### Some vital information and formulas for civil engineers This exclusive construction article is intended for civil engineering students. The article provides some vital information and formulas regarding weight of steel bars per meter, weight of engineering materials, standard conversion factors, concrete grades etc.

Weight of steel bars per meter

• For 6 mm dia bar, the weight will be 0.222 kg
• For 8 mm dia bar, the weight will be 0.395 kg
• For 10 mm dia bar, the weight will be 0.616 kg
• For 12 mm dia bar, the weight will be 0.888 kg
• For 16 mm dia bar, the weight will be 1.578 kg
• For 20 mm dia bar, the weight will be 2.466 kg
• For 25 mm dia bar, the weight will be 3.853 kg
• For 32 mm dia bar, the weight will be 6.313 kg
• For 40 mm dia bar, the weight will be 9.865 kg

The following formula is applied to find out the weight of steel bars:-

W= (D^2 x L)/162

Here, D denotes dia of bars and L denotes total length of steel bars for which the weight should be measured.

As for instance, if it is required to work out the weight of 20 mm steel bars, the calculation will be as follow :-

W = 20^2/162

W = 2.466 kg/meter

A conversion factor stands for a number that is employed to transform one set of units to another, by multiplying or dividing. While doing a conversion, the exact conversion factor to an identical value should be applied. As for instance, to transform inches to feet, the exact conversion value should be 12 inches equivalent to 1 foot.

Given below, the details of standard conversion factors:-

• 1 inch = 25.4 mm
• 1 foot = 0.3048 m
• 1 yard = 0.9144 m
• 1 meter = 3.28 ft
• 1 mm = 0.0394 inch
• 1 mile = 1.6093 km
• 1 newton = 0.10 kg

Concrete grades are represented as M10, M20, M30 as per their compressive strength.

The “M” stands for Mix design of concrete succeeded by the compressive strength number in N/mm2

“Mix” belongs to the relevant ingredient proportions which are Cement: Sand: Aggregate or Cement: Fine Aggregate: Coarse Aggregate.

If we refer to M15 concrete, it signifies that the concrete contains 15 N/mm2 characteristic compressive strength at 28 days.

For M5 grade of concrete, mix proportion is 1:4:8

For M10 grade of concrete, mix proportion is 1:3:6

For M15 grade of concrete, mix proportion is 1:2:4

For M20 grade of concrete, mix proportion is 1:1.5:3

For M25 grade of concrete, mix proportion is 1:1:2

Given below, the unit weight of various types of engineering materials.

• Bitumen = 1340 kg/m3
• Cement = 1440 kg/m3
• Cast Iron = 7650 kg/m3
• Steel = 7850 kg/m3
• Ice = 913 kg/m3
• Petrol = 690 kg/m3 