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63-430: The roof and walls are constructed of exposed, reinforced in-situ cast concrete . The geometric design and forced perspectives give the sense of movement and momentum. Its construction began in 1991 and ended in 1993. The exterior of the building consists of sharply angled planar surfaces. The architecture of the building has been likened to Deconstructivism . The building was constructed as a self-contained fire station for

126-411: A calcium aluminate cement or with Portland cement to form Portland cement concrete (named for its visual resemblance to Portland stone ). Many other non-cementitious types of concrete exist with other methods of binding 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. Concrete

189-433: A French structural and civil engineer . Concrete components or structures are compressed by tendon cables during, or after, their fabrication in order to strengthen them against tensile forces developing when put in service. Freyssinet patented the technique on 2 October 1928. Concrete is an artificial composite material , comprising a matrix of cementitious binder (typically Portland cement paste or asphalt ) and

252-452: A cementitious material forms a cement paste by the process of hydration. The cement paste glues the aggregate together, fills voids within it, and makes it flow more freely. As stated by Abrams' law , a lower water-to-cement ratio yields a stronger, more durable concrete, whereas more water gives a freer-flowing concrete with a higher slump . The hydration of cement involves many concurrent reactions. The process involves polymerization ,

315-400: A concrete component—and become a part of the binder for the aggregate. Fly ash and slag can enhance some properties of concrete such as fresh properties and durability. Alternatively, other materials can also be used as a concrete binder: the most prevalent substitute is asphalt , which is used as the binder in asphalt concrete . Admixtures are added to modify the cure rate or properties of

378-434: A dispersed phase or "filler" of aggregate (typically a rocky material, loose stones, and sand). The binder "glues" the filler together to form a synthetic conglomerate . Many types of concrete are available, determined by the formulations of binders and the types of aggregate used to suit the application of the engineered material. These variables determine strength and density, as well as chemical and thermal resistance of

441-437: A fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water , and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. 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

504-452: A greater degree of fracture resistance even in seismically active environments. Roman concrete is significantly more resistant to erosion by seawater than modern concrete; it used pyroclastic materials which react with seawater to form Al- tobermorite crystals over time. The use of hot mixing and the presence of lime clasts are thought to give the concrete a self-healing ability, where cracks that form become filled with calcite that prevents

567-415: A large aggregate that is too large for the size of the formwork, or which has too few smaller aggregate grades to serve to fill the gaps between the larger grades, or using too little or too much sand for the same reason, or using too little water, or too much cement, or even using jagged crushed stone instead of smoother round aggregate such as pebbles. Any combination of these factors and others may result in

630-461: A large type of industrial facility called a concrete plant , or often a batch plant. The usual method of placement is casting in formwork , which holds the mix in shape until it has set enough to hold its shape unaided. Concrete plants come in two main types, ready-mix plants and central mix plants. A ready-mix plant blends all of the solid ingredients, while a central mix does the same but adds water. A central-mix plant offers more precise control of

693-615: A lightning strike caused a fire at the Vitra Furniture factory in Weil am Rhein , Germany. Business interruption insurance covered the loss from the factory shut down due to the damage from the fire. Architect Nicholas Grimshaw was given the project of rebuilding the factory. In an interview, Vitra director Rolf Fehlbaum described his decision to work with him as influenced by Grimshaw's approach of being similar to product design, comparing him to Charles and Ray Eames . After six months

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756-434: A mix which is too harsh, i.e., which does not flow or spread out smoothly, is difficult to get into the formwork, and which is difficult to surface finish. Exothermic process In thermodynamics , an exothermic process (from Ancient Greek έξω ( éxō )  'outward' and θερμικός ( thermikós )  'thermal') is a thermodynamic process or reaction that releases energy from

819-469: A mixture of calcium silicates ( alite , belite ), aluminates and ferrites —compounds, which will react with water. Portland cement and similar materials are made by heating limestone (a source of calcium) with clay or shale (a source of silicon, aluminium and iron) and grinding this product (called clinker ) with a source of sulfate (most commonly gypsum ). Cement kilns are extremely large, complex, and inherently dusty industrial installations. Of

882-405: A number of manufactured aggregates, including air-cooled blast furnace slag and bottom ash are also permitted. The size distribution of the aggregate determines how much binder is required. Aggregate with a very even size distribution has the biggest gaps whereas adding aggregate with smaller particles tends to fill these gaps. The binder must fill the gaps between the aggregate as well as paste

