12 Important Points to Remember For Civil Engineer About Cement

Raw material used for manufacturing of cement

  •    Limestone (Caco3)
  •    Sand (Sio2)
  •    Stale clay (SiO2, Al2O3, Fe2O3)

Chemical Composition

   Oxide Compound (in percentage)

  • Lime (Cao): 60-65%
  • Silica (SiO2): 17-25 %
  • Alumina (Al2O3): 3-8%
  • Iron (Fe2O3): 3- 8%
  • Magnesia (MgO): 0.5-4%

     Baogue Compound (in percentage

  •   Tricalcium Silicate: 25-40%
  • Dia calcium Silicate: 25-40%
  •  Tricalcium Silicate: 5-11%
  •  Tetra calcium Alumina Ferrite: 8-14%

Functions of Oxide compound

  • Lime (Cao): strength & soundness.
  • Silica (Sio2): strength.
  • Alumina (Al2O3): Quick setting
  • Iron Oxide (Fe2O3): Color to cement.

Function of Baogue Compound

  • Calcium Silicate (C3S): Early strength
  • Diacalcium Silicate (C2S): Slow heat of hydration
  • Tricalcium Aluminates (C3A): Increase the setting time.
  • Tetra Calcium Alumina Ferrite (C4AF): hydrates rapidly but less strength.

Read More:-The function of Different types of cement and their advantage and Disadvantage

 Calculation of Volume of 1 Bag (50 Kg) of cement in Cubic meters.

Density of cement: 1440 Kg/m3

Weight of 1 Bag : 50 Kg

We know the formula of Density,

 Density= mass (Kg) / Volume

 Volume = Mass (Kg)/ Density

                               = 50 / 1440 = 0.034722 cum.

Therefore, Volume of 1 Bag of cement = 0.034722 cum.

Calculation of Number of bags required in 1 cum

A number of bags of cement required in 1cum = Density/Weight of 1 bag of cement

Number of bags required in 1 m3 = 1440/ 50   = 28.8 (29 Bags).

Calculation of Volume of 1 Bag of cement in Cubic Feet

Let’s find the Volume of 1 Bag using basic mathematical formula

We know the formula of Density,

Density= mass (Kg) / Volume

 Volume = Mass (Kg)/ Density

                               = 50 / 1440 = 0.034722 cum.

Volume of 1 Bag of cement = 0.034722 cum.

As we know that 1 meter = 3.28 feet

So to convert Cubic meters into cubic feet

1cum = 3.28 feet x 3.28 feet x 3.28 feet

         = 35.3147 cubic feet.

So Volume of 1 Bag in Cubic feet= 0.034722 x 35.3147 =1.226 CFT.

Calculation of Volume of 1 Bag of cement in Liters

From above, Volume of one bag = 0.034722 cum

As we know that 1 m3 = 1000 liters.

Volume of 1 Bag in liters = 0.0347222 x 1000 = 34.7222 liters

Field Test

A field test is more important than laboratory results because it gives immediate results. It plays a crucial role in terms of strength and durability. There is a different practice to test the cement on site. Here is some applied method to check the quality of cement.

Check the Color:

Once the cement bags carrying vehicles are unloaded, Engineers should check the color. Make sure that the color should be uniform and grey.

  • The color of OPC is grey.
  • The color of PPC is Blackish.

Insert your palms inside the Bags:

Once you insert your hand in cement bags, you will feel smooth or cool when touched or rubbed in between fingers. If you feel cool then it indicates the quality of cement is good, if not which means it is not suitable for construction work.

Throw a small quantity of cement in Bucket:

If a small quantity of cement is thrown in a bucket of water, it should sink means the quality of cement is good. If it won’t sink that shows that it is not suitable for the preparation of concrete.

Check the lumps inside the bags:

It should be free from lumps because it affects the strength of concrete. IF bags containing lumps should be rejected for construction work.

Storage Specification

  • Keep the bags 1 foot from wall for the protection from moistures.
  • 15 Numbers of bags should be placed in one row.
  • Cement bags should be placed 15- 25 cm from the floor level. Make sure that it should be kept on wooden sleepers.
  • Bags should be stacked in 10-12 layers.
  • There should not be any opening in the storage room because to reduce the moisture.

Strength versus age of concrete

Concrete strength is directly proportional with time. As the time duration increasing, strength gained by concrete also increasing.

  • 1 days = 16% compressive strength.
  •  3 days = 45% of its Specified strength.
  • 7 days = 60% compressive strength.
  • 14 days = 90% compressive strength.
  •   28 days = 85% compressive strength.

Some Known Facts or information

  • 1 ton of cement: 20 Bags.
  • No of bags carrying capacity of Trucks: 250-300 Bags.
  •  Density of cement: 1450 Kg/cum.
  • Specific Gravity : 3.15.
  • Color of OPC : Gray
  • Color of PPC : Blackish.
  • Grade of OPC : Grade 33, Grade 43, Grade 53
  • Grade of PPC : Grade 33.
  • Initial setting time : 30 minutes
  • Final setting time of : 600 minutes.
  • Percentage of Gypsum added in Cement: 2-3%.
  • Acceptance Criteria of consistency of OPC is 25% – 33% of weight of the bag.
  •  Soundness should not be more than 10 mm.

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