Concret "concret" auf Deutsch
Englisch-Deutsch-Übersetzungen für concrete im Online-Wörterbuch nodesim.eu (Deutschwörterbuch). Lernen Sie die Übersetzung für 'concrete' in LEOs Englisch ⇔ Deutsch Wörterbuch. Mit Flexionstabellen der verschiedenen Fälle und Zeiten ✓ Aussprache. Zertifizierung von Qualitätsmanagement-Systemen in Akut-Spitälern, Pflegeheimen, Rehabilitationskliniken und Spitex-Organisationen. concret (-ète) [kɔ͂kʀɛ, -ɛt] ADJ. concret (-ète). konkret. Übersetzung im Kontext von „concret“ in Englisch-Deutsch von Reverso Context: It has a ranch with concret table and benches, and has a small pool for. Concrete (englisch für Beton) steht für: Concrete (Album), Musikalbum der Pet Shop Boys. Orte in den Vereinigten Staaten: Concrete (Colorado) · Concrete. The floors in the car park consist of concrete. — Die Böden in dem Parkhaus bestehen aus Beton. I will wait until the concrete has firmed.
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Will such projections really provide the only justification for concreting over our green spaces? DE Erfüllung Konkretisierung. Die konkrete Geschichte beginnt eigentlich im Jahrauch wenn Katzen schon immer Plum Blossom Leben meiner Hatefull Eight und mir bestimmten. Bitte versuchen Sie es erneut. Türkisch Wörterbücher. Wörterbuch Apps. Der Preis beinhaltet den jetztigen Bauzustand, die Bauerschliessungskosten sowie die Projektgebühren. We have all seen central grassed or hedge lanes of motorways being Ksenia Solo over. French solidifier coaguler condenser congeler consolider durcir geler raffermir renforcer. Die astralen Ebenen sind sehr viel "dünner" oder "feinstofflicher" als der Äther, die elektromagnetische Kraft erscheint Bruce Willis Deutsch diesen Ebenen greifbar und fest. Synonyme Synonyme Französisch für "concret":.Raw concrete surfaces tend to be porous and have a relatively uninteresting appearance. Many finishes can be applied to improve the appearance and preserve the surface against staining, water penetration, and freezing.
Examples of improved appearance include stamped concrete where the wet concrete has a pattern impressed on the surface, to give a paved, cobbled or brick-like effect, and may be accompanied with coloration.
Another popular effect for flooring and table tops is polished concrete where the concrete is polished optically flat with diamond abrasives and sealed with polymers or other sealants.
Other finishes can be achieved with chiseling, or more conventional techniques such as painting or covering it with other materials.
The proper treatment of the surface of concrete, and therefore its characteristics, is an important stage in the construction and renovation of architectural structures.
Prestressed concrete is a form of reinforced concrete that builds in compressive stresses during construction to oppose tensile stresses experienced in use.
This can greatly reduce the weight of beams or slabs, by better distributing the stresses in the structure to make optimal use of the reinforcement.
For example, a horizontal beam tends to sag. Prestressed reinforcement along the bottom of the beam counteracts this. In pre-tensioned concrete, the prestressing is achieved by using steel or polymer tendons or bars that are subjected to a tensile force prior to casting, or for post-tensioned concrete, after casting.
Reinforced concrete , prestressed concrete and precast concrete are the most widely used types of concrete functional extensions in modern days.
See Brutalism. Extreme weather conditions extreme heat or cold; windy condition, and humidity variations can significantly alter the quality of concrete.
Many precautions are observed in cold weather placement. Preventing freezing is the most important precaution, as formation of ice crystals can cause damage to the crystalline structure of the hydrated cement paste.
If the surface of the concrete pour is insulated from the outside temperatures, the heat of hydration will prevent freezing. In Canada , where temperatures tend to be much lower during the cold season, the following criteria are used by CSA A The minimum strength before exposing concrete to extreme cold is psi 3.
CSA A Concrete may be placed and cured underwater. Care must be taken in the placement method to prevent washing out the cement. Underwater placement methods include the tremie , pumping, skip placement, manual placement using toggle bags, and bagwork.