945-424: A semi-liquid slurry (paste) that can be shaped, typically by pouring it into a form. The concrete solidifies and hardens through a chemical process called hydration . The water reacts with the cement, which bonds the other components together, creating a robust, stone-like material. Other cementitious materials, such as fly ash and slag cement , are sometimes added—either pre-blended with the cement or directly as

1008-493: A simple, fast way of getting a basic idea of the properties of the finished concrete without having to perform testing in advance. Various governing bodies (such as British Standards ) define nominal mix ratios into a number of grades, usually ranging from lower compressive strength to higher compressive strength. The grades usually indicate the 28-day cure strength. Thorough mixing is essential to produce uniform, high-quality concrete. Separate paste mixing has shown that

1071-422: Is "a reaction for which the overall standard enthalpy change Δ H ⚬ is negative". Some examples of exothermic process are fuel combustion , condensation and nuclear fission , which is used in nuclear power plants to release large amounts of energy. In an endothermic reaction or system, energy is taken from the surroundings in the course of the reaction, usually driven by a favorable entropy increase in

1134-511: Is distinct from mortar . Whereas concrete is itself a building material, mortar is a bonding agent that typically holds bricks , tiles and other masonry units together. Grout is another material associated with concrete and cement. It does not contain coarse aggregates and is usually either pourable or thixotropic , and is used to fill gaps between masonry components or coarse aggregate which has already been put in place. Some methods of concrete manufacture and repair involve pumping grout into

1197-408: Is equal to the enthalpy change, i.e. while at constant volume , according to the first law of thermodynamics it equals internal energy ( U ) change, i.e. In an adiabatic system (i.e. a system that does not exchange heat with the surroundings), an otherwise exothermic process results in an increase in temperature of the system. In exothermic chemical reactions, the heat that is released by

1260-559: Is then blended with aggregates and any remaining batch water and final mixing is completed in conventional concrete mixing equipment. Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (pouring, pumping, spreading, tamping, vibration) and without reducing the concrete's quality. Workability depends on water content, aggregate (shape and size distribution), cementitious content and age (level of hydration ) and can be modified by adding chemical admixtures, like superplasticizer. Raising

1323-399: Is usually reinforced with materials that are strong in tension, typically steel rebar . The mix design depends on the type of structure being built, how the concrete is mixed and delivered, and how it is placed to form the structure. Portland cement is the most common type of cement in general usage. It is a basic ingredient of concrete, mortar , and many plasters . It consists of

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1386-480: The construction industry , whose demand is ever growing with greater impacts on raw material extraction, waste generation and landfill practices. Concrete production is the process of mixing together the various ingredients—water, aggregate, cement, and any additives—to produce concrete. Concrete production is time-sensitive. Once the ingredients are mixed, workers must put the concrete in place before it hardens. In modern usage, most concrete production takes place in

1449-643: The absence of reinforcement, its tensile strength was far lower than modern reinforced concrete , and its mode of application also differed: Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice, often consisted of rubble . Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon

1512-489: The building. It was the first building complex designed by Zaha Hadid. Starting with the fire station, she also designed the campus boundary walls, an exercise facility, and a bicycle shed. She noted: "There was no landscape, so we had to invent one. It was an un-place we had to make into a place." The fire station was risk management for a furniture factory that created furniture from designers Charles and Ray Eames, George Nelson , and Verner Panton . As mentioned above about

1575-630: The cisterns secret as these enabled the Nabataeans to thrive in the desert. Some of these structures survive to this day. In the Ancient Egyptian and later Roman eras, builders discovered that adding volcanic ash to lime allowed the mix to set underwater. They discovered the pozzolanic reaction . The Romans used concrete extensively from 300 BC to AD 476. During the Roman Empire, Roman concrete (or opus caementicium )

1638-414: The classical understanding of heat. In an exothermic reaction, the activation energy (energy needed to start the reaction) is less than the energy that is subsequently released, so there is a net release of energy. Some examples of exothermic processes are: Chemical exothermic reactions are generally more spontaneous than their counterparts, endothermic reactions . In a thermochemical reaction that

1701-401: The company was back in production. Fehlbaum was interested in architect Zaha Hadid designing furniture for Vitra. After the fire, the company created its own fire brigade and housed it in a makeshift structure. Hadid had a variety of drawings for projects that the company considered very dynamic. The company felt having its own fire brigade was also dynamic and assigned Hadid the project for

