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Encyclopedia > Rebar
A tied rebar beam cage. This will be embedded inside of cast concrete to lend it strength. A bit of rust on the rebar actually increases the surface area and bonds well with concrete. The high pH level of the concrete will minimise further rust damage to the rebar. In cases where too much concrete poison is dissolving the cement stone of the concrete, the rebar is then also no longer protected and rust can be seen to creep through cracks in faulty concrete. This becomes particularly apparent in bridge structures, such as the Gardiner Expressway, and parking garages. Common countermeasures include epoxy coating of the rebar, keeping a slight electrical current running through the rebar and the choice of cement types that have greater sulphate resistance.

Rebar, a portmanteau for reinforcing bar or reinforcement bar, is common steel bar, an important component of reinforced concrete and reinforced masonry structures. It is usually formed from carbon steel, and is given ridges for better frictional adhesion to the concrete. It can also be described as reinforcement or reinforcing steel. In Australia it is colloquially known as reo. 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. ... Concrete being poured, raked and vibrated into place in residential construction in Toronto, Ontario, Canada. ... The correct title of this article is . ... View of the Gardiner Expressway, west of downtown Toronto, from the pedestrian overpass at the foot of Roncesvalles Avenue. ... 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... Sulfate is the IUPAC name for the SO42- ion, consisting of a central sulfur atom single bonded to four tetrahedrally oriented oxygen atoms. ... A portmanteau (IPA pronunciation: ) is a word or morpheme which fuses two or more words or parts of words to give a combined or loaded meaning. ... The steel cable of a colliery winding tower. ... Reinforced concrete at Sainte Jeanne dArc 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 a material that would otherwise be brittle. ... Masonry in action; a Mason at work. ... Carbon steel, also called plain carbon steel, is a metal alloy, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. ... friction is the force that opposes the relative motion or tendency toward such motion of two surfaces in contact. ... Look up Colloquialism in Wiktionary, the free dictionary. ...

Contents

Use in concrete and masonry

Concrete is a material that is very strong in compression, but virtually without strength in tension. To compensate for this imbalance in concrete's behavior, rebar is cast into it to carry the tensile loads. Concrete being poured, raked and vibrated into place in residential construction in Toronto, Ontario, Canada. ... Look up material in Wiktionary, the free dictionary. ... Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume. ... Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ... Load may mean: Look up Load in Wiktionary, the free dictionary. ...


Masonry structures and the mortar holding them together have similar properties to concrete and also have a limited ability to carry tensile loads. Some standard masonry units like blocks and bricks are made with strategically placed voids to accommodate rebar, which is then secured in place with grout. This combination is known as reinforced masonry. Masonry in action; a Mason at work. ... Mortar holding weathered bricks. ... An old brick wall in English bond laid with alternating courses of headers and A brick is a block of ceramic material used in masonry construction and sized to be layed with one hand using mortar. ... Grout is a construction material used to embed rebars in masonry walls, connect sections of pre-cast concrete, fill voids, and seal joints (like those between tiles). ...


While any material with sufficient tensile strength could conceivably be used to reinforce concrete, steel and concrete have similar coefficients of thermal expansion: a concrete structural member reinforced with steel will experience minimal stress as a result of differential expansions of the two interconnected materials caused by temperature changes. During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. ... Stress is the internal distribution of force per unit area that balances and reacts to external loads applied to a body. ...


Physical characteristics

Steel has an expansion coefficient nearly equal to that of modern concrete. If this weren't so, it would be useless for reinforcing concrete.[1] Although rebar has ridges that bind it mechanically to the concrete with friction, it can still be pulled out of the concrete under high stresses, an occurrence that often precedes a larger-scale collapse of the structure. To prevent such a failure, rebar is either deeply embedded into adjacent structural members, or bent and hooked at the ends to lock it around the concrete and other rebar. This first approach increases the friction locking the bar into place while the second makes use of the high compressive strength of concrete. Mechanics (Greek ) is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. ... Stress is the internal distribution of force per unit area that balances and reacts to external loads applied to a body. ... Collapse is a puzzle game published in 1999 by the software company GameHouse. ... This article does not cite any references or sources. ...


