Reinforced concrete at Sainte Jeanne d'Arc Church (Nice, France): architect Jacques Dror, 1926–1933

Reinforced concrete, also called ferroconcrete in some countries, is concrete in which reinforcement bars ("rebars") or fibers have been incorporated to strengthen the material that would otherwise be brittle. Download high resolution version (512x768, 69 KB)Sainte Jeanne dArc Church Photograph available under GFDL license. ... Download high resolution version (512x768, 69 KB)Sainte Jeanne dArc Church Photograph available under GFDL license. ... Sainte Jeanne dArc at night Sainte Jeanne dArc is a Catholic church located in Nice, France noticeable for its original architecture. ... Pouring a concrete floor for a commercial building, (slab-on-grade) Installing rebar in a floor slab during a concrete pour For other uses, see Concrete (disambiguation). ... A tied rebar beam cage. ...

History

The use of reinforced concrete is a relatively recent invention, usually dated to 1848 when Jean-Louis Lambot became the first to use it. Joseph Monier, a French gardener, patented a design for reinforced garden tubs in 1868, and later patented reinforced concrete beams and posts for railway and road guardrails. Most reinforcement is made of steel, but fiber-reinforced plastic materials are available. The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... Fibre reinforced plastic (FRP) is a composite material comprising a polymer matrix reinforced with fibres usually of glass, carbon, or aramid (and in the case of Duroplast even cotton or wool) and is commonly used in aerospace, automotive and marine industries. ...

The major developments of reinforced concrete have taken place since the year 1900; and from the late 20th Century, engineers have developed sufficient confidence in a new method of reinforcing concrete, called post-tensioned concrete, to make routine use of it. 1900 (MCM) was an exceptional common year starting on Monday. ... This article or section should be merged with Prestressed concrete Post-tensioned concrete is the descriptive term for a method of reinforcing concrete by applying compression to poured concrete after the curing process (in situ). ...

Tied Rebar

Tied rebar This is my own photo, and I release it to public domain Zeizmic 20:09 26 May 2003 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Tied rebar This is my own photo, and I release it to public domain Zeizmic 20:09 26 May 2003 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... A tied rebar beam cage. ...

Physics and statics

Concrete is a mixture of portland cement and stone aggregate. Stone aggregate can be made up from small grains of sand, fist-sized rocks, or a combination of sizes. When mixed with a small amount of water, portland cement hydrates to form a microscopic opaque crystal lattice structure encapsulating and locking the aggregate into its rigid structure. Typical concrete mixes employ a washed-gravel aggregate and have extremely high resistance to downward compressive stresses (about 3,000 lb/sq in); however, any appreciable stretching or bending (tension) will break the microscopic rigid lattice resulting in cracking and separation of the concrete. For this reason, typical concrete must be supported or placed on an earth footing to prevent cracking. Sampling fast set Portland cement Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and plaster. ... Sampling fast set Portland cement Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and plaster. ... Hydrates are compounds formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts. ... Compression in material science, physics or structural engineering, is the stress state of materials where the volume tends to decrease (compaction). ... Figure 1  Stress tensor In physics, stress is a measure of the internal distribution of force per unit area within a body that balances and reacts to the loads applied to it. ... Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ...

Amazingly, if a non-stretchable material, such as steel, is included with the aggregate, the reinforced concrete is transformed into structural elements which resist stretching, bending, or other direct tensile action. A reinforced concrete section (illustration, left) where the concrete takes the compression and steel takes the tension is so efficient in carrying forces that it can be made into almost any shape and size for the construction industry.

The significance of this "additive resistance to forces" cannot be overstated. Concrete and steel are very inexpensive everyday building materials which allow the creation of very expensive structures. Depending on the type of concrete mix and steel employed, reinforced concrete structures can support 300 to 500 times their combined weight and behave, according to general mechanics, as a single structural entity. (For comparison, consider that typical student-constructed balsa wood bridges only support 20 to 80 times their weight!) Image File history File links Download high resolution version (320x602, 341 KB) Summary Ossworks, Street light made from reinforced concrete. ...

