cement, and the related air pollution, including the release of greenhouse gases (e.g., carbon dioxide), dioxin, NOx, SO2, and particulates. The production of Portland cement contributes to about 10% of world carbon dioxide emission.[3] To meet the rising global population, the International Energy Agency estimated that the cement production is set to increase between 12 to 23% by 2050.[4] There are several ongoing researches targeting a suitable replacement of Portland cement by supplementary cementitious materials.[5]

The low cost and widespread availability of the limestone, shales, and other naturally-occurring materials used in Portland cement make it one of the lowest-cost materials widely used over the last century. Concrete produced from Portland cement is one of the world's most versatile construction materials.

Portland Cement Bags
Multiple bags of Portland cement wrapped and stacked on a pallet.
BlueCircleSouthernCementBerrimaNSW
Blue Circle Southern Cement works near Berrima, New South Wales, Australia.

History

Joseph Aspdin plaque 7 Sep 2017
Plaque in Leeds commemorating Joseph Aspdin
William Aspdin Radford cyclopedia Volume 1
William Aspdin is considered the inventor of "modern" Portland cement.[1]
2014-06-12 10 38 10 Fresh sidewalk along U.S. Route 95 (West Winnemucca Boulevard) near Melarkey Street and Nevada State Route 289 (Winnemucca Boulevard) in Winnemucca, Nevada
Freshly laid concrete

Portland cement was developed from natural cements made in Britain beginning in the middle of the 18th century. Its name is derived from its similarity to Portland stone, a type of building stone quarried on the Isle of Portland in Dorset, England.[6]

The development of modern Portland cement (sometimes called ordinary or normal Portland cement) began in 1756, when John Smeaton experimented with combinations of different limestones and additives, including trass and pozzolanas, relating to the planned construction of a lighthouse,[7] now known as Smeaton's Tower. In the late 18th century, Roman cement was developed and patented in 1796 by James Parker.[8] Roman cement quickly became popular, but was largely replaced by Portland cement in the 1850s.[7] In 1811, James Frost produced a cement he called British cement.[8] James Frost is reported to have erected a manufactory for making of an artificial cement in 1826.[9] In 1811 Edgar Dobbs of Southwark patented a cement of the kind invented 7 years later by the French engineer Louis Vicat. Vicat's cement is an artificial hydraulic lime, and is considered the 'principal forerunner'[7] of Portland cement.

The name Portland cement is recorded in a directory published in 1823 being associated with a William Lockwood and possibly others.[10] In his 1824 cement patent, Joseph Aspdin called his invention "Portland cement" because of the its resemblance to Portland stone.[6] However, Aspdin's cement was nothing like modern Portland cement, but was a first step in the development of modern Portland cement, and has been called a 'proto-Portland cement'.[7]

William Aspdin had left his father's company, to form his own cement manufactury. In the 1840's William Aspdin, apparently accidentally, produced calcium silicates which are a middle step in the development of Portland cement. In 1848, William Aspdin further improved his cement. Then, in 1853, he moved to Germany, where he was involved in cement making.[10] William Aspdin made what could be called 'meso-Portland cement' (a mix of Portland cement and hydraulic lime).[11] Isaac Charles Johnson further refined the production of 'meso-Portland cement' (middle stage of development), and claimed to be the real father of Portland cement.[12]

In 1859, John Grant of the Metropolitan Board of Works, set out requirements for cement to be used in the London sewer project. This became a specification for Portland cement. The next development in the manufacture of Portland cement was the introduction of the rotary kiln, patented by Frederick Ransome in 1885 (U.K.) and 1886 (U.S.); which allowed a stronger, more homogeneous mixture and a continuous manufacturing process.[7] The Hoffmann 'endless' kiln which was said to give 'perfect control over combustion' was tested in 1860, and showed the process produced a better grade of cement. This cement was made at the Portland Cementfabrik Stern at Stettin, which was the first to use a Hoffmann kiln.[13]. The Association of German Cement Manufacturers issued a standard on Portland cement in 1878.[14]

Portland cement had been imported into the United States from Germany and England, and in the 1870s and 1880s, it was being produced by Eagle Portland cement near Kalamazoo, Michigan. In 1875, the first Portland cement was produced in the Coplay Cement Company Kilns under the direction of David O. Saylor in Coplay, Pennsylvania.[15] By the early 20th century, American-made Portland cement had displaced most of the imported Portland cement.

Composition

ASTM C150[2] defines Portland cement as 'hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product) produced by pulverizing clinkers which consist essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an inter ground addition'.[16] The European Standard EN 197-1 uses the following definition:

Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates, (3 CaO·SiO2, and 2 CaO·SiO2), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium oxide content (MgO) shall not exceed 5.0% by mass.

(The last two requirements were already set out in the German Standard, issued in 1909).