Grouted aggregate is an alternative method of forming a concrete mass underwater, where the forms are filled with coarse aggregate and the voids then completely filled with pumped grout.
Concrete roads are more fuel efficient to drive on, [92] more reflective and last significantly longer than other paving surfaces, yet have a much smaller market share than other paving solutions.
Modern-paving methods and design practices have changed the economics of concrete paving, so that a well-designed and placed concrete pavement will be less expensive on initial costs and significantly less expensive over the life cycle.
Another major benefit is that pervious concrete can be used, which eliminates the need to place storm drains near the road, and reducing the need for slightly sloped roadway to help rainwater to run off.
No longer requiring discarding rainwater through use of drains also means that less electricity is needed more pumping is otherwise needed in the water-distribution system , and no rainwater gets polluted as it no longer mixes with polluted water.
Rather, it is immediately absorbed by the ground. Energy requirements for transportation of concrete are low because it is produced locally from local resources, typically manufactured within kilometers of the job site.
Similarly, relatively little energy is used in producing and combining the raw materials although large amounts of CO 2 are produced by the chemical reactions in cement manufacture.
Once in place, concrete offers great energy efficiency over the lifetime of a building. The thermal mass properties of concrete increase the efficiency of both residential and commercial buildings.
By storing and releasing the energy needed for heating or cooling, concrete's thermal mass delivers year-round benefits by reducing temperature swings inside and minimizing heating and cooling costs.
Modern concrete wall systems use both external insulation and thermal mass to create an energy-efficient building. Insulating concrete forms ICFs are hollow blocks or panels made of either insulating foam or rastra that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.
Concrete buildings are more resistant to fire than those constructed using steel frames, since concrete has lower heat conductivity than steel and can thus last longer under the same fire conditions.
Concrete is sometimes used as a fire protection for steel frames, for the same effect as above. Concrete as a fire shield, for example Fondu fyre , can also be used in extreme environments like a missile launch pad.
Options for non-combustible construction include floors, ceilings and roofs made of cast-in-place and hollow-core precast concrete. ICFs are hollow blocks or panels made of fireproof insulating foam that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.
Concrete also provides good resistance against externally applied forces such as high winds, hurricanes, and tornadoes owing to its lateral stiffness, which results in minimal horizontal movement.
However, this stiffness can work against certain types of concrete structures, particularly where a relatively higher flexing structure is required to resist more extreme forces.
As discussed above, concrete is very strong in compression, but weak in tension. Larger earthquakes can generate very large shear loads on structures.
These shear loads subject the structure to both tensile and compressional loads. Concrete structures without reinforcement, like other unreinforced masonry structures, can fail during severe earthquake shaking.
Unreinforced masonry structures constitute one of the largest earthquake risks globally. Concrete can be damaged by many processes, such as the expansion of corrosion products of the steel reinforcement bars , freezing of trapped water, fire or radiant heat, aggregate expansion, sea water effects, bacterial corrosion, leaching, erosion by fast-flowing water, physical damage and chemical damage from carbonatation , chlorides, sulfates and distillate water.
The manufacture and use of concrete produce a wide range of environmental and social consequences. Some are harmful, some welcome, and some both, depending on circumstances.
A major component of concrete is cement , which similarly exerts environmental and social effects. Every tonne of cement produced releases one tonne of CO 2 into the atmosphere.
Concrete is used to create hard surfaces that contribute to surface runoff , which can cause heavy soil erosion, water pollution, and flooding, but conversely can be used to divert, dam, and control flooding.
Concrete dust released by building demolition and natural disasters can be a major source of dangerous air pollution. Concrete is a contributor to the urban heat island effect, though less so than asphalt.
Workers who cut, grind or polish concrete are at risk of inhaling airborne silica, which can lead to silicosis. The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and radioactivity.
Fresh concrete before curing is complete is highly alkaline and must be handled with proper protective equipment.
Concrete recycling is an increasingly common method for disposing of concrete structures. Concrete debris was once routinely shipped to landfills for disposal, but recycling is increasing due to improved environmental awareness, governmental laws and economic benefits.
