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What are the potential problems of excessive concrete covers?

In reinforced concrete structures cover is normally provided to protect steel reinforcement from corrosion and to provide fire resistance. However, the use of cover more than required is undesirable in the following ways:

(i) The size of crack is controlled by the distance of longitudinal bars to the point of section under consideration. The closer a bar is to this point, the smaller is the crack width. Therefore, closely spaced bars with smaller cover will give narrower cracks than widely spaced bars with larger cover. 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.

(iii) For the same depth of concrete section, the increase of concrete cover results in the reduction of the lever arm of internal resisting force.


This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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5 comments on "What are the potential problems of excessive concrete covers?"

Armand says:

For parking structure, if we post-tension the slab in th eparking structure, can we obtain epoxy-coated stran? What are the problems with this material

Ashadu98 says:

What should be the maximum concert cover to prevent concert from cracking due this maximum cover .

Steven says:

50 mm

Vinod kumar says:

What will happen if cover of main reinforcement bars of vertical bars iin Dmc piles ncrrased .if bottom cover is provided 30 cm from bottom of piles..?

Abhishek Singh says:

Is 5 mm more cover create a big problem on our structure like we provided 35 mm cover instead of 30 mm cover as per our design and drawing.

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