Clinkers make up more than 90% of the cement, along with a limited amount of calcium sulfate (CaSO4, which controls the set time), and up to 5% minor constituents (fillers) as allowed by various standards. Clinkers are nodules (diameters, 0.2–1.0 inch [5.1–25.4 millimetres]) of a sintered material that is produced when a raw mixture of predetermined composition is heated to high temperature. The key chemical reaction which defines Portland cement from other hydraulic limes occurs at these high temperatures (>1,300 °C (2,370 °F)) as belite (Ca2SiO4) combines with calcium oxide (CaO) to form alite (Ca3SiO5).[17]

Manufacturing

Portland cement clinker is made by heating, in a cement kiln, a mixture of raw materials to a calcining temperature of above 600 °C (1,112 °F) and then a fusion temperature, which is about 1,450 °C (2,640 °F) for modern cements, to sinter the materials into clinker. The materials in cement clinker are alite, belite, tri-calcium aluminate, and tetra-calcium alumino ferrite. The aluminium, iron, and magnesium oxides are present as a flux allowing the calcium silicates to form at a lower temperature,[18] and contribute little to the strength. For special cements, such as low heat (LH) and sulfate resistant (SR) types, it is necessary to limit the amount of tricalcium aluminate (3 CaO·Al2O3) formed. The major raw material for the clinker-making is usually limestone (CaCO3) mixed with a second material containing clay as source of alumino-silicate. Normally, an impure limestone which contains clay or SiO2 is used. The CaCO3 content of these limestones can be as low as 80%. Secondary raw materials (materials in the raw mix other than limestone) depend on the purity of the limestone. Some of the materials used are clay, shale, sand, iron ore, bauxite, fly ash, and slag. When a cement kiln is fired by coal, the ash of the coal acts as a secondary raw material.

Cement grinding

LDCementFM10MW
A 10 MW cement mill, producing cement at 270 tonnes per hour.

To achieve the desired setting qualities in the finished product, a quantity (2–8%, but typically 5%) of calcium sulfate (usually gypsum or anhydrite) is added to the clinker, and the mixture is finely ground to form the finished cement powder. This is achieved in a cement mill. The grinding process is controlled to obtain a powder with a broad particle size range, in which typically 15% by mass consists of particles below 5 μm diameter, and 5% of particles above 45 μm. The measure of fineness usually used is the 'specific surface area', which is the total particle surface area of a unit mass of cement. The rate of initial reaction (up to 24 hours) of the cement on addition of water is directly proportional to the specific surface area. Typical values are 320–380 m2·kg−1 for general purpose cements, and 450–650 m2·kg−1 for 'rapid hardening' cements. The cement is conveyed by belt or powder pump to a silo for storage. Cement plants normally have sufficient silo space for one to 20 weeks of production, depending upon local demand cycles. The cement is delivered to end users either in bags, or as bulk powder blown from a pressure vehicle into the customer's silo. In industrial countries, 80% or more of cement is delivered in bulk.

Typical constituents of Portland clinker plus gypsum
Cement chemist notation under CCN.
clinker CCN mass (%)
Tricalcium silicate (CaO)3 · SiO2 C3S 45–75%
Dicalcium silicate (CaO)2 · SiO2 C2S  7–32%
Tricalcium aluminate (CaO)3 · Al2O3 C3A  0–13%
Tetracalcium aluminoferrite (CaO)4 · Al2O3 · Fe2O3 C4AF  0–18%
Gypsum CaSO4 · 2 H2O CS̅H2  2–10%
Typical constituents of Portland cement
Cement chemist notation under CCN.
cement CCN mass (%)
Calcium oxide, CaO C 61–67%
Silicon dioxide, SiO2 S 19–23%
Aluminium oxide, Al2O3 A  2.5–6%
Ferric oxide, Fe2O3 F  0–6%
Sulfur (VI) oxide, SO3 1.5–4.5%

Setting and hardening

Cement sets when mixed with water by way of a complex series of chemical reactions still only partly understood. The different constituents slowly crystallise, and the interlocking of their crystals gives cement its strength. Carbon dioxide is slowly absorbed to convert the portlandite (Ca(OH)2) into insoluble calcium carbonate. After the initial setting, immersion in warm water will speed up setting. Gypsum is added as an inhibitor to prevent flash (or quick) setting.

Use

Grosvenor estate, Westminster, London
Decorative use of Portland cement panels on London's Grosvenor estate[19]

The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Concrete can be used in the construction of structural elements like panels, beams, and street furniture, or may be cast-in situ for superstructures like roads and dams. These may be supplied with concrete mixed on site, or may be provided with 'ready-mixed' concrete made at permanent mixing sites. Portland cement is also used in mortars (with sand and water only), for plasters and screeds, and in grouts (cement/water mixes squeezed into gaps to consolidate foundations, road-beds, etc.).

When water is mixed with Portland cement, the product sets in a few hours, and hardens over a period of weeks. These processes can vary widely, depending upon the mix used and the conditions of curing of the product, but a typical concrete sets in about 6 hours and develops a compressive strength of 8 MPa in 24 hours. The strength rises to 15 MPa at 3 days, 23 MPa at 1 week, 35 MPa at 4 weeks, and 41 MPa at 3 months. In principle, the strength continues to rise slowly as long as water is available for continued hydration, but concrete is usually allowed to dry out after a few weeks and this causes strength growth to stop.

