Location Of Rebar in Concrete

Location of Rebar in a Reinforced Concrete Structure Is Very Important While Carrying out Modifications

by CSI Concrete Scanning

Concrete has a very high compressive strength compared to its tensile strength which is very low. It is possible to increase this tensile strength by introducing rebar into concrete to make a reinforced concrete structure which can then take both compressive and tensile stresses and make for structures that have strength and durability.

Concrete lends itself very easily to be molded into any shape that is desired, because when it is first manufactured it is in a plastic state, which over a short period of time hardens, while continually developing strength. Rebar in reinforced concrete needs to be put at very specific locations so that it allows the structure to have the required tensile strength. This is done by using spacers and other devices to lock rebar into the specific required locations, which remain so, even when the fluid concrete is poured into the formwork that makes up the shape of the desired structure. It can be in columns, walls, beams, slabs or any shape desired. Building codes determine the distance this rebar needs to be from the surface of the concrete. Rebar is made of steel which is vulnerable to rust from atmospheric conditions. This is why rebar needs to be kept at a certain distance within the concrete to prevent any rust formation. Rust formation can cause rebar to lose its form and strength and thus affect the strength of the reinforced concrete structure.

Quite often it is necessary to create new ducts or holes in a reinforced concrete structure to position services or other utilities. When this requires the concrete structure to be drilled through or partially, it is very important to make sure that any such modification is not hampered by the presence of the rebar. It then becomes very important to know the exact position of the rebar, so that any drilling or breaking done does not come across a rebar. While this can negate the entire process of installing new utilities, because of this obstruction, any damage to the rebar can severely affect the strength of the structure.

Fortunately, technologies are available that allow the location of the rebar in concrete to be pinpointed, without any necessity for damaging the concrete to locate the rebar. These concrete scanning operations use ground penetrating radar in locating rebar in concrete slabs. This allows the exact location for the rebar to be established so that any subsequent operations can avoid damaging them. There are times when a structure is showing signs of distress, and at such times one of the first things that engineers do is check on the position of the rebar, as any shift from previously designed parameters can lead to weaker structures. Location of rebar in concrete can help engineers to assess the soundness of a structure.

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