Happily, three physical characteristics come together to give reinforced concrete its special properities. First, the coefficient of thermal expansion of concrete is very nearly identical to that of steel, eliminating internal stresses due to differences in thermal expansion or contraction. Second, when cement cures, the microscopic lattice conforms to the surface details of the steel, permitting any stress to be transmitted efficiently among the different materials. Usually steel bars are roughened or corrugated to further improve the bond or cohesion between the concrete and steel. Third, the alkaline chemical environment provided by calcium carbonate (lime) causes a passivating film to form on the surface of steel, making it much more resistant to corrosion than it would be in neutral or acidic conditions. During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. ... In physics, heat is defined as energy in transit. ... In finance, a bond is a debt security, in which the issuer owes the holders a debt and is obliged to repay the principal and interest (the coupon). ... The correct title of this article is pH. The initial letter is capitalized due to technical restrictions. ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... Limey shale overlaid by limestone. ... Passivation is the process of making a material passive in relation to another material prior to using the materials together. ... Corrosion, atmospheric and biologic (Barnacles) Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ...

Although the ridges on rebar offer increased surface area to resist tension forces, sometimes there is not enough embedment of reinforcing steel in the concrete to fully transfer tensile forces between the concrete and rebar. For example, it is possible to pull a rebar rod from cured concrete. In cases where there would be extreme tension forces, the rebar may be bent into a 180 degree hook, which itself will transfer half of the capacity of the rebar to resist tension forces to the concrete. Area is a physical quantity expressing the size of a part of a surface. ...

In some structural members where minimum cross-section is desired, steel may be used to carry some of the compressive load as well as tensile load. This occurs in columns. Continuous beams in buildings generally require some compressive steel at the columns, but beams and slabs usually have reinforcing steel only on the tension (bottom) side. In the case of continuous girders where the tensile stress alternates between top and bottom of the member, multiple runs (layers) of steel may be used or the steel may be bent into a zig-zag shape within the beam. Deconstructing a Roman pillar. ...

The relative amount of steel required for typical strengthing is usually quite small and varyies from 1% for most beams and slabs to 6% for some columns (based on the area of a cross section of the member). Reinforcing bars are round and vary by eighths of an inch from 0.25 in to 1 in diameter (in Europe from 8 to 30 mm in steps of 2 mm). Interestingly, there does not appear to be specialized rules for the placement, pattern, or joining of rebar (other than it should be placed towards the side where the tension forces will be the strongest). In conservative construction projects like roadways and bridges, a series of rebar curtains or matrixes are embedded in the concrete. Rebar comes in two grades of carbon content, 60 and 40, which typically sell for the same price! Grade 60 has a higher carbon content and, therefore, a higher tensile strength, but its stiffness can make it difficult to bend and cut. Construction workers always prefer to use grade 40 rebar. Also galvanized rebar is available. Typically, concrete will have reached its nominal design strength at most 28 days after the water was mixed into the cement mix. Area is a physical quantity expressing the size of a part of a surface. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ... Europe is conventionally considered one of the seven continents of Earth which, in this case, is more a cultural and political distinction than a physiographic one, leading to various perspectives about Europes borders. ... A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... Galvanization refers to any of several electrochemical processes named after the Italian scientist Luigi Galvani. ...

Reinforced concrete structures sometimes have provisions such as ventilated hollow cores to control their moisture.

Corrosion and frost may damage poorly designed or constructed reinforced concrete. When rebar corrodes, the rust expands, cracking the concrete and unbonding the rebar from the concrete. Frost damage occurs when water penetrates the surface and freezes. The expansion of freezing water in microscopic cracks widens the cracks, causing flaking, and eventual structural failure. Corrosion, atmospheric and biologic (Barnacles) Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ... A blacksmith removing rust with sand prior to welding The rusting can completely eat away iron Rusted bolt Rust is the substance formed when iron compounds corrode in the presence of oxygen and water. ...

In wet and freezing climates, reinforced concrete for roads, bridges, parking structures and other structures that may be exposed to deicing salt may require epoxy-coated rebar or a well composited concrete well planes structure. Epoxy coated rebar can easily be identified by the light green color of its epoxy coating. An American Airlines MD-80 aircraft being de-iced at Syracuse Hancock International Airport De-icing is the process of removing ice from a surface. ... Epoxy or polyepoxide is a thermosetting epoxide polymer that cures (polymerizes and crosslinks) when mixed with a catalyzing agent or hardener. Most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A. The first commercial attempts to prepare resins from epichlorohydrin occurred in 1927 in the United...

Penetrating sealants must be applied some time after curing, when the concrete has dried to at least several inches of depth. One especially exotic process is to surround the cured concrete member with a vacuum bag filled with resin monomer, and then after the monomer has penetrated several inches into the concrete, the monomer is cured with a gamma ray source. This produces a very hard, attractive surface that can be dyed through the material, so chips and scratches are less visible.

