DERIVATION FOR D2/162

We know the formula D2/162 which is being used for calculate unit weight of reinforcement per meter.
Here I am willing to explain how it has been arrived D2/162 (Note: D unit is in MM)
Weight of bar per meter = Area of steel bar X Density of steel x Length of bar
= (3.14 x D2/4) x 7850 kg/m3 x 1 m
= D2 X 6162.25/(1000x1000)
= D2 X (0.006162)
= D2 X 1/(0.006162)-1
= (D2/162.28)

The actual value is D2/162.28

Kindly note that this function is only applicable for circular shape steel which density is 7850kg/m3

HOW TO CALCULATE INGREDIENTS OF RCC

For an Example,
Let us consider grade of concrete as M15 (Mix 1:2:4)
Let,
Quantity of concrete – 1 m3
Normally we consider 90% of coarse aggregate in total quantity of concrete, Hence
20mm coarse aggregate – 0.90 m3
Fine aggregate = 0.90 m3 x 2/4 à (2 part of fine aggregate / 4 part of coarse aggregate)
= 0.45 m3
Cement = 0.45 m3 x ½ à (1 part of cement / 2 part fine aggregate)
= 0.225m3
= 0.225 x 1440 kg/m3
= 324 kg
Note: 1440 kg is the density of cement