The amount of concrete used in the construction of the dam is estimated at 16 million cubic meters over 17 years.
The previous record was The Polavaram dam works in Andhra Pradesh on 6 January entered the Guinness World Records by pouring 32, cubic metres of concrete in 24 hours.
The record for the largest continuously placed underwater concrete pour was completed 18 October , in New Orleans, Louisiana by contractor C.
The placement consisted of 10, cubic yards of concrete placed in From Wikipedia, the free encyclopedia. Composite construction material. This article is about the construction material.
For other uses, see Concrete disambiguation. Not to be confused with cement , grout , mortar masonry , or plaster.
Main article: Cement. Main article: Construction aggregate. Main article: Reinforced concrete. See also: Volumetric concrete mixer and Concrete mixer.
Main article: Concrete slump test. Main article: Types of concrete. Main article: asphalt concrete. Main article: Pervious concrete.
Main article: Polymer concrete. Main article: Properties of concrete. Main article: Mass concrete. Main article: Decorative concrete.
Main article: Prestressed concrete. Main article: Concrete degradation. Main article: Environmental impact of concrete. Main article: Concrete recycling.
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Retrieved 19 June Retrieved 17 August United States Environmental Protection Agency. Journal of Occupational and Environmental Hygiene. Archived PDF from the original on 8 April Retrieved 14 June Archived from the original on 9 February Retrieved 2 January Retrieved 28 March All aggregate materials must be clean and free from admixture with soft particles or vegetable matter, because even small quantities of organic soil compounds result in chemical reactions that seriously affect the strength of the concrete.
Concrete is characterized by the type of aggregate or cement used, by the specific qualities it manifests , or by the methods used to produce it.
In ordinary structural concrete, the character of the concrete is largely determined by a water-to-cement ratio.
The lower the water content, all else being equal, the stronger the concrete. The mixture must have just enough water to ensure that each aggregate particle is completely surrounded by the cement paste, that the spaces between the aggregate are filled, and that the concrete is liquid enough to be poured and spread effectively.
Another durability factor is the amount of cement in relation to the aggregate expressed as a three-part ratio—cement to fine aggregate to coarse aggregate.
Where especially strong concrete is needed, there will be relatively less aggregate. The strength of concrete is measured in pounds per square inch or kilograms per square centimetre of force needed to crush a sample of a given age or hardness.
If it is allowed to dry prematurely, it can experience unequal tensile stresses that in an imperfectly hardened state cannot be resisted.
In the process known as curing, the concrete is kept damp for some time after pouring to slow the shrinkage that occurs as it hardens. Low temperatures also adversely affect its strength.
To compensate for this, an additive such as calcium chloride is mixed in with the cement. This accelerates the setting process, which in turn generates heat sufficient to counteract moderately low temperatures.
Large concrete forms that cannot be adequately covered are not poured in freezing temperatures. Concrete that has been hardened onto imbedded metal usually steel is called reinforced concrete , or ferroconcrete.
Its invention is usually attributed to Joseph Monier , a Parisian gardener who made garden pots and tubs of concrete reinforced with iron mesh; he received a patent in The reinforcing steel , which may take the form of rods, bars, or mesh, contributes tensile strength.
Plain concrete does not easily withstand stresses such as wind action, earthquakes, and vibrations and other bending forces and is therefore unsuitable in many structural applications.
In reinforced concrete, the tensile strength of steel and the compressional strength of concrete render a member capable of sustaining heavy stresses of all kinds over considerable spans.
The fluidity of the concrete mix makes it possible to position the steel at or near the point where the greatest stress is anticipated. Another innovation in masonry construction is the use of prestressed concrete.
It is achieved by either pretensioning or posttensioning processes. In pretensioning, lengths of steel wire, cables, or ropes are laid in the empty mold and then stretched and anchored.
After the concrete has been poured and allowed to set, the anchors are released and, as the steel seeks to return to its original length, it compresses the concrete.
In the posttensioning process, the steel is run through ducts formed in the concrete. When the concrete has hardened, the steel is anchored to the exterior of the member by some sort of gripping device.
