Types of Rebar Support in RCC Member

RCC member is composed of reinforcement and concrete. Typically we use deformed steel bar as reinforcement. But the question is - what is Rebar support and why do reinforcements need them.

Reinforcement support, rebar support
Block

What is the "rebar support?

To prevent displacement of reinforcement during working and concreting we provide supports to them in RCC members. These are called rebar support. Not clear? Keep reading...


Why does reinforcement need supports?

In reinforced cement concrete (RCC) member, we provide concrete cover for all reinforcements. Because if the reinforcement exposes to weather it gets corrosion. And you know what the corrosion means for reinforcement.

Reinforcements need different thickness of concrete cover in different situation. Read this article "minimum concrete clear cover for reinforcement".

There is a possibility to displace the unsupported reinforcements during working and pouring concrete. To prevent the reinforcement from displacement, we need to give them support.

So far, we get the concept about rebar support. Now we'll see what kind of supports are used for steel bar in RCC member.

Typically used reinforcement supports in RCC member

We generally use the following types of rebar support -
  • Mortar Block
  • Steel chair
Mortar Block: This is the most common type of bar support. 1:3 cement-sand mortar is commonly used for making mortar block. The thickness of this block depends on the clear cover for steel bar. This type of bar support is generally used in edges of RCC member.

Rebar support, Support for reinforcement
Chair as "Rebar Support"
Chair: To separate top and bottom reinforcement in double reinforced RCC member this type of bar support is commonly used. Normally 10mm diameter steel bars are used for this purpose. Calculating the height of the chair is a bit tricky. I'll write about this later in a separate article. So subscribe by RSS or Email to get update when it is published.

Besides these common types of support, there is a plastic bar support which is used in the RCC member built on ground. This is nicely explained in "CRSI - Manual of Standard Practice" which is also refered by "ACI-315-99".

There are many sized and shaped of rebar supports available in the market ready for use. But in small RCC members like beam and slab of a building, you don't need to buy those expensive rebar supports.

Share your experience
Which types of rebar support have you used so far?

 

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