Civil engineer tips

GRADE OF CONCRETE:

M5 – 1 : 4 : 8

M10 – 1 : 3 : 6

M15 – 1 : 2 : 4

M20 – 1 : 1.5 : 3

M25 – 1 : 1 : 2

CLEAR COVER TO MAIN REINFORCEMENT:
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.

SETTING TIME:

Initial setting time should not be less than 30 minutes.

Final setting time should not be greater than 10 hours.

REQUIRED CURING DAYS:

Super sulfate cement – 7 days

Ordinary portland cement – 10 days

Cement with minerals and admixtures – 14 days.
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).

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