By applying a measured amount of stretching force to the steel, the amount of compression transmitted to the concrete can be carefully regulated.
Prestressed concrete neutralizes the stretching forces that would rupture ordinary concrete by compressing an area to the point at which no tension is experienced until the strength of the compressed section is overcome.
Because it achieves strength without using heavy steel reinforcements, it has been used to great effect to build lighter, shallower, and more elegant structures such as bridges and vast roofs.
In addition to its potential for immense strength and its initial ability to adapt to virtually any form, concrete is fire resistant and has become one of the most common building materials in the world.
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A central-mix plant offers more accurate control of the concrete quality through Concret measurements Michael Bully Herbig the amount of water added, Kinder Filme Online Stream must be placed closer to the work site where the concrete will be used, since hydration begins at the plant. Archived from the Romeo And Juliet Film on 15 September Concret The Egyptians developed a substance more closely resembling modern concrete by using lime and gypsum Mord Im Orientexpress Stream binders. Archived from the original on 15 May McGraw-Hill Education. Ancient Roman architecture Roman architectural revolution Roman concrete Roman engineering Roman technology. For cementitious binders, water is mixed with Franz Drameh dry powder and aggregate, which produces a semi-liquid slurry that can be shaped, typically by pouring it into a form.
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Usage explanations of natural written and spoken English. Clear explanations of natural written and spoken English. Dieses Verb konjugieren. Was ist die Aussprache von concrete? We have not 50 Erste Dates Ganzer Film Deutsch received a concrete proposal. The bomb shelter has concrete walls that are three metres thick. DE konkret. concrete Bedeutung, Definition concrete: 1. a very hard building material made by mixing together cement, sand, small stones, and water: 2. „concret“: adjectif (qualificatif). concret. [kõkʀɛ]adjectif (qualificatif) | Adjektiv adj. concrète {Adjektiv Feminin}. volume_up. volume_up. praxisorientiert {Adj.} concrète (auch: concret).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 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 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. Redistribution of aggregates after compaction often creates inhomogeneity 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 the surface of concrete for a decorative "exposed aggregate" finish, popular among landscape designers.
Concrete is strong in compression , as the aggregate efficiently carries the compression load. However, it is weak in tension as the cement holding the aggregate in place can crack, allowing the structure to fail.
Reinforced concrete adds either steel reinforcing bars , steel fibers , aramid fibers, carbon fibers , glass fibers , or plastic fibers to carry tensile loads.
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 common types of admixtures [45] 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 , [44] or as a replacement for Portland cement blended cements.
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 a large type of industrial facility called a concrete plant , or often a batch plant.
In general usage, concrete plants come in two main types, ready mix plants and central mix plants.
A ready-mix plant mixes all the ingredients except water, while a central mix plant mixes all the ingredients including water.
A central-mix plant offers more accurate control of the concrete quality through better measurements of the amount of water added, but must be placed closer to the work site where the concrete will be used, since hydration begins at the plant.
A concrete plant consists of large storage hoppers for various reactive 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 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, which are containers erected in the field to give the concrete its 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.
A wide variety of equipment is used for processing concrete, from hand tools to heavy industrial machinery. Whichever equipment builders use, however, the objective is to produce the desired building material; ingredients must be properly mixed, placed, shaped, and retained within time constraints.
Any interruption in pouring 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. During concrete preparation, various technical details may affect the quality and nature of the product.
Separate paste mixing has shown that 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 cement paste premix may include admixtures such as accelerators or retarders, superplasticizers , pigments , or silica fume. The premixed paste is then blended with aggregates and any remaining batch water and final mixing is completed in conventional concrete mixing equipment.
Nominal mixes are 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 day cube strength. 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 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.
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 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.
The use of an aggregate blend with an undesirable gradation [ citation needed ] can result in a very harsh mix design with a very low slump, which cannot readily be made more workable by addition of reasonable amounts of water.
An undesirable gradation can mean using 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 a mix which is too harsh, i. Workability can be measured by the concrete slump test , a simple measure of the plasticity of a fresh batch of concrete following the ASTM C or EN test standards.
Slump is normally measured by filling an " Abrams cone " with a sample from a fresh batch of concrete.