Types

ASTM C150

Five types of Portland cements exist, with variations of the first three according to ASTM C150.[2][20]

Type I Portland cement is known as common or general-purpose cement. It is generally assumed unless another type is specified. It is commonly used for general construction, especially when making precast, and precast-prestressed concrete that is not to be in contact with soils or ground water. The typical compound compositions of this type are:

55% (C3S), 19% (C2S), 10% (C3A), 7% (C4AF), 2.8% MgO, 2.9% (SO3), 1.0% ignition loss, and 1.0% free CaO (utilizing Cement chemist notation).

A limitation on the composition is that the (C3A) shall not exceed 15%.

Type II provides moderate sulfate resistance, and gives off less heat during hydration. This type of cement costs about the same as type I. Its typical compound composition is:

51% (C3S), 24% (C2S), 6% (C3A), 11% (C4AF), 2.9% MgO, 2.5% (SO3), 0.8% ignition loss, and 1.0% free CaO.

A limitation on the composition is that the (C3A) shall not exceed 8%, which reduces its vulnerability to sulfates. This type is for general construction exposed to moderate sulfate attack, and is meant for use when concrete is in contact with soils and ground water, especially in the western United States due to the high sulfur content of the soils. Because of similar price to that of type I, type II is much used as a general purpose cement, and the majority of Portland cement sold in North America meets this specification.

Note: Cement meeting (among others) the specifications for types I and II has become commonly available on the world market.

Type III has relatively high early strength. Its typical compound composition is: 57% (C3S), 19% (C2S), 10% (C3A), 7% (C4AF), 3.0% MgO, 3.1% (SO3), 0.9% ignition loss, and 1.3% free CaO. This cement is similar to type I, but ground finer. Some manufacturers make a separate clinker with higher C3S and/or C3A content, but this is increasingly rare, and the general purpose clinker is usually used, ground to a specific surface area typically 50–80% higher. The gypsum level may also be increased a small amount. This gives the concrete using this type of cement a three-day compressive strength equal to the seven-day compressive strength of types I and II. Its seven-day compressive strength is almost equal to 28-day compressive strengths of types I and II. The only downside is that the six-month strength of type III is the same or slightly less than that of types I and II. Therefore, the long-term strength is sacrificed. It is usually used for precast concrete manufacture, where high one-day strength allows fast turnover of molds. It may also be used in emergency construction and repairs, and construction of machine bases and gate installations.

Type IV Portland cement is generally known for its low heat of hydration. Its typical compound composition is: 28% (C3S), 49% (C2S), 4% (C3A), 12% (C4AF), 1.8% MgO, 1.9% (SO3), 0.9% ignition loss, and 0.8% free CaO. The percentages of (C2S) and (C4AF) are relatively high and (C3S) and (C3A) are relatively low. A limitation on this type is that the maximum percentage of (C3A) is seven, and the maximum percentage of (C3S) is thirty-five. This causes the heat given off by the hydration reaction to develop at a slower rate. However, as a consequence the strength of the concrete develops slowly. After one or two years the strength is higher than the other types after full curing. This cement is used for very large concrete structures, such as dams, which have a low surface to volume ratio. This type of cement is generally not stocked by manufacturers, but some might consider a large special order. This type of cement has not been made for many years, because Portland-pozzolan cements and ground granulated blast furnace slag addition offer a cheaper and more reliable alternative.

Type V is used where sulfate resistance is important. Its typical compound composition is: 38% (C3S), 43% (C2S), 4% (C3A), 9% (C4AF), 1.9% MgO, 1.8% (SO3), 0.9% ignition loss, and 0.8% free CaO. This cement has a very low (C3A) composition which accounts for its high sulfate resistance. The maximum content of (C3A) allowed is 5% for type V Portland cement. Another limitation is that the (C4AF) + 2(C3A) composition cannot exceed 20%. This type is used in concrete to be exposed to alkali soil and ground water sulfates which react with (C3A) causing disruptive expansion. It is unavailable in many places, although its use is common in the western United States and Canada. As with type IV, type V Portland cement has mainly been supplanted by the use of ordinary cement with added ground granulated blast furnace slag or tertiary blended cements containing slag and fly ash.

Types Ia, IIa, and IIIa have the same composition as types I, II, and III. The only difference is that in Ia, IIa, and IIIa, an air-entraining agent is ground into the mix. The air-entrainment must meet the minimum and maximum optional specification found in the ASTM manual. These types are only available in the eastern United States and Canada, only on a limited basis. They are a poor approach to air-entrainment which improves resistance to freezing under low temperatures.

Types II(MH) and II(MH)a have a similar composition as types II and IIa, but with a mild heat.

EN 197 norm

The European norm EN 197-1 defines five classes of common cement that comprise Portland cement as a main constituent. These classes differ from the ASTM classes.

CEM I Portland cement Comprising Portland cement and up to 5% of minor additional constituents
CEM II Portland-composite cement Portland cement and up to 35% of other single constituents
CEM III Blastfurnace cement Portland cement and higher percentages of blastfurnace slag
CEM IV Pozzolanic cement Portland cement and up to 55% of pozzolanic constituents
CEM V Composite cement Portland cement, blastfurnace slag or fly ash and pozzolana

Constituents that are permitted in Portland-composite cements are artificial pozzolans (blastfurnace slag (in fact a latent hydraulic binder), silica fume, and fly ashes), or natural pozzolans (siliceous or siliceous aluminous materials such as volcanic ash glasses, calcined clays and shale).