Common rebar is made of unfinished steel, making it susceptible to rusting. As rust takes up greater volume than the iron or steel from which it was formed, it causes severe internal pressure on the surrounding concrete, leading to cracking, spalling, and ultimately, structural failure. This is a particular problem where the concrete is exposed to salt water, as in bridges built in areas where salt is applied to roadways in winter, or in marine applications. Epoxy-coated rebar or stainless steel rebar may be employed in these situations at greater initial expense, but significantly lower expense over the service life of the project. Fiber-reinforced polymer rebar is now also being used in high-corrosion environments. A blacksmith removing rust with sand prior to welding Rust damage in automobiles can create hidden dangers. ... Spall are flakes of a material that are broken off a larger solid body. ... Structural failure refers to loss of the load-carrying capacity of a component or member within a structure or of the structure itself. ... 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... The 630 foot high, stainless-clad (type 304L) Gateway Arch defines St. ... Fibre-reinforced plastic (FRP) (also Fibre-reinforced polymer) 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. ...

Welding

Most grades of steel used in rebar are suitable for welding, which can be used to bind several pieces of rebar together. However, welding can reduce the fatigue life of the rebar, and as a result rebar cages are normally tied together with wire. Welding is a joining process that produces coalescence of materials (typically metals or thermoplastics) by heating them to welding temperature, with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material. ... In materials science, fatigue is the progressive, localised, and permanent structural damage that occurs when a material is subjected to cyclic or fluctuating strains at nominal stresses that have maximum values less than (often much less than) the static yield strength of the material. ...


Safety

To prevent workers and / or pedestrians from accidentally impaling themselves, the protruding ends of steel rebar are often bent over or covered with special steel-reinforced plastic "plate" caps. "Mushroom" caps may provide protection from scratches and other minor injuries, but provide little to no protection from impalement.


Rebar sizes and grades

US Imperial sizes

Imperial bar designations represent the bar diameter in fractions of ⅛ inch, such that #8 = 88 inch = 1 inch diameter. This convention applies to #8 and smaller bars only.

Imperial

Bar Size

"Soft"

Metric Size

Weight

(lbft)

Weight

(kg/m)

Nominal Diameter

(in)

Nominal Diameter

(mm)

Nominal Area

(in²)

Nominal Area

(mm²)

#3 #10 0.376 0.561 0.375 9.525 0.11 71
#4 #13 0.668 0.996 0.500 12.7 0.20 129
#5 #16 1.043 1.556 0.625 15.875 0.31 200
#6 #19 1.502 2.24 0.750 19.05 0.44 284
#7 #22 2.044 3.049 0.875 22.225 0.60 387
#8 #25 2.670 3.982 1.000 25.4 0.79 509
#9 #29 3.400 5.071 1.128 28.65 1.00 645
#10 #32 4.303 6.418 1.270 32.26 1.27 819
#11 #36 5.313 7.924 1.410 35.81 1.56 1006
#14 #43 7.650 11.41 1.693 43 2.25 1452
#18 #57 13.60 20.284 2.257 57.33 4.00 2581

Canadian Metric sizes

Metric bar designations represent the nominal bar diameter in millimeters, rounded to the nearest 5 mm.

Metric

Bar Size

Mass

(kg/m)

Nominal Diameter

(mm)

Cross-Sectional

Area (mm2)

#10 M 0.785 11.3 100
#15 M 1.570 16.0 200
#20 M 2.355 19.5 300
#25 M 3.925 25.2 500
#30 M 5.495 29.9 700
#35 M 7.850 35.7 1000
#45 M 11.775 43.7 1500
#55 M 19.625 56.4 2500

European Metric sizes

Metric bar designations represent the nominal bar diameter in millimetres. Bars in Europe will be specified to comply with the standard EN 10080 (awaiting introduction as of early 2007), although various national standards still remain in force (e.g. BS 4449 in the United Kingdom).

