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Steel reinforcement as the name suggests is a term that explains the use of steel to strengthen and reinforce concrete structures. This reinforcement is done using different steel products.
What is steel reinforcement?
Steel bars and wires that are used to strengthen and support concrete in buildings are called steel reinforcement. Steel bars and wires are put inside concrete structures to add to the load bearing capacity of the structure.
To understand steel reinforcement, you need to also learn about concrete reinforcement. This term explains the concrete structures erected with the help of steel reinforcement. Simply put, a concrete structure with steel reinforcement (steel bars and wires) is called reinforced concrete and the process is called concrete reinforcement.
Steel reinforcement example
To understand steel reinforcement better consider this example. Imagine construction of a large pillar like the ones in temples and churches. These large structures are built with reinforced concrete.
The masons begin by constructing cross sections using steel bars; square, rectangular or circular, according to the shape of the pillar. For a rectangular pillar, four long vertical bars are taken and fixed into the foundation in a square shape.
Next step will be bending steel bars into rectangular cross sections. These cross sections are connected to the vertical bars in such a way that the former encloses the vertical bars from outside. The first rung is placed at the very base of the vertical bars.
These cross sections are then stacked one on top of the other leaving a roughly a 15 cm distance between each. Concrete is filled inside this structure and a coat of concrete is also applied on the outside of the pillar.
The science behind steel reinforcementPlain concrete does poorly when it comes to tensile strength but has excellent compressive strength. Combining this building raw material with the tensile strength of steel bars and wires means that reinforced concrete and steel work together to contribute to the load bearing capacity of the building.
Types of steel reinforcement
There are two main types of steel products used for steel reinforcement:
- Steel wires
Rebars or reinforcing bars are steel bars specifically built for the construction industry for concrete support. The surface of a rebar is often deformed to increase the bonding with concrete.
There are different types of rebar:
- Carbon steel bars
Carbon steel is used for purposes where ultimate tensile strength is taken into consideration. However, ductility and corrosion resistance are very low.
- Mild steel bars
Mild steel bars have round sections whose diameter varies from 6 mm to 50 mm. They are characterised by the plain surface of the bar. These rebars are easy to cut and bend. The grade of this rebar is determined by the yield stress, which is denoted on the bar, i.e; “FE250” where FE stands for iron and 250 means yield stress.
- High Yield Strength Deformed (HYSD) bars
Deformed bars are distinguished by a ribbed rough surface on the bar. This is done to increase the bar bonding between reinforcement and concrete and to maintain friction between them.
HYSD bars are divided into:
Known to be the best among steel bars, TMT bars showcase features including qualities like excellent ductility, high corrosion resistance, yield strength, ultimate tensile strength, better elongation and better weldability.
Cold Twisted Bars – CTD
Cold Twisted Bars are also called TOR steel in India. Once hot steel is obtained from the furnace it is cooled at ambient temperature and then stretched and twisted to increase yield strength.
- Epoxy coated rebar
Epoxy powder is applied on hot steel at a pre-set temperature using an electrostatic spray to obtain epoxy coated rebar. These are extremely corrosion resistant and are largely used in infrastructures, buildings, bridges, roadways, etc.
- Galvanised rebar
When a rebar is coated with Zinc it is then known as galvanised rebars. Featuring excellent corrosion resistance, they perform better than epoxy coated rebars.
- Stainless steel rebar
Designed similar to carbon steel, stainless steel rebars have a long lifespan. These are highly corrosion resistant, and less maintenance is required compared to other kinds of steel.
Grades of steel reinforcement
According to IS 1786:2008 the grades of high strength deformed bars and wires for concrete reinforcement used in construction is as follows:
- Fe 415, Fe 415D, Fe 415S
- Fe 500, Fe 500D, Fe 500S
- Fe 550, Fe 550D
- Fe 600
Specifications of steel reinforcement as per IS Code
There are specifications for steel reinforcement that can be used in a building. For example, have a look at the chemical composition of reinforcement steel:
|Grades of steel rebars and percentage of chemical composition
|Sulphur and phosphorus
Similarly, according to the IS Code, the nominal sizes of bars/wires is as follows: 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 28 mm, 32 mm, 36 mm, 40 mm, 45 mm and 50 mm
If you are looking for deformed steel bars and wires for steel reinforcement visit Tata nexarc’s Procurement platform. We have partnerships with numerous steel suppliers who can match your steel requirements at reasonable prices.