CSA A3000-08

The Canadian standards describe six main classes of cement, four of which can also be supplied as a blend containing ground limestone (where a suffix L is present in the class names).

GU, GUL (a.k.a. Type 10 (GU) cement) > General use cement

MS > Moderate sulphate resistant cement

MH, MHL > Moderate heat cement

HE, HEL > High early strength cement

LH, LHL > Low heat cement

HS > High sulphate resistant; generally develops strength less rapidly than the other types.

White Portland cement

White Portland cement or white ordinary Portland cement (WOPC) is similar to ordinary, grey, Portland cement in all respects, except for its high degree of whiteness. Obtaining this colour requires high purity raw materials (low Fe2O3 content), and some modification to the method of manufacture, among others a higher kiln temperature required to sinter the clinker in the absence of ferric oxides acting as a flux in normal clinker. As Fe2O3 contributes to decrease the melting point of the clinker (normally 1450 °C), the white cement requires a higher sintering temperature (around 1600 °C). Because of this, it is somewhat more expensive than the grey product. The main requirement is to have a low iron content which should be less than 0.5 wt.% expressed as Fe2O3 for white cement, and less than 0.9 wt.% for off-white cement. It also helps to have the iron oxide as ferrous oxide (FeO) which is obtained via slightly reducing conditions in the kiln, i.e., operating with zero excess oxygen at the kiln exit. This gives the clinker and cement a green tinge. Other metallic oxides such as Cr2O3 (green), MnO (pink), TiO2 (white), etc., in trace content, can also give colour tinges, so for a given project it is best to use cement from a single batch.

Safety issues

Bags of cement routinely have health and safety warnings printed on them, because not only is cement highly alkaline, but the setting process is also exothermic. As a result, wet cement is strongly caustic, and can easily cause severe skin burns if not promptly washed off with water. Similarly, dry cement powder in contact with mucous membranes can cause severe eye or respiratory irritation.[21][22][23][24] The reaction of cement dust with moisture in the sinuses and lungs can also cause a chemical burn, as well as headaches, fatigue,[25] and lung cancer.[26]

The production of comparatively low-alkalinity cements (pH<11) is an area of ongoing investigation.[27]

In Scandinavia, France, and the United Kingdom, the level of chromium(VI), which is considered to be toxic and a major skin irritant, may not exceed 2 parts per million (ppm).

In the US, the Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for Portland cement exposure in the workplace as 50 mppcf (million particles per cubic foot) over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 10 mg/m3 total exposure and 5 mg/m3 respiratory exposure over an 8-hour workday. At levels of 5000 mg/m3, Portland cement is immediately dangerous to life and health.[28]

Environmental effects

Portland cement manufacture can cause environmental impacts at all stages of the process. These include emissions of airborne pollution in the form of dust; gases; noise and vibration when operating machinery and during blasting in quarries; consumption of large quantities of fuel during manufacture; release of CO2 from the raw materials during manufacture, and damage to countryside from quarrying. Equipment to reduce dust emissions during quarrying and manufacture of cement is widely used, and equipment to trap and separate exhaust gases are coming into increased use. Environmental protection also includes the re-integration of quarries into the countryside after they have been closed down by returning them to nature or re-cultivating them.

Epidemiologic Notes and Reports Sulfur Dioxide Exposure in Portland Cement Plants, from the Centers for Disease Control, states "Workers at Portland cement facilities, particularly those burning fuel containing sulfur, should be aware of the acute and chronic effects of exposure to SO2 [sulfur dioxide], and peak and full-shift concentrations of SO2 should be periodically measured."

— [29]

An independent research effort of AEA Technology to identify critical issues for the cement industry today concluded the most important environment, health and safety performance issues facing the cement industry are atmospheric releases (including greenhouse gas emissions, dioxin, NOx, SO2, and particulates), accidents, and worker exposure to dust.[30]

The CO2 associated with Portland cement manufacture comes from three sources:

  1. CO2 derived from decarbonation of limestone,
  2. CO2 from kiln fuel combustion,
  3. CO2 produced by vehicles in cement plants and distribution.

Source 1 is fairly constant: minimum around 0.47 kg CO2 per kg of cement, maximum 0.54, typical value around 0.50 worldwide. Source 2 varies with plant efficiency: efficient precalciner plant 0.24 kg CO2 per kg cement, low-efficiency wet process as high as 0.65, typical modern practices (e.g. UK) averaging around 0.30. Source 3 is almost insignificant at 0.002–0.005. So typical total CO2 is around 0.80 kg CO2 per kg finished cement. This omits the CO2 associated with electric power consumption, because this varies according to the local generation type and efficiency. Typical electrical energy consumption is of the order of 90–150 kWh per tonne cement, equivalent to 0.09–0.15 kg CO2 per kg finished cement if the electricity is coal-generated.

Overall, with nuclear- or hydroelectric power, and efficient manufacturing, CO2 generation can be reduced to 0.7 kg per kg cement, but can be twice as high. The thrust of innovation for the future is to reduce sources 1 and 2 by modification of the chemistry of cement, by the use of wastes, and by adopting more efficient processes. Although cement manufacturing is clearly a very large CO2 emitter, concrete (of which cement makes up about 15%) compares quite favourably with other building systems in this regard.