1764-526: The concrete at the time of batching/mixing. (See § Production below.) The common types of admixtures are as follows: Inorganic materials that have pozzolanic or latent hydraulic properties, these very fine-grained materials are added to the concrete mix to improve the properties of concrete (mineral admixtures), or as a replacement for Portland cement (blended cements). Products which incorporate limestone , fly ash , blast furnace slag , and other useful materials with pozzolanic properties into

1827-399: The concrete can cause the initially placed material to begin to set before the next batch is added on top. This creates a horizontal plane of weakness called a cold joint between the two batches. Once the mix is where it should be, the curing process must be controlled to ensure that the concrete attains the desired attributes. During concrete preparation, various technical details may affect

1890-461: The concrete quality. Central mix plants must be close to the work site where the concrete will be used, since hydration begins at the plant. A concrete plant consists of large hoppers for storage of various ingredients like cement, storage for bulk ingredients like aggregate and water, mechanisms for the addition of various additives and amendments, machinery to accurately weigh, move, and mix some or all of those ingredients, and facilities to dispense

1953-528: The crack from spreading. The widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon . After the Roman Empire, the use of burned lime and pozzolana

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2016-431: The finished product. Construction aggregates consist of large chunks of material in a concrete mix, generally a coarse gravel or crushed rocks such as limestone , or granite , along with finer materials such as sand . Cement paste, most commonly made of Portland cement , is the most prevalent kind of concrete binder. For cementitious binders, water is mixed with the dry cement powder and aggregate, which produces

2079-505: The firefighters allegedly found the building difficult to use for its purpose of a fire station. A few years later, the corporation disbanded its fire brigade and used the building for events and for exhibitions held by the Vitra Design Museum , which was designed by fellow deconstructivism proponent Frank Gehry . Concrete#Production Concrete is a composite material composed of aggregate bonded together with

2142-459: The form of heat. The concept is frequently applied in the physical sciences to chemical reactions where chemical bond energy is converted to thermal energy (heat). Exothermic and endothermic describe two types of chemical reactions or systems found in nature, as follows: An exothermic reaction occurs when heat is released to the surroundings. According to the IUPAC , an exothermic reaction

2205-455: The furniture factory after a fire destroyed parts of the factory in 1981. Architect Nicholas Grimshaw was hired to redesign of the damaged factory complex. His original proposal was a unified series of buildings. However, the company later chose to create a collection of buildings with varying styles. For the fire station, the company hired Zaha Hadid , whom it had been considering for the design of some of its furniture product line. In 1981,

2268-681: The gaps to make up a solid mass in situ . The word concrete comes from the Latin word " concretus " (meaning compact or condensed), the perfect passive participle of " concrescere ", from " con -" (together) and " crescere " (to grow). Concrete floors were found in the royal palace of Tiryns , Greece, which dates roughly to 1400 to 1200 BC. Lime mortars were used in Greece, such as in Crete and Cyprus, in 800 BC. The Assyrian Jerwan Aqueduct (688 BC) made use of waterproof concrete . Concrete

2331-554: The interlinking of the silicates and aluminate components as well as their bonding to sand and gravel particles to form a solid mass. One illustrative conversion is the hydration of tricalcium silicate: The hydration (curing) of cement is irreversible. Fine and coarse aggregates make up the bulk of a concrete mixture. Sand , natural gravel, and crushed stone are used mainly for this purpose. Recycled aggregates (from construction, demolition, and excavation waste) are increasingly used as partial replacements for natural aggregates, while

2394-550: The interview with Rolf Fehlbaum, there was an interest in the style of product design, like that of Charles and Ray Eames. To economically accomplish the project, Hadid used just a few poured-in-place concrete slabs for the connections to the planar structure. Danish architect Bjarke Ingels described Hadid's work with the building: She had somehow found a way to manifest in physical form the seemingly impossible perspectives of floating elements and skewed angles that she had captured in her fantasy [paintings]. There were reports that

2457-406: The making of mortar. In an English translation from 1397, it reads "lyme ... is a stone brent; by medlynge thereof with sonde and water sement is made". From the 14th century, the quality of mortar was again excellent, but only from the 17th century was pozzolana commonly added. The Canal du Midi was built using concrete in 1670. Perhaps the greatest step forward in the modern use of concrete