The cone is placed with the wide end down onto a level, non-absorptive surface. It is then filled in three layers of equal volume, with each layer being tamped with a steel rod to consolidate the layer.
When the cone is carefully lifted off, the enclosed material slumps a certain amount, owing to gravity. A relatively wet concrete sample may slump as much as eight inches.
Workability can also be measured by the flow table test. Slump can be increased by addition of chemical admixtures such as plasticizer or superplasticizer without changing the water-cement ratio.
High-flow concrete, like self-consolidating concrete , is tested by other flow-measuring methods. One of these methods includes placing the cone on the narrow end and observing how the mix flows through the cone while it is gradually lifted.
Concrete must be kept moist during curing in order to achieve optimal strength and durability. This carbonation reaction, however, lowers the pH of the cement pore solution and can corrode the reinforcement bars.
Hydration and hardening of concrete during the first three days is critical. Abnormally fast drying and shrinkage due to factors such as evaporation from wind during placement may lead to increased tensile stresses at a time when it has not yet gained sufficient strength, resulting in greater shrinkage cracking.
The early strength of the concrete can be increased if it is kept damp during the curing process. Minimizing stress prior to curing minimizes cracking.
High-early-strength concrete is designed to hydrate faster, often by increased use of cement that increases shrinkage and cracking. The strength of concrete changes increases for up to three years.
It depends on cross-section dimension of elements and conditions of structure exploitation. Properly curing concrete leads to increased strength and lower permeability and avoids cracking where the surface dries out prematurely.
Care must also be taken to avoid freezing or overheating due to the exothermic setting of cement.
Improper curing can cause scaling , reduced strength, poor abrasion resistance and cracking. During the curing period, concrete is ideally maintained at controlled temperature and humidity.
To ensure full hydration during curing, concrete slabs are often sprayed with "curing compounds" that create a water-retaining film over the concrete.
Typical films are made of wax or related hydrophobic compounds. After the concrete is sufficiently cured, the film is allowed to abrade from the concrete through normal use.
Traditional conditions for curing involve spraying or ponding the concrete surface with water. The adjacent picture shows one of many ways to achieve this, ponding—submerging setting concrete in water and wrapping in plastic to prevent dehydration.
Additional common curing methods include wet burlap and plastic sheeting covering the fresh concrete.
For higher-strength applications, accelerated curing techniques may be applied to the concrete. A common technique involves heating the poured concrete with steam, which serves to both keep it damp and raise the temperature, so that the hydration process proceeds more quickly and more thoroughly.
Asphalt concrete commonly called asphalt , [67] blacktop , or pavement in North America, and tarmac , bitumen macadam , or rolled asphalt in the United Kingdom and the Republic of Ireland is a composite material commonly used to surface roads , parking lots , airports , as well as the core of embankment dams.
The process was refined and enhanced by Belgian inventor and U. The terms asphalt or asphaltic concrete , bituminous asphalt concrete , and bituminous mixture are typically used only in engineering and construction documents, which define concrete as any composite material composed of mineral aggregate adhered with a binder.
The abbreviation, AC , is sometimes used for asphalt concrete but can also denote asphalt content or asphalt cement , referring to the liquid asphalt portion of the composite material.
Pervious concrete is a mix of specially graded coarse aggregate, cement, water and little-to-no fine aggregates. This concrete is also known as "no-fines" or porous concrete.
Mixing the ingredients in a carefully controlled process creates a paste that coats and bonds the aggregate particles. The hardened concrete contains interconnected air voids totaling approximately 15 to 25 percent.
Water runs through the voids in the pavement to the soil underneath. Air entrainment admixtures are often used in freeze—thaw climates to minimize the possibility of frost damage.
Pervious concrete also permits rainwater to filter through roads and parking lots, to recharge aquifers, instead of contributing to runoff and flooding.
Bacteria such as Bacillus pasteurii , Bacillus pseudofirmus , Bacillus cohnii , Sporosarcina pasteuri , and Arthrobacter crystallopoietes increase the compression strength of concrete through their biomass.
