USEFUL CIVIL ENGINEERING TIPS FOR SITE ENGINEERS:
1. GRADE OF CONCRETE:-
- M5 - 1 : 4 : 8
- M10 - 1 : 3 : 6
- M15 - 1 : 2 : 4
- M20 - 1 : 1.5 : 3
- M25 - 1:1:2
2. CLEAR COVER TO MAIN REINFORCEMENT:-
- Footings: 50 mm
- Raft Foundation (Top) : 50 mm
- Raft Foundation (Bottom): 75 mm
- Raft Foundation (Side) : 75 mm
- Beam: 25 mm
- Strap Beam: 50 mm
- Column :40 mm
- Slab: 15 mm
- flat Slab: 20 mm
- Staircase: 15 mm
- Retaining Wall: 20 – 25 mm
- Water Retaining Structures: 2 0- 30 mm.
- Maximum water absorption by bricks – 15%
- Compressive strength of bricks – 3.5 N/mm2
- Density Of Bricks- 1600-1920 Kg/m3
- Minimum thickness of slab – 125 mm
- Dimension tolerance for cubes – +2
- Maximum free fall of concrete – 1.50 m
- Lapping should not be used for the bars having larger dia than 36 mm.
- Binding wire required for steel reinforcement – 8 kg per MT
- 3 samples should be taken for every 100 m2 in core cutting test.
- Maximum chair spacing – 1 m.
- Minimum dia should be used in dowels rod – 12 mm.
- Hook for strriups (one side) – 9D
- No. of strriups = (clear span/spanning) + 1
- Length of main steel in cantilever anchorage – 69D.
- Minimum no. of bars in square column – 4
- Minimum no. of bars in circular column – 6
- Minimum dia of main bars and distributors in the slab – 8 mm.
- Maximum dia of main bars and distributors in the slab – 1/8 of slab thickness.
All reinforcement should be free from mill scales, loose rust, and coats of paints, oil or any other substances.
3. SETTING TIME:
- Initial setting time should not be less than 30 minutes.
- Final setting time should not be greater than 10 hours.
4. REQUIRED CURING DAYS:
- Super sulfate cement – 7 days
- Ordinary portland cement – 10 days
- Cement with minerals and admixtures – 14 days.
5. SLUMP VALUE (IS-456):
- Lightly reinforced concrete: 25 – 75 mm.
- Heavily reinforced concrete: 75 – 100 mm.
- Trench fill : 100 – 150 mm ( for in-situ & tremie).
6. CUBE SAMPLES:
- 1 – 5 m3 : 1 No.
- 6 – 15 m3 : 2 No..
- 16 – 30 m3 :3 No.
- 31 -50 m3 : 4 No.
- Above 50 m3 : 4 + 1 no. of addition for each 50 m3.
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