Cement plants used for waste disposal or processing

LDWisconsinTireInject
Used tyres being fed to a pair of cement kilns

Due to the high temperatures inside cement kilns, combined with the oxidising (oxygen-rich) atmosphere and long residence times, cement kilns are used as a processing option for various types of waste streams; indeed, they efficiently destroy many hazardous organic compounds. The waste streams also often contain combustible materials which allow the substitution of part of the fossil fuel normally used in the process.

Waste materials used in cement kilns as a fuel supplement:[31]

Portland cement manufacture also has the potential to benefit from using industrial byproducts from the waste stream.[32] These include in particular:

See also

References

  1. ^ a b Courland, Robert (2011). Concrete planet : the strange and fascinating story of the world's most common man-made material. Amherst, N.Y.: Prometheus Books. ISBN 978-1616144814. Retrieved 28 August 2015.
  2. ^ a b c "ASTM C185-15a, Standard Test Method for Air Content of Hydraulic Cement Mortar". www.ASTM.org. West Conshohocken, PA: ASTM International. 2015. doi:10.1520/C0185-15A. Retrieved 16 May 2017.
  3. ^ Scrivener, Karen L.; John, Vanderley M.; Gartner, Ellis M. (June 2018). "Eco-efficient cements: Potential economically viable solutions for a low-CO 2 cement-based materials industry" (PDF). Cement and Concrete Research. 114: 2–26. doi:10.1016/j.cemconres.2018.03.015.
  4. ^ "Technology Roadmap - Low-Carbon Transition in the Cement Industry: Foldout". IEA webstore.
  5. ^ Lothenbach, Barbara; Scrivener, Karen; Hooton, R.D. (December 2011). "Supplementary cementitious materials". Cement and Concrete Research. 41 (12): 1244–1256. doi:10.1016/j.cemconres.2010.12.001.
  6. ^ a b Gillberg, B. Fagerlund, G. Jönsson, Å. Tillman, A-M. (1999). Betong och miljö [Concrete and environment] (in Swedish). Stockholm: AB Svensk Byggtjenst. ISBN 978-91-7332-906-4.CS1 maint: multiple names: authors list (link)
  7. ^ a b c d e Robert G. Blezard, "The History of Calcareous Cements" in Hewlett, Peter C., ed.. Leaʼs chemistry of cement and concrete. 4. ed. Amsterdam: Elsevier Butterworth-Heinemann, 2004. 1–24. Print.
  8. ^ a b Saikia, Mimi Das. Bhargab Mohan Das, Madan Mohan Das. Elements of Civil Engineering. New Delhie: PHI Learning Private Limited. 2010. 30. Print.
  9. ^ Reid, Henry (1868). A practical treatise on the manufacture of Portland Cement. London: E. & F.N. Spon.
  10. ^ a b Francis, A.J. (1977). The Cement Industry 1796–1914: A History.
  11. ^ 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.
  12. ^ Hahn, Thomas F., and Emory Leland Kemp. Cement mills along the Potomac River. Morgantown, WV: West Virginia University Press, 1994. 16. Print.
  13. ^ Reid, Henry (1877). The Science and Art of the Manufacture of Portland Cement with observations on some of its constructive applications. London: E&F.N. Spon.
  14. ^ "125 Years of Research for Quality and Progress". German Cement Works' Association. Archived from the original on 16 January 2015. Retrieved 30 September 2012.CS1 maint: BOT: original-url status unknown (link)
  15. ^ Meade, Richard Kidder. Portland cement: its composition, raw materials, manufacture, testing and analysis. Easton, PA: 1906. The Chemical Publishing Co. 4–14. Print.
  16. ^ "Portland Cement". dot.gov. Archived from the original on 7 June 2014.
  17. ^ Dylan Moore. "Cement Kilns: Clinker Thermochemistry". cementkilns.co.uk. Archived from the original on 6 March 2014.
  18. ^ McArthur, Hugh, and Duncan Spalding. Engineering materials science: properties, uses, degradation and remediation. Chichester, U.K.: Horwood Pub., 2004. 217. Print.
  19. ^ "Housing Prototypes: Page Street". housingprototypes.org. Archived from the original on 16 September 2012.
  20. ^ The contractor's guide to quality concrete construction. 3rd ed. St. Louis, MO: American Society of Concrete Contractors ;, 2005. 17. Print.
  21. ^ "Archived copy" (PDF). Archived (PDF) from the original on 4 June 2011. Retrieved 15 February 2011.CS1 maint: archived copy as title (link)
  22. ^ "Mother left with horrific burns to her knees after kneeling in B&Q cement while doing kitchen DIY". Daily Mail. London. 15 February 2011.
  23. ^ Pyatt, Jamie (15 February 2011). "Mums horror cement burns". The Sun. London. Archived from the original on 7 November 2011.
  24. ^ Bolognia, Jean L.; Joseph L. Jorizzo; Ronald P. Rapini (2003). Dermatology, volume 1. Mosby. ISBN 978-0-323-02409-9.
  25. ^ Oleru, U. G. (1984). "Pulmonary function and symptoms of Nigerian workers exposed to cement dust". Environ. Research. 33 (2): 379–385. Bibcode:1984ER.....33..379O. doi:10.1016/0013-9351(84)90036-7.
  26. ^ Rafnsson, V; H. Gunnarsdottir; M. Kiilunen (1997). "Risk of lung cancer among masons in Iceland". Occup. Environ. Med. 54 (3): 184–188. doi:10.1136/oem.54.3.184. PMC 1128681. PMID 9155779.
  27. ^ Coumes, Céline Cau Dit; Simone Courtois; Didier Nectoux; Stéphanie Leclercq; Xavier Bourbon (December 2006). "Formulating a low-alkalinity, high-resistance and low-heat concrete for radioactive waste repositories". Cement and Concrete Research. Elsevier Ltd. 36 (12): 2152–2163. doi:10.1016/j.cemconres.2006.10.005.
  28. ^ "CDC – NIOSH Pocket Guide to Chemical Hazards – Portland cement". www.cdc.gov. Archived from the original on 21 November 2015. Retrieved 21 November 2015.
  29. ^ "Epidemiologic Notes and Reports Sulfur Dioxide Exposure in Portland Cement Plants". cdc.gov. Archived from the original on 25 June 2017.
  30. ^ "Toward a Sustainable Cement Industry: Environment, Health & Safety Performance Improvement" (PDF). wbcsd.ch. Archived (PDF) from the original on 28 September 2007.
  31. ^ Chris Boyd (December 2001). "Recovery of Wastes in Cement Kilns" (PDF). World Business Council for Sustainable Development. Archived from the original (PDF) on 24 June 2008. Retrieved 25 September 2008.
  32. ^ S.H. Kosmatka; W.C. Panarese (1988). Design and Control of Concrete Mixtures. Skokie, Illinois: Portland Cement Association. p. 15. ISBN 978-0-89312-087-0. As a generalization, probably 50% of all industrial byproducts have potential as raw materials for the manufacture of Portland cement.