2520-531: The material. Mineral admixtures use recycled materials as concrete ingredients. Conspicuous materials include fly ash , a by-product of coal-fired power plants ; ground granulated blast furnace slag , a by-product of steelmaking ; and silica fume , a by-product of industrial electric arc furnaces . Structures employing Portland cement concrete usually include steel reinforcement because this type of concrete can be formulated with high compressive strength , but always has lower tensile strength . Therefore, it

2583-419: The mix, are being tested and used. These developments are ever growing in relevance to minimize the impacts caused by cement use, notorious for being one of the largest producers (at about 5 to 10%) of global greenhouse gas emissions . The use of alternative materials also is capable of lowering costs, improving concrete properties, and recycling wastes, the latest being relevant for circular economy aspects of

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2646-478: The mixed concrete, often to a concrete mixer truck. Modern concrete is usually prepared as a viscous fluid, so that it may be poured into forms. The forms are containers that define the desired shape. Concrete formwork can be prepared in several ways, such as slip forming and steel plate construction . Alternatively, concrete can be mixed into dryer, non-fluid forms and used in factory settings to manufacture precast concrete products. Interruption in pouring

2709-441: The mixing of cement and water into a paste before combining these materials with aggregates can increase the compressive strength of the resulting concrete. The paste is generally mixed in a high-speed , shear-type mixer at a w/c (water to cement ratio) of 0.30 to 0.45 by mass. The cement paste premix may include admixtures such as accelerators or retarders, superplasticizers , pigments , or silica fume . The premixed paste

2772-441: The mixture to improve the physical properties of the wet mix, delay or accelerate the curing time, or otherwise change the finished material. Most concrete is poured with reinforcing materials (such as steel rebar ) embedded to provide tensile strength , yielding reinforced concrete . In the past, lime -based cement binders, such as lime putty, were often used but sometimes with other hydraulic cements , (water resistant) such as

2835-506: The properties or increase the performance envelope of the mix. Design-mix concrete can have very broad specifications that cannot be met with more basic nominal mixes, but the involvement of the engineer often increases the cost of the concrete mix. Concrete mixes are primarily divided into nominal mix, standard mix and design mix. Nominal mix ratios are given in volume of Cement : Sand : Aggregate {\displaystyle {\text{Cement : Sand : Aggregate}}} . Nominal mixes are

2898-468: The quality and nature of the product. Design mix ratios are decided by an engineer after analyzing the properties of the specific ingredients being used. Instead of using a 'nominal mix' of 1 part cement, 2 parts sand, and 4 parts aggregate (the second example from above), a civil engineer will custom-design a concrete mix to exactly meet the requirements of the site and conditions, setting material ratios and often designing an admixture package to fine-tune

2961-477: The reaction takes the form of electromagnetic energy or kinetic energy of molecules. The transition of electrons from one quantum energy level to another causes light to be released. This light is equivalent in energy to some of the stabilization energy of the energy for the chemical reaction, i.e. the bond energy . This light that is released can be absorbed by other molecules in solution to give rise to molecular translations and rotations, which gives rise to

3024-411: The strength of the concrete bonding to resist tension. The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic (volcanic) rock and ash, whereby the crystallization of strätlingite (a specific and complex calcium aluminosilicate hydrate) and the coalescence of this and similar calcium–aluminium-silicate–hydrate cementing binders helped give the concrete

3087-464: The sun and use it in an endothermic, otherwise non-spontaneous process. The chemical energy stored can be freed by the inverse (spontaneous) process: combustion of sugar, which gives carbon dioxide, water and heat (radiant energy). Exothermic refers to a transformation in which a closed system releases energy (heat) to the surroundings, expressed by When the transformation occurs at constant pressure and without exchange of electrical energy , heat Q

3150-497: The surface of concrete for a decorative "exposed aggregate" finish, popular among landscape designers. Admixtures are materials in the form of powder or fluids that are added to the concrete to give it certain characteristics not obtainable with plain concrete mixes. Admixtures are defined as additions "made as the concrete mix is being prepared". The most common admixtures are retarders and accelerators. In normal use, admixture dosages are less than 5% by mass of cement and are added to

