Editing Reinforced concrete (section)

==Fiber-reinforced concrete==
{{Main|Fiber-reinforced concrete}}
Fiber reinforcement is mainly used in [[shotcrete]], but can also be used in normal concrete. Fiber-reinforced normal concrete is mostly used for on-ground floors and pavements, but can also be considered for a wide range of construction parts (beams, pillars, foundations, etc.), either alone or with hand-tied rebars.

Concrete reinforced with fibers (which are usually steel, [[glass]], [[Fiber-reinforced plastic|plastic fibers]]) or cellulose polymer fiber is less expensive than hand-tied rebar.{{Citation needed|date=December 2017}} The shape, dimension, and length of the fiber are important. A thin and short fiber, for example short, hair-shaped glass fiber, is only effective during the first hours after pouring the concrete (its function is to reduce cracking while the concrete is stiffening), but it will not increase the concrete tensile strength. A normal-size fiber for European shotcrete (1&nbsp;mm diameter, 45&nbsp;mm length—steel or plastic) will increase the concrete's tensile strength.  Fiber reinforcement is most often used to supplement or partially replace primary rebar, and in some cases it can be designed to fully replace rebar.<ref>Fiber Concrete in Construction, Wietek  B., Springer 2021, pages 268; ISBN 978-3-658-34480-1</ref>

Steel is the strongest commonly available fiber,{{Citation needed|reason=I thought Aramid fibers were stronger, need a reliable source for this statement as it may not be fact based or is out-of-date.|date=December 2017}} and comes in different lengths (30 to 80&nbsp;mm in Europe) and shapes (end-hooks). Steel fibers 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 ductile as steel. Recently, spun [[basalt fiber]], long available in [[Eastern Europe]], has become available in the U.S. and Western Europe. Basalt fiber 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.

The premium fibers are [[graphite]]-reinforced plastic fibers, which are nearly as strong as steel, lighter in weight, and corrosion-proof.{{Citation needed|date=December 2017}} Some experiments have had promising early results with [[carbon nanotubes]], but the material is still far too expensive for any building.{{Citation needed|reason=this statement needs substantiation|date=December 2017}}