Cover Block :-
A cover block is used to provide space between re-bar and ground( outer surface) so that concrete may flow underneath the rebar. Rebars are fully encases in concrete to prevent corrosion.
A cover block is used to provide space between re-bar and ground( outer surface) so that concrete may flow underneath the rebar. Rebars are fully encases in concrete to prevent corrosion.
Sometimes binding wire is embeded in cover block to provide better holding and stability.
Types of cover block
1-Cement masonry cover block
2-Wooden cover block.
3-Polyvinyl chloride (PVC) cover block
4- Steel cover block
5-Stone cover block
6-Aluminum cover block
SECTION 'A'
Reinforcement shall have concrete
cover (nominal) and the thickness of such cover (exclusive of plaster or other decorative finish)
shall be as follows:
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1- At each end of reinforcing bar not less than 25 mm, or twice the diameter of such bar whichever is greater;
2-.For a longitudinal reinforcing bar in a
column not less than 40 mm or the diameter of such bar whichever is greater.
In the case of columns with a minimum dimension of 200 mm or tinder, whose reinforcing bars do not exceed 12 mm, the cover may be recluced to 25 mm;
3- For longitudinal reinforcing bar in a beam not less than 25 mm or the diameter of such bar, whlchever is greater;
4- For tensile, compressive, shear or other
rieinforcement in a slab not less than I5 mm or the diameter of such reinforcement,
whichever is greater; and
For any other reinforcement not less than
15 mm or the diameter of such reinforcement, whichever is greater.
NOTE - The values of cover suggested are nominal cover as specified in the drawings.
Section-B
increased cover thickness may be provided when the surfaces of concrete members
are exposed to the action of harmful chemicals (as in the case of concrete in contact with earth contaminated with such chemicals), acid, vapour, saline atmosphere, sulphurous smoke (as in the case of steam-operated railways), etc, and such increase of cover may be between I5 and 50 mm over the values given in Section 'A' above as may be specified by the Engineer-in-Charge. However, in no case cover should exceed 75 mm.
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# For reinorced concrete members of
marine structures totally immersed in sea water,
the cover shall be 40 mm more than that specified in section' A', but total cover should not exceed 75 mm.
#For reinforced concrete structures/ structural members, periodically immersed in sea water or subject to sea spray, the cover of concrete shall be 50 mm more than that specified in Section 'A', but total cover should not exceed 75 mm.
Generally 4-5 cover blocks are required per square metre of slab.
For concrete of grade M25 and above,
the additional thickness of cover specified in section -B may be reduced by half.
Thank you
# For reinorced concrete members of
marine structures totally immersed in sea water,
the cover shall be 40 mm more than that specified in section' A', but total cover should not exceed 75 mm.
#For reinforced concrete structures/ structural members, periodically immersed in sea water or subject to sea spray, the cover of concrete shall be 50 mm more than that specified in Section 'A', but total cover should not exceed 75 mm.
Generally 4-5 cover blocks are required per square metre of slab.
For concrete of grade M25 and above,
the additional thickness of cover specified in section -B may be reduced by half.
Thank you
Mukesh Kumar
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