Overview
Standard consistency of a cement paste is defined as that consistency which will permit a vicat plunger having 10 mm dia and 50 mm length to penetrate to a depth of 33-35 mm from top of the mould.
Apparatus
Measuring Instruments
| NAME | CAPACITY / RANGE / SIZE | ACCURACY / LEAST COUNT |
| Vicat apparatus | Should be made as per IS:5513 | — |
| Balance | 1000 g | 1 g |
| Measuring cylinder | 100 ml | 1 ml |
Other accessories
| Tray, glass plate |
Environmental Condition
| Temperature | 27 ± 20 C |
| Humidity | 65 ± 5 % |
Procedure
- Take 400 g of cement and place it in the enameled tray.
- Mix about 25% water by weight of dry cement thoroughly to get a cement paste. Total time taken to obtain thoroughly mixed water cement paste i.e. “Gauging time” should not be more than 3 to 5 minutes.
- Fill the vicat mould, resting upon a glass plate, with this cement paste.
- After filling the mould completely, smoothen the surface of the paste, making it level with top of the mould.
- Place the whole assembly(i.e. mould + cement paste + glass plate) under the rod bearing plunger.
- Lower the plunger gently so as to touch the surface of the test block and quickly release the plunger allowing it to sink into the paste.
- Measure the depth of penetration and record it.
- Prepare trial pastes with varying percentages of water content and follow the steps (2 to 7) as described above, until the depth of penetration becomes 33 to 35 mm.
Calculation
Calculate percentage of water (P) by weight of dry cement required to prepare cement paste of standard consistency by following formula, and express it to the first place of decimal.
Where,
W=Quantity of water added
C=Quantity of cement used
Precautions
- Gauging time should be strictly observed
- Room temperature should be well maintained as per test requirement.
-
All apparatus used should be clean.
- The experiment should be performed away from vibrations and other disturbances.
Technical Discussion
- This test helps to determine water content for other tests like initial and final setting time, soundness & compressive strength.
| NAME OF TEST | AMOUNT OF WATER REQUIRED |
| Soundness (Le-chatelier method) | 0.78 P (P=Consistency of standard cement paste) |
| Setting time | 0.85 P (P=Consistency of standard cement paste) |
| Compressive strength |  of combined mass of cement and sand. |
- Consistency refers to the relative mobility of a freshly mixed cement paste or mortar or its ability to flow. For a mortar the standard consistency is measured by flow table test.
- Generally the normal consistency for OPC ranges from 26 to 33%.
Test Standard Reference
- IS:4031(Part 4):1988-Methods of physical tests for hydraulic cement (Determination of consistency of standard cement paste)
Related videos
Factor 0.85 for Initial setting time how it is derive,
Factor 0.78 for Soundness how it is derive,
Comp. strength (P/4+3), 4 and 3 how it is derive
Insoluble residue for PPC max= X+4*(100-X)/100, 4 how it is derive
hi,
you mentioned the formula P=W/C*100. Which IS codebook mentioned that formula.
Thanks sir for useful information
Why we takes 78% water of NC for le chatelier test???
what is the standard consistency prepared cement paste with w/c ratio add minimum to maximum % of water by cement weight
Does 100 ml of water weighs same as 100 gm of water?
VERY USEFUL ARTICLE
Ur doing good job , but from this some of our doubts are not clear completely
Sir
I’m doing my project related to phospho gypsm. How can i find out the standard consistency of phospho gypsm? Is it same as for cement?
Is the consistency 35% for OPC 43 grade of cement is correct. As the value lies in between 25% to 33%
In our Lab Consistency Test for OPC 43 grade was carried out it came 35%.
Is it correct, as because the standard value lies in between 25% to 33%
why we take water content in setting test of cement lesser than the consistency value?
0.85 is it a factor!?? How to calculate it….
Hii iam Rajesh
We know
The percentage of water is added for initial setting time is 0.85p
Take an Eg :
Cement =1000 g or 1kg
Water required =0.85p ×wt.of cement
=0.85×0.25×1000
=212.5ml of water added
Tanq
Hii iam Rajesh
We know
The percentage of water is added for initial setting time is 0.85p
Take an Eg :
Cement =1000 g or 1kg
Water required =0.85p ×wt.of cement
=0.85×0.25×1000
=212.5ml of water added
Tana
Hello Sir,
my standard consistency is 29%,but the depth of penetration is 29mm.Is it the correct result?
Correction please.
Plunger diameter =1mm rather then 10mm
Do correction asap?
1mm sqaure needle is used for initial setting. 10mm needle is used for normal consistency test.
Dear
Sir Please suggest me about Concistency Related Trouble . I want to know about .85 times , what is it???? please help me
Thanks& Regards .
Lalan Kumar Asst. Lab Tech
Sir i m doing project on geopolymer using fly ash but i dont know how to find the normal consistency of fly ash i tried as like cement but its taking the water around 80% is it right or how much should be the maximum percentage ?
Why 25% of water we adding.plz help me out
Same dout pls help me
Based on trial and error we get the standard value. that is, in between 25% to 33% of water (by weight of the cement), we will achieve the standard consistency for different type of cement.
(Note: Consistency means, Amount of water required to form uniform cement paste)
what is the standard consistency of cement paste?why we are determining the consistency of cement?
what is the logic behind (P/4+3)% of combined mass of cement and sand?
Okay I got the consistency part.
But when I go for Initial Setting Time or Finap Setting time, the amount of water to be added is mentioned as “0.85P”
So my doubt is, If I am taking 100gm of cement and amount of water as “22.1”gm (0.85×26) it is OK.
But if I take larger amounts for eg. 2000gm of cement, will amount of water according to 0.85P be “22.1gm” ???
But that will be too small amount isn’t it??
Plz help…..
0.85 times the water required in ml is the equation for water demand for IST and FST. Hence you need to re-estimate the water qty when any changes occur in cement qty.
water required for 100 gm cement will be different from water for 200 gm cement as it is to be as per standard consistency (5-7cm in Vicat Apparatus).
0.85*P this is new percentage of water to be added
So for 2000 gms u need (0.85*P*2000) ml of water
Okay I got the consistency part.
But when I go for Initial Setting Time or Finap Setting time, the amount of water to be added is mentioned as “0.85P”
So my doubt is, If I am taking 100gm of cement and amount of water as “22.1”gm (0.85×26) it is OK.
But if I take larger amounts for eg. 2000gm of cement, will amount of water according to 0.85P be “22.1gm” ???
But that will be too small amount isn’t it??
Plz help…
Why the penetration limit of 5-7mm fixed in consistency?
Bcz, that indicates that chemical bonds are taking place in the mixture and the cement is now becoming solid.
And usually it happens in about 10 minutes.
Do you have any literature supporting it….
How we have to multiply weight of cement to .85P cuz it state .85P by weight of cement…shouldn’t we divide .85P by cement weight
Why the penetration limit 5-7mm fixed in consistency test?
test procedure will repeat untill get the reading 5 to 7 mm instead of 33 to 35mm
when we taking reading from bottom of the mould then it should come 5 to 7 mm (confirming to IS 4031 part 4 ). and above he is clearly mention that he was takes reading from the top of mould.
why 25% of water..?
Good. ….