3213-535: The surfaces of the aggregate together, and is typically the most expensive component. Thus, variation in sizes of the aggregate reduces the cost of concrete. The aggregate is nearly always stronger than the binder, so its use does not negatively affect the strength of the concrete. Redistribution of aggregates after compaction often creates non-homogeneity due to the influence of vibration. This can lead to strength gradients. Decorative stones such as quartzite , small river stones or crushed glass are sometimes added to

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3276-473: The system to its surroundings , usually in the form of heat , but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen). The term exothermic was first coined by 19th-century French chemist Marcellin Berthelot . The opposite of an exothermic process is an endothermic process, one that absorbs energy, usually in

3339-441: The system. An example of an endothermic reaction is a first aid cold pack, in which the reaction of two chemicals, or dissolving of one in another, requires calories from the surroundings, and the reaction cools the pouch and surroundings by absorbing heat from them. Photosynthesis , the process that allows plants to convert carbon dioxide and water to sugar and oxygen, is an endothermic process: plants absorb radiant energy from

3402-655: The various ingredients used to produce a given quantity of concrete, the cement is the most energetically expensive. Even complex and efficient kilns require 3.3 to 3.6 gigajoules of energy to produce a ton of clinker and then grind it into cement . Many kilns can be fueled with difficult-to-dispose-of wastes, the most common being used tires. The extremely high temperatures and long periods of time at those temperatures allows cement kilns to efficiently and completely burn even difficult-to-use fuels. The five major compounds of calcium silicates and aluminates comprising Portland cement range from 5 to 50% in weight. Combining water with

3465-439: The water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. Changes in gradation can also affect workability of the concrete, although a wide range of gradation can be used for various applications. An undesirable gradation can mean using

3528-527: The water through a process called concrete hydration that hardens it over several hours to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed. The hydration process is exothermic , which means ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans or superplasticizers ) are included in

3591-524: Was Smeaton's Tower , built by British engineer John Smeaton in Devon , England, between 1756 and 1759. This third Eddystone Lighthouse pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. A method for producing Portland cement was developed in England and patented by Joseph Aspdin in 1824. Aspdin chose the name for its similarity to Portland stone , which

3654-626: Was built largely of concrete, and the Pantheon has the world's largest unreinforced concrete dome. Concrete, as the Romans knew it, was a new and revolutionary material. Laid in the shape of arches , vaults and domes , it quickly hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete (c. 200 kg/cm  [20 MPa; 2,800 psi]). However, due to

3717-602: Was greatly reduced. Low kiln temperatures in the burning of lime, lack of pozzolana, and poor mixing all contributed to a decline in the quality of concrete and mortar. From the 11th century, the increased use of stone in church and castle construction led to an increased demand for mortar. Quality began to improve in the 12th century through better grinding and sieving. Medieval lime mortars and concretes were non-hydraulic and were used for binding masonry, "hearting" (binding rubble masonry cores) and foundations. Bartholomaeus Anglicus in his De proprietatibus rerum (1240) describes

3780-452: Was made from quicklime , pozzolana and an aggregate of pumice . Its widespread use in many Roman structures , a key event in the history of architecture termed the Roman architectural revolution , freed Roman construction from the restrictions of stone and brick materials. It enabled revolutionary new designs in terms of both structural complexity and dimension. The Colosseum in Rome

3843-498: Was pioneered by the Nabatean traders who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan from the 4th century BC. They discovered the advantages of hydraulic lime , with some self-cementing properties, by 700 BC. They built kilns to supply mortar for the construction of rubble masonry houses, concrete floors, and underground waterproof cisterns . They kept

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3906-622: Was quarried on the Isle of Portland in Dorset , England. His son William continued developments into the 1840s, earning him recognition for the development of "modern" Portland cement. Reinforced concrete was invented in 1849 by Joseph Monier . and the first reinforced concrete house was built by François Coignet in 1853. The first concrete reinforced bridge was designed and built by Joseph Monier in 1875. Prestressed concrete and post-tensioned concrete were pioneered by Eugène Freyssinet ,

3969-625: Was used for construction in many ancient structures. Mayan concrete at the ruins of Uxmal (AD 850–925) is referenced in Incidents of Travel in the Yucatán by John L. Stephens . "The roof is flat and had been covered with cement". "The floors were cement, in some places hard, but, by long exposure, broken, and now crumbling under the feet." "But throughout the wall was solid, and consisting of large stones imbedded in mortar, almost as hard as rock." Small-scale production of concrete-like materials

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