Not all bacteria increase the strength of concrete significantly with their biomass. Sporosarcina pasteurii reduces water and chloride permeability.
Polymer concretes are mixtures of aggregate and any of various polymers and may be reinforced. The cement is costlier than lime-based cements, but polymer concretes nevertheless have advantages; they have significant tensile strength even without reinforcement, and they are largely impervious to water.
Polymer concretes are frequently used for repair and construction of other applications, such as drains. Grinding of concrete can produce hazardous dust.
Exposure to cement dust can lead to issues such as silicosis , kidney disease, skin irritation and similar effects. The U. National Institute for Occupational Safety and Health in the United States recommends attaching local exhaust ventilation shrouds to electric concrete grinders to control the spread of this dust.
An updated silica rule, [78] which OSHA put into effect 23 September for construction companies, restricted the amount of respirable crystalline silica workers could legally come into contact with to 50 micrograms per cubic meter of air per 8-hour workday.
That same rule went into effect 23 June for general industry, hydraulic fracturing and maritime. That the deadline was extended to 23 June for engineering controls in the hydraulic fracturing industry.
Companies which fail to meet the tightened safety regulations can face financial charges and extensive penalties. Concrete has relatively high compressive strength , but much lower tensile strength.
The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops.
Concrete has a very low coefficient of thermal expansion and shrinks as it matures. All concrete structures crack to some extent, due to shrinkage and tension.
Concrete that is subjected to long-duration forces is prone to creep. Tests can be performed to ensure that the properties of concrete correspond to specifications for the application.
The ingredients affect the strengths of the material. Concrete strength values are usually specified as the lower-bound compressive strength of either a cylindrical or cubic specimen as determined by standard test procedures.
The strengths of concrete is dictated by its function. Higher-strength concrete is often used for larger civil projects.
Bridges may use long beams of high-strength concrete to lower the number of spans required. If a structure must be very rigid, concrete of very high strength may be specified, even much stronger than is required to bear the service loads.
Concrete is one of the most durable building materials. It provides superior fire resistance compared with wooden construction and gains strength over time.
Structures made of concrete can have a long service life. Due to cement's exothermic chemical reaction while setting up, large concrete structures such as dams , navigation locks , large mat foundations, and large breakwaters generate excessive heat during hydration and associated expansion.
To mitigate these effects, post-cooling [87] is commonly applied during construction. An early example at Hoover Dam used a network of pipes between vertical concrete placements to circulate cooling water during the curing process to avoid damaging overheating.
Similar systems are still used; depending on volume of the pour, the concrete mix used, and ambient air temperature, the cooling process may last for many months after the concrete is placed.
Various methods also are used to pre-cool the concrete mix in mass concrete structures. Another approach to mass concrete structures that minimizes cement's thermal byproduct is the use of roller-compacted concrete , which uses a dry mix which has a much lower cooling requirement than conventional wet placement.
It is deposited in thick layers as a semi-dry material then roller compacted into a dense, strong mass. Advantage and Disadvantage of Concrete. Raw concrete surfaces tend to be porous and have a relatively uninteresting appearance.
Many finishes can be applied to improve the appearance and preserve the surface against staining, water penetration, and freezing.
Examples of improved appearance include stamped concrete where the wet concrete has a pattern impressed on the surface, to give a paved, cobbled or brick-like effect, and may be accompanied with coloration.
Another popular effect for flooring and table tops is polished concrete where the concrete is polished optically flat with diamond abrasives and sealed with polymers or other sealants.
Other finishes can be achieved with chiseling, or more conventional techniques such as painting or covering it with other materials.
The proper treatment of the surface of concrete, and therefore its characteristics, is an important stage in the construction and renovation of architectural structures.
Prestressed concrete is a form of reinforced concrete that builds in compressive stresses during construction to oppose tensile stresses experienced in use.
This can greatly reduce the weight of beams or slabs, by better distributing the stresses in the structure to make optimal use of the reinforcement.
For example, a horizontal beam tends to sag. Prestressed reinforcement along the bottom of the beam counteracts this.
In pre-tensioned concrete, the prestressing is achieved by using steel or polymer tendons or bars that are subjected to a tensile force prior to casting, or for post-tensioned concrete, after casting.
