Composite Rebars Selection Guide for Construction
Composite rebars are a substitute for the conventional steel rebars, which are used to provide a non-corrosive reinforcement to concrete and add service life to it. They can be up to 75% lighter than the traditional steel rebars, which makes it easy to carry and transport. They are light-weight, rust and corrosion-proof, and flexible, which allows for a higher degree of freedom in building designs. Composite bars are used in weight-sensitive applications, and environmentally sensitive areas where moving heavy equipment is undesirable. They are gaining acceptance in a number of major applications, including industrial engineering, highway construction, railway construction, residential construction, etc.
Concrete has long been used as a building material for its high compressive strength, good durability and low cost. However, its well-known Achilles’ heel is its brittleness and limited tensile strength. This was solved quite handily about a century ago by using reinforcing bars (rebar) of steel in the tension side of concrete structures. Steel rebar is functionally efficient and relatively inexpensive, so it does a good job in most cases. However, steel rebar has its own weakness: susceptibility to corrosion (oxidation) when exposed to salts, aggressive chemicals and moisture. As it corrodes, steel rebar swells and increases the tensile load on the concrete, which begins to crack and spall, creating openings that lead to further and faster deterioration of the steel and concrete. This necessitates costly repair and maintenance and, if allowed to progress far enough, it can compromise the structure’s integrity. Numerous coatings and penetrants have been introduced over the decades to help seal out moisture from concrete, and rebar itself has been upgraded with epoxy coatings or the use of stainless steel. But it isn’t always possible to prevent corrosion in the long term. Further, steel rebar’s penchant to conduct electrical and magnetic fields makes it undesirable in concrete specified for certain power-generation, medical/scientific-imaging, nuclear and electrical/electronic applications.
The rising prices of steel have led to the inflation in prices of steel rebars and led many contractors and builders to look for alternatives to the traditional steel bars. As composite rebars are unaffected by the climbing steel prices and the prices of composite rebars are fairly stable, builders have started to adopt composite bars in various construction projects. The rising uses of composite rebars in construction foundations of various residential construction and civil engineering projects are likely to augment the demand for composite bars. Moreover, the growing uses of composite rebars in industrial engineering to reinforce concrete tanks, concrete floors, sewage well's covers, etc. are anticipated to generate substantial demand for composite rebars in the forecast period. Advancements in material science and the trend of smarter building designs have pushed the use of composite rebars to the forefront. However, the initial high cost of composite rebars may dissuade consumers from employing them in construction projects and hinder the growth of the composite rebars market to some extent.
Nearing commercialization is HollowRebar, invented by engineering professors at Oregon State University (Corvallis, Ore.) and currently owned by Composite Rebar Technologies Inc. (CRT, Madison, Wis.). The product features a pultruded inner layer of vinyl ester resin with continuous glass fiber reinforcement and a hollow center. This hollow, continuously reinforced rod is covered with a discontinuously reinforced sleeve that is bonded to the bar as part of the continuous production process.
Newer generation composite rebar can add a price advantage to its other benefits, then it will stand a much better chance of being specified in higher volume. That’s both a challenge and an opportunity for the whole composites industry to embrace.
The rising prices of steel have led to the inflation in prices of steel rebars and led many contractors and builders to look for alternatives to the traditional steel bars. As composite rebars are unaffected by the climbing steel prices and the prices of composite rebars are fairly stable, builders have started to adopt composite bars in various construction projects. The rising uses of composite rebars in construction foundations of various residential construction and civil engineering projects are likely to augment the demand for composite bars. Moreover, the growing uses of composite rebars in industrial engineering to reinforce concrete tanks, concrete floors, sewage well's covers, etc. are anticipated to generate substantial demand for composite rebars in the forecast period. Advancements in material science and the trend of smarter building designs have pushed the use of composite rebars to the forefront. However, the initial high cost of composite rebars may dissuade consumers from employing them in construction projects and hinder the growth of the composite rebars market to some extent.
Nearing commercialization is HollowRebar, invented by engineering professors at Oregon State University (Corvallis, Ore.) and currently owned by Composite Rebar Technologies Inc. (CRT, Madison, Wis.). The product features a pultruded inner layer of vinyl ester resin with continuous glass fiber reinforcement and a hollow center. This hollow, continuously reinforced rod is covered with a discontinuously reinforced sleeve that is bonded to the bar as part of the continuous production process.
Newer generation composite rebar can add a price advantage to its other benefits, then it will stand a much better chance of being specified in higher volume. That’s both a challenge and an opportunity for the whole composites industry to embrace.
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