External links

Aalborg Portland

Aalborg Portland is a cement-producing company in Denmark. It was established in Aalborg in the 19th century. Portland cement was patented in 1824 by the Englishman Joseph Aspdin. Six decades later the Aalborg businessman Hans Holm and the engineer Frederick Læssøe Smidth built a cement factory 4 kilometres (2.5 mi) northeast of Aalborg in the town of Rørdal.

The Aalborg Portland-Cement Factory was founded in 1889. Aalborg Portland produces four major products: grey cement, white cement, ready-mixed concrete and aggregates. In 2009 the Sinai White Portland Cement division became the "biggest white cement integrated plant worldwide in terms of capacity". Since 2003, the company is a subsidiary of Cementir Holding S.p.A. The sale was approved by competition authorities in 2004. In 2013 it had a workforce of over 1,500.

Blue Circle Industries

Blue Circle Industries was a British public company manufacturing cement. It was founded in 1900 as the Associated Portland Cement Manufacturers Ltd through the fusion of 24 cement works, mostly located on the Thames and Medway estuaries, together having around a 70% market share of the British cement market. In 1911, the British Portland Cement Manufacturers Ltd. was formed by the addition of a further 35 companies, creating a company with an initial 80% of the British cement market.

Subsequently, the company expanded overseas, predominantly into commonwealth countries and South and Central America. The energy crisis of the 1970 caused the contraction of the company, and the sale of its overseas plants. In 1978, the company officially changed its name to Blue Circle.

In 2001 the company was bought by Lafarge.

Cement

A cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cement is the most widely used material in existence and is only behind water as the planet's most-consumed resource.Cements used in construction are usually inorganic, often lime or calcium silicate based, and can be characterized as either hydraulic or non-hydraulic, depending on the ability of the cement to set in the presence of water (see hydraulic and non-hydraulic lime plaster).

Non-hydraulic cement does not set in wet conditions or under water. Rather, it sets as it dries and reacts with carbon dioxide in the air. It is resistant to attack by chemicals after setting.

Hydraulic cements (e.g., Portland cement) set and become adhesive due to a chemical reaction between the dry ingredients and water. The chemical reaction results in mineral hydrates that are not very water-soluble and so are quite durable in water and safe from chemical attack. This allows setting in wet conditions or under water and further protects the hardened material from chemical attack. The chemical process for hydraulic cement found by ancient Romans used volcanic ash (pozzolana) with added lime (calcium oxide).

The word "cement" can be traced back to the Roman term opus caementicium, used to describe masonry resembling modern concrete that was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick supplements that were added to the burnt lime, to obtain a hydraulic binder, were later referred to as cementum, cimentum, cäment, and cement. In modern times, organic polymers are sometimes used as cements in concrete.

Clinker (cement)

In the manufacture of Portland cement, clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter, produced by sintering (fusing together without melting to the point of liquefaction) limestone and aluminosilicate materials such as clay during the cement kiln stage.

Concrete

Concrete, usually Portland cement concrete (for its visual resemblance to Portland stone), is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens over time—most frequently in the past a lime-based cement binder, such as lime putty, but sometimes with other hydraulic cements, such as a calcium aluminate cement or Portland cement. It is distinguished from other, non-cementitious types of concrete all binding some form of aggregate together, including asphalt concrete with a bitumen binder, which is frequently used for road surfaces, and polymer concretes that use polymers as a binder.