Reinforced concrete , prestressed concrete and precast concrete are the most widely used types of concrete functional extensions in modern days.
See Brutalism. Extreme weather conditions extreme heat or cold; windy condition, and humidity variations can significantly alter the quality of concrete.
Many precautions are observed in cold weather placement. Preventing freezing is the most important precaution, as formation of ice crystals can cause damage to the crystalline structure of the hydrated cement paste.
If the surface of the concrete pour is insulated from the outside temperatures, the heat of hydration will prevent freezing.
In Canada , where temperatures tend to be much lower during the cold season, the following criteria are used by CSA A The minimum strength before exposing concrete to extreme cold is psi 3.
CSA A Concrete may be placed and cured underwater. Care must be taken in the placement method to prevent washing out the cement. Underwater placement methods include the tremie , pumping, skip placement, manual placement using toggle bags, and bagwork.
Grouted aggregate is an alternative method of forming a concrete mass underwater, where the forms are filled with coarse aggregate and the voids then completely filled with pumped grout.
Concrete roads are more fuel efficient to drive on, [92] more reflective and last significantly longer than other paving surfaces, yet have a much smaller market share than other paving solutions.
Modern-paving methods and design practices have changed the economics of concrete paving, so that a well-designed and placed concrete pavement will be less expensive on initial costs and significantly less expensive over the life cycle.
Another major benefit is that pervious concrete can be used, which eliminates the need to place storm drains near the road, and reducing the need for slightly sloped roadway to help rainwater to run off.
No longer requiring discarding rainwater through use of drains also means that less electricity is needed more pumping is otherwise needed in the water-distribution system , and no rainwater gets polluted as it no longer mixes with polluted water.
Rather, it is immediately absorbed by the ground. Its invention is usually attributed to Joseph Monier , a Parisian gardener who made garden pots and tubs of concrete reinforced with iron mesh; he received a patent in The reinforcing steel , which may take the form of rods, bars, or mesh, contributes tensile strength.
Plain concrete does not easily withstand stresses such as wind action, earthquakes, and vibrations and other bending forces and is therefore unsuitable in many structural applications.
In reinforced concrete, the tensile strength of steel and the compressional strength of concrete render a member capable of sustaining heavy stresses of all kinds over considerable spans.
The fluidity of the concrete mix makes it possible to position the steel at or near the point where the greatest stress is anticipated.
Another innovation in masonry construction is the use of prestressed concrete. It is achieved by either pretensioning or posttensioning processes.
In pretensioning, lengths of steel wire, cables, or ropes are laid in the empty mold and then stretched and anchored. After the concrete has been poured and allowed to set, the anchors are released and, as the steel seeks to return to its original length, it compresses the concrete.
In the posttensioning process, the steel is run through ducts formed in the concrete. When the concrete has hardened, the steel is anchored to the exterior of the member by some sort of gripping device.
By applying a measured amount of stretching force to the steel, the amount of compression transmitted to the concrete can be carefully regulated.
Prestressed concrete neutralizes the stretching forces that would rupture ordinary concrete by compressing an area to the point at which no tension is experienced until the strength of the compressed section is overcome.
Because it achieves strength without using heavy steel reinforcements, it has been used to great effect to build lighter, shallower, and more elegant structures such as bridges and vast roofs.
In addition to its potential for immense strength and its initial ability to adapt to virtually any form, concrete is fire resistant and has become one of the most common building materials in the world.
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Let us know if you have suggestions to improve this article requires login. When they are full, many landfills are capped—covered with asphalt or concrete.
The concrete building from which the sounds emanate shakes from the impact, rattling the colorful houses on the dirt roads nearby.
In this material and in such forms, the ideal as concrete spirituality does not admit of being realized. Shall we now give attention to some two or three concrete cases?
The average amount of concrete placed in the walls per day was 50 cu. The people need, to meet their problems, concrete information that furnishes specific answers to their difficulties.
I reject the concrete example, but accept the universal doctrine on which the special dogma of the Trinity is erected.
Compare reinforced concrete.
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