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Standard Consistency Test on Cement | Definition, Apparatus, Procedure, Calculations

“What you get by achieving your goals is not as important as what you become by achieving your goals.”

Finding out the factors like Initial setting time, Final setting time, and soundness of cement a parameter named Standard Consistency is used. Standard Consistency is the amount of water required to make cement paste plastic.

This article gives detailed explanation on Standard Consistency Test of Cement and how to calculate it?

What is Consistency of Cement?

Consistency of Cement is amount of water required to initiate the chemical reaction between cement and water to make the uniform cement paste.

Define Standard Consistency of Cement?

Standard Consistency of Cement is defined as Consistency which will permit Vicat plunger with 10mm diameter and 50mm length to penetrate to a depth of 33-35mm from top of the mould.

Standard Consistency of Cement can also be defined as Consistency of cement which will permit Vicat plunger to penetrate to the point 5-7mm from the bottom of the mould.

Also Standard Consistency means the amount of water required to make Cement Paste Plastic.

What is the Importance of Consistency in Cement?

Factors affecting the strength of concrete tells us that Material used and water-cement ratio are some of the major factors that affects the strength of concrete. Cement and water are the major materials in concrete.

To attain the design strength we need to add right amount of water in concrete. Adding water less than Standard Consistency will provide less suitable environment for water cement reaction and ultimately less heat of hydration and less strength.

Addition of water more than the Standard Consistency can result in segregation and also reduction in strength.

To avoid these kind of situations it is important to know the Standard Consistency of Cement.

Significance of Standard Consistency of Cement?

Standard Consistency of Cement helps us choose the right amount of water for producing effective concrete which will ultimately result in higher strength.

Note: Standard Consistency of an OPC varies between 25-35%. That means we need a minimum of 25% of the water in volume to make a standard consistency of cement depending on the cement type.

Lets assume Cement we got is having Standard Consistency of 30% and we have to calculate amount of water for 100 gm of cement then

100 x 30% = 30gm

That means 30gm of water is required to produce a Consistent paste of 100gm of cement.

Determination Standard Consistency Test on Cement

Aim:

To determine quantity of water required to produce a cement paste of Standard Consistency.

Apparatus:

1) Vicat Apparatus:

A device used to determine Standard Consistency and Setting Times consists of rod weighing 300 grams, having a needle at one end and supported in the frame with Graduated scale for measuring the Penetration. Also having a mould to put the cement.  

2) Plunger:

It is small rod type needle made of Polished Brass with 10 ± 0.05 mm diameter and 50mm length with projection at upper end. The lower end is flat..  

3) Vicat Mould:

Vicat mould is having internal diameter 80 mm and 40 mm height. With non-porous base plate is provided at the base of the mould. Mould is having suitable clamping ring.  

4) Weight Balance:

To take the weight of Sample of Cement. It should at least be with least count of 1 gram.  

Procedure:

  1. Firstly take 300 grams of Cement in a pan and mix with the known percentage of water by weight of Cement, assume starting from 26% and then increase it by every 2% until the normal Consistency is achieved.
  2. With continuous mixing.
  3. Prepare the paste within the time of Gauging of 3 minutes, not more than 5 minutes, Gauging shall be completed before any sign of setting occurs. Gauging time shall be counted from the time of adding the water to Cement and until filling the paste into the mould.
  4. Now fill the paste into the Mould with a nonporous plate below.
  5. Level and Smoothen the surface of the paste.
  6. Place the mould in the Vicat Apparatus allow the Plunger to touch the surface of paste and then release the plunger allowing it to freely sink into paste.
  7. Repeat this procedure with varying water content until the amount of water necessary for Standard Consistency is found.

Precautions:

  • Time of Gauging should not be less than 3min and in any case not more than 5min.
  • Plunger should be cleaned before any repetition.
  • Vibrations to the table should be avoided it will allow the cement to set and harden early.
  • Test should be conducted at room temperature 27oC +/- 2oC

Figure:

Observation Table:

Sr. No.Weight of cement (gram)Percentage of water by dry cement (%)Amount of water added (ml)Penetration (mm)
1
2
3
4

Calculations:

Standard Consistency Formula:

Standard Consistency = (Quantity of water for 33 mm to 35mm penetration from top/Weight of cement) X 100  

Results:

Standard Consistency of given Cement is : __________                  

Video Explanation on Standard Consistency Test of Cement

FAQs on Standard Consistency Test of Cement?

What is Gauging Time?

Gauging Time is a time span between the addition of water to cement and filling the mould.

What do you mean by normal consistency?

Standard Consistency is also called as Normal Consistency and defined as amount of water required to make Cement paste plastic.

What is the normal consistency for OPC?

Standard Consistency of an OPC varies between 25-35%. That means we need a minimum of 25% of the water in volume to make a standard consistency of cement depending on the cement type.


Consistency Test of Cement PPT


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