When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape. The cement reacts with the water and other ingredients to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. Often, additives (such as pozzolans or superplasticizers) are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials (such as rebar) embedded to provide tensile strength, yielding reinforced concrete.

Concrete is one of the most frequently used building materials. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminum combined. Globally, the ready-mix concrete industry, the largest segment of the concrete market, is projected to exceed $600 billion in revenue by 2025.

Edison Portland Cement Company

The Edison Portland Cement Company was a venture by Thomas Edison that helped to improve the Portland cement industry. Edison was developing an iron ore milling process and discovered a market in the sale of waste sand to cement manufacturers. He decided to set up his own cement company, founding it in New Village, New Jersey in 1899, and went on to supply the concrete for the construction of Yankee Stadium in 1922.

Energetically modified cement

Energetically modified cements (EMC) are a class of cementitious materials made from pozzolans (e.g. fly ash, volcanic ash, pozzolana), silica sand, blast furnace slag, or Portland cement (or blends of these ingredients).

Fly ash

Fly ash or flue ash, also known as pulverised fuel ash in the United Kingdom, is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired boilers together with the flue gases. Ash that falls to the bottom of the boiler's combustion chamber (commonly called a firebox) is called bottom ash. In modern coal-fired power plants, fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys. Together with bottom ash removed from the bottom of the boiler, it is known as coal ash. Depending upon the source and composition of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline), aluminium oxide (Al2O3) and calcium oxide (CaO), the main mineral compounds in coal-bearing rock strata.

The minor constituents of fly ash depend upon the specific coal bed composition but may include one or more of the following elements or compounds found in trace concentrations (up to hundreds ppm): arsenic, beryllium, boron, cadmium, chromium, hexavalent chromium, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium, along with very small concentrations of dioxins and PAH compounds. It also has unburnt carbon.In the past, fly ash was generally released into the atmosphere, but air pollution control standards now require that it be captured prior to release by fitting pollution control equipment. In the United States, fly ash is generally stored at coal power plants or placed in landfills. About 43% is recycled, often used as a pozzolan to produce hydraulic cement or hydraulic plaster and a replacement or partial replacement for Portland cement in concrete production. Pozzolans ensure the setting of concrete and plaster and provide concrete with more protection from wet conditions and chemical attack.

In the case that fly (or bottom) ash is not produced from coal, for example when solid waste is incinerated in a waste-to-energy facility to produce electricity, the ash may contain higher levels of contaminants than coal ash. In that case the ash produced is often classified as hazardous waste.

Ground granulated blast-furnace slag

Ground-granulated blast-furnace slag (GGBS or GGBFS) is obtained by quenching molten iron slag (a by-product of iron and steel-making) from a blast furnace in water or steam, to produce a glassy, granular product that is then dried and ground into a fine powder.

Lafarge (company)

Lafarge S.A. is a French industrial company specialising in three major products: cement, construction aggregates, and concrete.

On 10 July 2015 Lafarge merged with Holcim, a Swiss cement company. On 15 July the new company was officially launched around the globe under the name of LafargeHolcim, creating a new leader in the Building Materials sector.

Lime mortar

Lime mortar is composed of lime and an aggregate such as sand, mixed with water. The Ancient Egyptians were the first to use lime mortars. About 6,000 years ago, they used lime to plaster the pyramids at Giza. In addition, the Egyptians also incorporated various limes into their religious temples as well as their homes. Indian traditional structures built with lime mortar, which are more than 4,000 years old like Mohenjo-daro is still a heritage monument of Indus valley civilization in Pakistan. It is one of the oldest known types of mortar also used in ancient Rome and Greece, when it largely replaced the clay and gypsum mortars common to ancient Egyptian construction.With the introduction of Portland cement during the 19th century, the use of lime mortar in new constructions gradually declined. This was largely due to the ease of use of Portland cement, its quick setting, and high compressive strength. However, the soft and porous properties of lime mortar provide certain advantages when working with softer building materials such as natural stone and terracotta. For this reason, while Portland cement continues to be commonly used in new constructions of brick and concrete construction, in the repair and restoration of brick and stone-built structures originally built using lime mortar, the use of Portland cement is not recommended.Despite its enduring utility over many centuries, lime mortar's effectiveness as a building material has not been well understood; time-honoured practices were based on tradition, folklore and trade knowledge, vindicated by the vast number of old buildings that remain standing. Only during the last few decades has empirical testing provided a scientific understanding of its remarkable durability.

Mortar (masonry)

Mortar is a workable paste used to bind building blocks such as stones, bricks, and concrete masonry units, fill and seal the irregular gaps between them, and sometimes add decorative colors or patterns in masonry walls. In its broadest sense mortar includes pitch, asphalt, and soft mud or clay, such as used between mud bricks. Mortar comes from Latin mortarium meaning crushed.

