Definition, Purpose, and History of Rebar – Rebar is short for reinforcing bar, used to strengthen and support concrete and masonry structures. – It is made of steel and increases the tensile strength of the structure. – Rebar has a ribbed surface to enhance bonding with concrete and prevent slippage. – Carbon steel is the most common type of rebar, but other options like stainless steel and composite bars are available. – Coatings like zinc or epoxy resin can be applied to protect against corrosion. – Rebar has been used since ancient times, with iron or wooden rods in arch construction. – In the 19th century, steel bars were embedded in concrete, leading to the development of modern reinforced concrete. – Notable figures in the invention and popularization of reinforced concrete include Joseph Monier and Ernest L. Ransome. – Twisted iron rebar was initially met with skepticism but was used in the first reinforced concrete bridge in the United States. – Different reinforcing systems, such as the mushroom system and diamond-shaped rebar, were experimented with but faced criticism and were eventually replaced. Use and Benefits of Rebar – Rebar is used in concrete to provide tensile strength, compensating for its weakness in tension. – Primary reinforcement ensures the overall resistance needed to support design loads. – Secondary reinforcement, also known as distribution or thermal reinforcement, limits cracking and resists stresses caused by temperature changes and shrinkage. – Rebar can also be embedded in masonry walls for added strength and stability. – Rebar significantly increases the tensile strength of concrete structures, making them more durable and resistant to cracking. – It enhances the structural integrity and stability of buildings, bridges, and other reinforced concrete elements. – The use of rebar allows for the construction of larger and more complex structures. – Different types of rebar, such as stainless steel or composite bars, offer specific performance advantages in certain construction projects. – Coatings like zinc or epoxy resin protect rebar from corrosion, extending its lifespan in harsh environments. Standards and Specifications for Rebar – Deformations on steel bar reinforcement were standardized in the US construction industry around 1950. – ASTM A305-49 established the requirements for deformations, including rib height and spacing. – Current specifications for steel bar reinforcing, such as ASTM A615 and ASTM A706, maintain the same deformation requirements as ASTM A305-49. – These standards ensure the quality and performance of rebar in reinforced concrete structures. – Compliance with these specifications is essential for the safety and longevity of the construction projects. Physical Characteristics, Corrosion Prevention, and Sizes of Rebar – Steel has a thermal expansion coefficient similar to modern concrete. – Rebar can be pulled out of concrete under high stresses, leading to collapse. – Rebar is deeply embedded or bent and hooked to prevent failure. – Unfinished tempered steel rebar is susceptible to rusting. – Concrete cover must provide a pH value higher than 12 to avoid corrosion. – Uncoated steel rebars can be prone to rusting. – Corrosion-resistant materials like epoxy-coated, galvanized, or stainless steel rebars are used in saltwater or marine applications. – Epoxy-coated rebar provides better corrosion resistance than uncoated rebar. – Damage to epoxy-coated rebar reduces its long-term corrosion resistance. – Stainless steel rebar with low magnetic permeability is used to avoid magnetic interference. – US/Imperial bar sizes are given in units of 1/8 inch. – The cross-sectional area of a bar is calculated using the formula (bar size/9)^2. – Bar sizes larger than #8 follow the 1/8-inch rule and skip certain sizes due to historical convention. – Sizes smaller than #3 are not recognized as standard sizes. – US/Imperial bar sizes can be converted to metric sizes, but it may result in physically different sized bars. – Fiber-reinforced plastic (FRP) rebar is used in high-corrosion environments. – FRP rebar is available in various forms like spirals, rods, and meshes. – Most commercially available FRP rebar is made from unidirectional fibers set in a thermoset polymer resin. – Glass fiber types of FRP rebar have low electrical conductivity and are non-magnetic. Rebar Sizes in Different Countries – Metric bar designations represent the nominal bar diameter in millimeters. – Preferred bar sizes in Europe comply with Table 6 of the standard EN 10080. – Various national standards still remain in force, such as BS 4449 in the United Kingdom. – Reinforcement for concrete construction in Australia follows the requirements of Australian Standards AS3600 and AS/NZS4671. – Reinforcement for concrete construction in New Zealand complies with the requirements of AS/NZS4671. – Rebars in India are available in different grades such as FE 415, FE 415D, FE 415S, FE 500, FE 500D, FE 500S, FE 550, FE 550D, and FE 600. – Very large format rebar sizes are available from specialty manufacturers. – Jumbo bars are commonly used as anchor rods for large structures in the tower and sign industries. – Fully threaded rebar with coarse threads is produced to satisfy rebar deformation standards and allow for custom nuts and couplers.https://en.wikipedia.org/wiki/Rebar