Guidelines to provide concrete cover for reinforcement in slab, footing, beam & column
Concrete cover: Concrete Cover is arranged for the reinforcement in Reinforced Cement Concrete. Cover means the spacing among the exterior surface of the concrete to the inserted reinforcement.
Benefits of arranging Concrete Cover: The purpose of covering is to provide protection against erosion. Reinforcement is susceptible to erosion and fire for atmospheric conditions. In case of improper cover erosion and cracks may occur in hardened RCC.
Covering is arranged for each and every component of the building (Slabs, Beams, footings) where the reinforcement is applied. The covering blocks are utilized to retain the reinforcement in exact position as well as providing a covering for reinforcement.
Several Types of Concrete Cover Block: Depending on the type of materials applied, the following types of covering blocks are commonly found -
1. Wooden concrete cover Block
2. Steel concrete cover block
3. PVC Block
4. Cement Masonry concrete cover block
5. Aluminium Block
Conditions for Concrete Cover: Covering differs based on the dimensions of the components (Slab, beam, column, footings, etc.) The conditions for arranging covering in RCC are provided below -
Condition - Covering
When the length of the item is ≤ 0.3 1 - 1" or 25mm or 0.025m
When the length of the item remains ≥ - 0.6m then 4" or 100mm or 0.1m
From above, the maximum concrete cover remains 0.1m or 100cm
1. Concrete Cover in Columns / Beams: The length and width of the column should be 0.5m and 0.45m. The covering for reinforcement in the column should be 0.050m from all sides and similar reinforcement should be designed accordingly. The Dimensions of Reinforcement in the column should be 0.40m and 0.35m.
Suppose the length and width of the column are 0.40 and 0.25. Covering should be equal. Consider the minimum dimension from the two dimensions i.e. 0.25. For 0.25m the covering of 0.025m should be provided. So, the covering of 0.025m is arranged in all the sides. Therefore, dimensions of reinforcement is 0.35m and 0.20m.
Total Length of Stirrup is 2x [0.35+0.20]+ 9D x 2 (hook length)
2. Concrete Cover for Slabs: Suppose, the length and width of the slab are 1.3m and 1.0m. The covering of 0.1m is arranged when the length of the bar is in excess of 0.6m. Use the same condition as mentioned. The covering of 0.1m is arranged from all the sides of the slab.
3. Concrete cover for footings: Suppose, the dimensions of Footing are 0.7m and 0.6m. To length and width of Mesh (reinforcement) utilized in footings are acquired by subtracting the cover. Use the similar principle as above. As per the condition, a concrete cover of 0.1m is subtracted from all the sides. Therefore, the dimensions of reinforcement are 0.5m and 0.4m.