Metric

Bar Size

Mass

(kg/m)

Nominal Diameter

(mm)

Cross-Sectional

Area (mm2)

6,0 0.222 6 28.3
8,0 0.395 8 50.3
10,0 0.617 10 78.5
12,0 0.888 12 113
14,0 1.21 14 154
16,0 1.58 16 201
20,0 2.47 20 314
25,0 3.85 25 491
28,0 4.83 28 616
32,0 6.31 32 804
40,0 9.86 40 1257
50,0 15.4 50 1963

Grades

Historically in Europe, rebar comprised mild steel material with a yield strength of approximately 250 N/mm². Modern rebar comprises high-yield steel, with a yield strength more typically 500 N/mm². Rebar can be supplied with various grades of ductility, with the more ductile steel capable of absorbing considerably greater energy when deformed - this can be of use in design against earthquakes for example. Ductility is the physical property of being capable of sustaining large plastic deformations without fracture (in metals, such as being drawn into a wire). ... An earthquake is the result from the sudden release of stored energy in the Earths crust that creates seismic waves. ...


Rebar Designation

For clarity, reinforcement is usually tabulated in a Reinforcement Schedule on construction drawings. This eliminates ambiguity in the various notations used in different parts of the world. The following list provides examples of the different notations used in the architecutral, engineering, and construction industry.


United States

Designation Explanation
#4 @ 12 oc, T&B, EW Number 4 rebars spaced 12 inches on centre (centre-to-centre distance) on both the top and bottom faces and in each way as well, i.e. longitudinal and transverse
3 #4 Three number 4 rebars
#3 ties @ 9 oc, 2 per set Number 3 rebars used as stirrups, spaced at 9 inches on centre. Each set consists of two ties, which is usually illustrated.

h. ...

See also

// Fusion bonded epoxy coating, also known as fusion-bond epoxy powder coating and commonly referred to as FBE coating, is an epoxy based powder coating that is widely used to protect various sizes of steel pipes used in pipeline construction, concrete reinforcing rebars and on a wide variety of piping... Fluted wood dowel Dowel joint A dowel is a pin, usually made of wood, plastic or metal, used to secure two objects together. ... Concrete cover is the region between the exposed concrete surface and the nearest surface of the reinforcing bar, in reinforced concrete members. ... Reinforced concrete at Sainte Jeanne dArc 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 a material that would otherwise be brittle. ... A steel fixer is a tradesman who positions and secures steel reinforcing bars, also known as rebar and steel mesh used in reinforced concrete on construction projects. ... Panelized ceiling slab forming system with temporary support structures on a university dorm project. ...

External links

Wikimedia Commons has media related to:
Reinforcement
  • Stainless rebar information
  • OSHA Rebar Impalement Protection Measures

  Results from FactBites:
 
Rebar - Wikipedia, the free encyclopedia (526 words)
Rebar is common steel reinforcing bar, an important component of reinforced concrete and reinforced masonry structures.
Although rebar has ridges that bind it mechanically to the concrete with friction, it can still be pulled out of the concrete under high stresses, an occurrence that often precedes a larger-scale collapse of the structure.
Epoxy-coated rebar or stainless steel rebar may be employed in these situations at greater initial expense, but significantly lower expense over the service life of the project.
about (338 words)
Rebar was founded by Matthew Passmore, John Bela, Jed Olson and Judson Holt, all of whom built the library.
Rebar’s work is fundamentally motivated by the desire to animate the arbitrariness of what French sociologist Pierre Bourdieu calls the doxa: the uncontested acceptance of the daily life-world and the adherence to a set of social relations we take to be self evident.
Rebar’s projects are intended to engage social, ecological and cultural processes as they unfold materially in space and time.
  More results at FactBites »

 
 

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