Is too much concrete cover bad?

Large cover leads to increased crack widths. Large crack widths (greater than 0.3 mm) causes the ingress of moisture and chemical attack to the concrete. This leads to corrosion of reinforcement and affects the durability of concrete. Therefore an upper limit should be imposed on the cover (usually 75 mm).

What are the advantages and disadvantages of providing large clear cover to reinforcement in flexural members?

What are the disadvantages in providing large cover for Concrete Cover for Reinforcement? Large cover depths (50–75 mm) are required to protect reinforcement against corrosion in aggressive environments, but thick cover leads to increased crack widths in reinforced concrete flexural members.

What happens when there is not enough cover in a concrete member?

In the same way, just imagine what would happen if a building accidentally catches fire (let us say cover is not provided). There will be no resistance. The steel will be directly subjected to extreme heat which will melt the steel present in the structural members thereby leading to collapse of the building.

What is clear cover in reinforcement?

The clear cover is the distance between the exposed concrete surface (without plaster and other finishes) to the nearest surface of the reinforcing bar Look into the following image for more detail.

What happens if concrete cover is more?

Consequently, with an increase in concrete cover the crack width will increase. (ii) The weight of the concrete structure is increased by an increase in concrete cover. This effect is a critical factor in the design of floating ships and platforms where self-weight is an important design criterion.

Why cover is provided in reinforcement?

Concrete cover is crucial in order to protect the reinforcing steel from corrosion caused by environmental effects. When steel reinforcement corrodes, it will rust and expand to a greater volume than the steel itself. This action results in the cracking, spalling and delamination of the concrete covering the steel.

Why is clear cover important in RCC structure?

Clear cover is provided in RCC structure to protect the reinforcement from corrosion, it is moisture Control Programme. It provide fire resistance and insulation to steel which is embedded in concrete. It protect the reinforcement from chemical attack and moisture, that’s leads to deterioration of reinforcement.

Why do people give clear covers?

1. To protect the reinforcement from corrosion. 2. To provide fire resistance to the reinforcement.

Why clear cover is provided?

Clear cover is provided in RCC structure to protect the reinforcement from corrosion, it is moisture Control Programme. It provide fire resistance and insulation to steel which is embedded in concrete. Reinforcement is sufficiently embedding to enable to be stressed without slipping.

What is reinforcement cover?

Concrete cover, in reinforced concrete, is the least distance between the surface of embedded reinforcement and the outer surface of the concrete (ACI 130). The concrete cover depth can be measured with a cover meter.

What is clear cover in concrete?

Clear cover is the distance measured from the exposed concrete surface (Without plaster and other finishes) to the nearest surface of the reinforcing bar.

What are the requirements for clear concrete cover for reinforcement?

Unless indicated otherwise on the drawings, clear concrete cover for reinforcement (exclusive of plaster or other decorative finish shall be as follows) :a) At each end of reinforcing bar not less than 25 mm, nor less than twice the diameter of such bar.

What tolerances must reinforcement be placed within?

Unless otherwise specified by the Engineer-in-charge, reinforcement shall be placed within the following tolerances: The cover shall in no case be reduced by more than one third of specified cover or 5mm whichever is less.

What are the specifications for reinforcement cover for different structural members?

Below are the specifications for reinforcement cover for different structural members in different conditions. a) At each end of reinforcing bar, concrete cover not less that 25 mm or less than twice the diameter of the bar should be provided.

What is the nominal cover of a reinforcement bar?

However, for a longitudinal reinforcing bar in a column, nominal cover shall in any case not be less than 40 mm, or less than the diameter of such bar. In the case of columns of minimum dimension of 200 mm or under, whose reinforcing bars do not exceed 12 mm, a nominal cover of 25 mm.