Less expensive sealants include paint, plastic foams, films and aluminum foil, felts or fabric mats sealed with tar, and layers of bentonite clay, sometimes used to seal roadbeds. Aluminium foil (aluminum foil in North American English) is aluminium prepared in thin sheets (on the order of . ... Bentonite - USGS Bentonite is an absorbent aluminium phyllosilicate generally impure clay consisting mostly of montmorillonite, (Na,Ca)0. ...

Common failure modes of steel reinforced concrete

Corrosion and frost may damage poorly designed or constructed reinforced concrete. When rebar corrodes, the rust expands, cracking the concrete and unbonding the rebar from the concrete. Corrosion, atmospheric and biologic (Barnacles) Corrosion is deterioration of intrinsic properties in a material due to reactions with its environment. ... A blacksmith removing rust with sand prior to welding The rusting can completely eat away iron Rusted bolt Rust is the substance formed when iron compounds corrode in the presence of oxygen and water. ...

Carbonation

The water in the pores of the cement is normally alkaline, this alkaine environment is one in which the steel is passive and does not corrode. According to the pourbaix diagram for iron the metal is passive when pH is above 9.5.[1] The carbon dioxide from the air reacts with the alkali in the cement and makes the pore water more acidic, thus lowering the pH. Carbon dioxide will start to carbonate the cement in the concrete from the moment the object is made, this process will start at the surface and slowly move deeper and deeper into the object. If the object is cracked the carbon dioxide of the air will be more able to penitrate deep into the object. When designing a concrete structure it is normal to state the concrete cover for the rebar (the depth within the object that the rebar will be). The minimum concrete cover is normally regulated by standards or design codes. If the rebar is too close to the surface then an early failure due to corrosion may occur. Bubbles of carbon dioxide float to the surface of a carbonated soft drink. ... The common (Arrhenius) definition of a base is a chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. ... Passive has several meanings: In grammar it describes a grammatical voice. ... A Pourbaix diagram, also known as a potential/pH diagram, maps out possible stable (equilibrium) phases of an aqueous electrochemical system. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... In chemistry, an alkali (from Arabic: al-qaly) is a specific type of base, formed as a carbonate, hydroxide or other ionic salt of an alkali metal or alkali earth metal element. ...

One method of testing a structure for carbonation is to drill a fresh hole in the surface and then treat the surface with Phenolphthalein, this will turn pink when in contact with alkaline cement. It is then possible to see the depth of carbonation. An existing hole is no good as the surface will already be carbonated. A drill is a tool with a rotating drill bit used for drilling holes in various materials. ... Fresh (1994) is the debut film of writer and director Boaz Yakin. ... Rough illustration of a titration with phenol­phthalein prior to the endpoint Phenolphthalein is a sensitive pH indicator with the formula C20H14O4. ... Pink is a color made by mixing red and white and sometimes described as being a light red, but it is more accurately a bright undersaturated red. ...

Chlorides

Chlorides such as salt which is used for deicing roads is able to promote the corrosion of steel rebar. For this reason, in mixing concrete only fresh water may be used. A magnified crystal of a salt (halite/sodium chloride) In chemistry, a salt is any ionic compound composed of positively charged cations and negatively charged anions so that the product is neutral and without a net charge. ... This page is related to transport; you may be looking for the 2002 Bollywood movie Road. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ...

Concrete cancer

Also called concrete rot, is a rather ill defined term which means different things to different experts.[2]. It has nothing to do with the disease cancer in humans or animals, you will not catch cancer from living in a house with concrete cancer. When normal cells are damaged beyond repair, they are eliminated by apoptosis. ...

Alkali silica reaction

This is found when the cement is too alkaline, it is due to a reaction of the silica with the alkali. The silica (SiO₂) reacts with the alkali to form a silicate in the Alkali silica reaction (ASR), this causes localised swelling which causes cracking. The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... In chemistry, a silicate is a compound consisting of silicon and oxygen (SixOy), one or more metals, and possibly hydrogen. ...

See [3] and [4] for details

High alumina cement

This cement is banned in the UK in 1976 it was greatly used after world war two for making precast concrete objects.[5]. A ban is, generally, any decree that prohibits something. ... 1976 (MCMLXXVI) was a leap year starting on Thursday (the link is to a full 1976 calendar). ...

Sulphate attack

Sulfates can attack cement which can lead to an early failure.[6] Sulfate is the IUPAC name for the SO42- ion, consisting of a central sulfur atom single bonded to four tetrahedrally oriented oxygen atoms. ...