Cement mortar becomes hard when it cures, resulting in a rigid aggregate structure; however, the mortar is intended to be weaker than the building blocks and the sacrificial element in the masonry, because the mortar is easier and less expensive to repair than the building blocks. Mortars are typically made from a mixture of sand, a binder, and water. The most common binder since the early 20th century is Portland cement but the ancient binder lime mortar is still used in some new construction. Lime and gypsum in the form of plaster of Paris are used particularly in the repair and repointing of buildings and structures because it is important the repair materials are similar to the original materials. The type and ratio of the repair mortar is determined by a mortar analysis. There are several types of cement mortars and additives.

Oregon Portland Cement Building

The Oregon Portland Cement Building is a building in southeast Portland, Oregon listed on the National Register of Historic Places.

Portland Cement Association

Portland Cement Association is a non-profit organization that promotes the use of concrete. The organization conducts and sponsors concrete research projects, participates in the setting of industry standards of cement manufacturing, disseminates free designs of concrete-based architectural structures and its elements, etc.

Ramco Cements

The Ramco Cements Limited (formerly Madras Cements Ltd) is the flagship company of the Ramco Group, a business group based in Chennai, India. P R Venketrama Raja is the owner of the company. It is the fifth largest cement producer in India. The company also produces ready mix concrete and dry mortar products and operates wind farms.

The main product of the company is Portland cement, manufactured in eight state-of-the art production facilities that includes Integrated Cement plants and Grinding units with a current total production capacity of 16.45 MTPA (out of which Satellite Grinding units capacity alone is 4 MTPA).Ramco Supergrade is the most popular cement brand in South India.

It manufactures and markets Portland cement, blast furnace slag cement, white cement and Pozzolana cement. The company has production facilities at Alathiyur, Chengalpet, Kolaghat, Medavakkam, Sriperumpudur, Jaggaiahpet, Virudhunagar and Vizag in India.

Ramco opened its first windfarm at Muppandal in 1993. In 1995, Ramco Cements installed 69 additional windmills at Poolavadi near Coimbatore. As of 2019, the total installed windmill capacity is with 165.785 MW with 235 individual units.

Rillito, Arizona

Rillito is a census-designated place (CDP) as well as a populated place in Pima County, Arizona, United States, completely surrounded by the town of Marana. The largest business in the community is Arizona Portland Cement and the community has had a post office since the 1920s. There is a regional park and recreation center (Rillito Vista Community Center) in the middle of the community. Rillito has the ZIP Code of 85654; in 2000, the population of the 85654 ZCTA was 148.

Roller-compacted concrete

Roller-compacted concrete (RCC) or rolled concrete (rollcrete) is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement. The partial substitution of fly ash for Portland Cement is an important aspect of RCC dam construction because the heat generated by fly ash hydration is significantly less than the heat generated by Portland Cement hydration. This in turn reduces the thermal loads on the dam and reduces the potential for thermal cracking to occur. RCC is a mix of cement/fly ash, water, sand, aggregate and common additives, but contains much less water. The produced mix is drier and essentially has no slump. RCC is placed in a manner similar to paving; the material is delivered by dump trucks or conveyors, spread by small bulldozers or specially modified asphalt pavers, and then compacted by vibratory rollers.

In dam construction, roller-compacted concrete began its initial development with the construction of the Alpe Gera Dam near Sondrio in North Italy between 1961 and 1964. Concrete was laid in a similar form and method but not rolled. RCC had been touted in engineering journals during the 1970s as a revolutionary material suitable for, among other things, dam construction. Initially and generally, RCC was used for backfill, sub-base and concrete pavement construction, but increasingly it has been used to build concrete gravity dams because the low cement content and use of fly ash cause less heat to be generated while curing than do conventional mass concrete placements. Roller-compacted concrete has many time and cost benefits over conventional mass concrete dams; these include higher rates of concrete placement, lower material costs and lower costs associated with post-cooling and formwork.

Stucco

Stucco or render is a construction material made of aggregates, a binder, and water. Stucco is applied wet and hardens to a very dense solid. It is used as a decorative coating for walls and ceilings, and as a sculptural and artistic material in architecture. Stucco may be used to cover less visually appealing construction materials, such as metal, concrete, cinder block, or clay brick and adobe.

In English, "stucco" usually refers to a coating for the outside of a building and "plaster" to a coating for interiors; as described below, the material itself is often little different. However, other European languages, notably including Italian, do not have the same distinction; stucco means plaster in Italian and serves for both. This has led to English-speakers sometimes using "stucco" for interior decorative plasterwork in relief.

Yocemento, Kansas

Yocemento is an unincorporated community in Big Creek Township, Ellis County, Kansas, United States. The settlement lies across the banks of Big Creek where the seasonal stream meanders against the base of bluffs capped by massive limestone blocks, in which lies the 20th-century origin of the community.The original settler name for the location was Hog Back, with a railway station first established there with that name in 1881. Hog Back was the local name for the high limestone and chalk ridge that runs from just west of old Fort Hays to Ellis (this station was later moved -- see Hog Back, Kansas). These bluffs are the local outcrop of the Fort Hays Limestone. Founded in 1906 by business partners Erasmus Haworth, the first state geologist of Kansas, and I. M. Yost, leading businessman and miller of Hays, Yocemento is one of the several communities around the outskirts of the High Plains that were founded to use Fort Hays Limestone to manufacture Portland cement.

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