Basic Notes for Civil Engineers

Weight of steel for various diameters of bars
6 mm = 0.222 Kg
8 mm = 0.395 Kg
10 mm = 0.616 Kg
12 mm = 0.888 Kg
16 mm = 1.578 Kg
20 mm = 2.466 Kg
25 mm = 3.853 Kg
32 mm = 6.313 Kg
40 mm = 9.865 Kg

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 

Footings : 50 mm
Raft Foundation Top : 50 mm
Raft Foundation Bottom/Sides : 75 mm
Strap Beam : 50 mm
Grade Slab : 20 mm
Column : 40 mm

Design Mix
M10 (1:3.92:5.62)

Cement : 210 Kg/M3
20 mm Jelly : 708 Kg/M3
12.5 mm Jelly : 472 Kg/M3
River Sand : 823 Kg/M3
Total Water : 185 Kg/M3

Admixture : 0.7%

M25 (1:2.28:3.27)
Cement : 340 Kg/M3
20 mm Jelly: 667 Kg/M3
12.5 mm Jelly : 445 Kg/M3
River sand : 775 Kg/M3
Total water : 185 Kg/M3
Admixture : 0.6%
Fresh concrete density : 2414 Kg/M3
Note : sand 775 + 2% moisture, water 185-20.5 = 164 liters
Admixture : 0.5% is 100 ml