Some Important Codal Provisions To Be Remembered

  • Lapping is not allowed for the bars having diameters more than 36 mm.
  • For dowels rod minimum of 12 mm diameter should be used.
  • Longitudinal reinforcement of RCC column not less than 0.8% and more than 6% of gross C/S.
  • Minimum bars for a square column is 4 No’s and 6 No’s for a circular column.
  • The main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.
  • The minimum thickness of slab is 125 mm.
  • Dimension tolerance for cubes + 2 mm.
  • The freefall of concrete is allowed a maximum of 1.50m.
  • Water absorption of bricks should not be more than 15 %.
  • pH value of the water should not be less than 6.
  • The compressive strength of Bricks is 3.5 N / mm2.
  • In steel reinforcement binding wire required is 8 kg per MT.
  • In soil filling as per IS code, 3 samples should be taken for core cutting test for every 100m2.

Density of Materials

Bricks1600 – 1920 kg/m3
Concrete block1920 kg/ m3
Reinforced concrete2310 – 2700 kg/ m3

Curing time of RCC Members for different types of cement

Super Sulphate cement: 7 days
Ordinary Portland cement OPC: 10 days
Minerals & Admixture added cement: 14 days

De-Shuttering time of different RCC Members

RCC MemberDe-shuttering time
For columns, walls, the vertical formworks16-24 hrs.
Soffit formwork to slabs3 days (props to be refixed after removal)
Soffit to beams props7 days (props to refixed after removal)
Beams spanning up to 4.5m7 days
Beams spanning over 4.5m14 days
Arches spanning up to 6m14 days
Arches spanning over 6m21 days

Cube samples required for different quantity of concrete

Quantity of ConcreteNo. of cubes required
1 – 5 m31 No’s
6 0 15 m32 No’s
16 – 30 m33 No’s
31 – 50 m34 No’s
Above 50 m34 + 1 No’s of the addition of each 50 m3

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