Fiber-reinforced concrete

Fiber-reinforcement is mainly used in shotcrete, but can also be used in normal concrete. Fiber-reinforced normal concrete are mostly used for on-ground floors and pavements, but can be considered for a wide range of construction parts (beams, pilars, foundations etc) either alone or with hand-tied rebars. Shotcrete and gunite are two commonly used terms for sprayed concrete. ...

Fiber (steel or "plastic" fibers) reinforced concrete is less expensive than hand-tied rebar, while still increasing the tensile strength many times. Shape, dimension and length of fibre is important. A thin and short fiber, for example short hair-shaped glass fiber, will only be effective the first hours after pouring the concrete (reduces cracking while the concrete is stiffening) but will not increase the concrete tensile strength. A normal size fibre for European shotcrete (1 mm diameter, 45 mm length—steel or "plastic") will increase the concrete tensile strength. The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... Fibre reinforced plastic (FRP) is a composite material comprising a polymer matrix reinforced with fibres usually of glass, carbon, or aramid (and in the case of Duroplast even cotton or wool) and is commonly used in aerospace, automotive and marine industries. ... Shotcrete and gunite are two commonly used terms for sprayed concrete. ...

Steel is the strongest commonly-available fiber, and come in different lengths (30 to 80 mm in Europe) and shapes (end-hooks). Steel fibres can only be used on surfaces that can tolerate or avoid corrosion and rust stains. In some cases, a steel-fiber surface is faced with other materials.

Glass fiber is inexpensive and corrosion-proof, but not as strong as steel. Recently, spun basalt fiber, long available in Eastern Europe, has become available in the U.S. and Western Europe. Basalt fibre is stronger and less expensive than glass, but historically, has not resisted the alkaline environment of portland cement well enough to be used as direct reinforcement. New materials use plastic binders to isolate the basalt fiber from the cement. Basalt fiber or fibre is a material made from extremely fine fibers of basalt, which is composed of the minerals plagioclase, pyroxene, and olivine. ... Current division of Europe into five (or more) regions: one definition of Eastern Europe is marked in orange Eastern Europe as a region has several alternative definitions, whereby it can denote: the region lying between the variously and vaguely defined areas of Central Europe and Russia. ... In chemistry, an alkali (from Arabic: al-qaly) is a specific type of base, formed as a carbonate, hydroxide or other ionic salt of an alkali metal or alkali earth metal element. ... Sampling fast set Portland cement Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and plaster. ...

The premium fibers are graphite reinforced plastic fibers, which are nearly as strong as steel, lighter-weight and corrosion-proof. Some experimeters have had promising early results with carbon nanotubes, but the material is still far too expensive for any building. Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ... Fibre reinforced plastic (FRP) is a composite material comprising a polymer matrix reinforced with fibres usually of glass, carbon, or aramid (and in the case of Duroplast even cotton or wool) and is commonly used in aerospace, automotive and marine industries. ... An electronic device known as a diode can be formed by joining two nanoscale carbon tubes with different electronic properties. ...

Non-steel reinforcement

Some construction cannot tolerate the use of steel. For example, MRI machines have huge magnets, and require nonmetallic buildings. Another example are toll-booths that read radio tags, and need reinforced concrete that is transparent to radio. The mri are a fictional alien species in the Faded Sun Trilogy of C.J. Cherryh. ...

In some instances, the lifetime of the concrete structure is more important than its strength. Since corrosion is the main cause of failure of reinforced concrete, a corrosion proof reinforcement can extend the life substantially.

For these purposes some structures have been constructed using fiber-reinforced plastic rebar, grids or fibers. The "plastic" reinforcement can be as strong as steel. Because it resists corrosion, it does not need a protective concrete cover of 30 to 50 mm or more as steel reinforcement does. This means that FRP-reinforced structures can be lighter, have longer lifetime and for some applications be price-competitive to steel-reinforced concrete. Fibre reinforced plastic (FRP) is a composite material comprising a polymer matrix reinforced with fibres usually of glass, carbon, or aramid (and in the case of Duroplast even cotton or wool) and is commonly used in aerospace, automotive and marine industries. ... Fibre reinforced plastic (FRP) is a composite material comprising a polymer matrix reinforced with fibres usually of glass, carbon, or aramid (and in the case of Duroplast even cotton or wool) and is commonly used in aerospace, automotive and marine industries. ...

The main barrier to use of FRP reinforcement is the fact that it is neither ductile nor fire resistant. Structures employing FRP rebars may therefore exhibit a less ductile structural response, and decreased fire resistance.

See also

• Building construction
• Construction engineering
• Structural engineering
• Tie rod