Consistency test of cement by vicat apparatus is required to get percentage of minimum required water content on which the vicat plunger penetrates 5 to 7 mm in cement paste from the bottom of the vicat mould.
We should confirm that what quantity of water is being mixed with cement for cement consistency test it’s sufficient or not for reaction of cement ingredients like Calcium oxide CaO, Silicon dioxide SiO2, aluminium oxide Al2O3 etc.
Consistency Test of Cement IS Code
For determination of consistency test of cement or test procedure of standard consistency test of cement we follow IS 4031 part 4.
Apparatus and Tools Required for Cement Consistency Test
1. Vicat apparatus ( it shall confirm IS 5513-1976 revised in 1996)
What secret in IS 5513-1996
Just take a look, I got this.
It’s all about dimensions of Vicat apparatus components like plunger, movable rod, graduated scale, vicat mould and it’s needles.
So now we assume that your all doubts are cleared about dimensions of vicat apparatus components.
2. Two numbers of Trowel ( for mixing cement and water ).
3. One non-porous plate on which cement and water shall be mixed.
4. Weighing balance with at least 0.1 gm accuracy because of permissible variation on 300 gm is +/- 0.3 gm, and for 500 gm is +/- 0.35.
5. Hand gloves for your safety.
Precautions before proceeding Consistency test
1. Vicat apparatus and it’s components shall be clean, mainly needle.
2. De-shuttering agent ( lubricant or grease ) shall be applied inner surface of vicat mould.
3. Non-porous plate and trowels shall be clean before test, we should not use trowels and non-porous plate in wet condition, this moisture may affect on test result.
4. Temperature of room where cement consistency test is going to be done shall be 27 +/- 2 degree Centigrade, means between 25 to 29.
5. Like temperature, Humidity is also an important factor for consistency test of cement, humidity shall be 65 +/- 5 percent, means between 60 to 70.
6. Ensure zero on graduated scale with empty vicat mould and base plate.
Procedure of Consistency test
1. Take 400 gram of cement and 25 percent water of cement weight if you are new to this cement, means if you are testing consistency this cement first time and you do not know about it’s property, so you may start with 25 percent water because any cement consistency comes between 25 to 35 percent.
cement = 400 gm, water = 400*25% = 100, mostly Ordinary Portland Cement consistency comes between 27% to 30%.
2. Water increment will be 0.5 percent like first 25.0 %, 25.5 %, 26.0 %, 26.5 % …….
3. Mixing time is 3 to 5 minutes, it will start when you adding water in cement and finish when get the penetration on the graduated scale.( important )
4. Start stop watch and add water in cement simultaneously.
5. Mix properly by using both trowels, its very important.
6. After mixing well, vicat mould shall be filled by that cement paste by slightly shaking or slightly strucking the mould. Be ensure that no voids is in paste.
7. After filling mould with cement paste, vicat mould with paste shall be placed in vicat apparatus.
8. Fix consistency needle in vicat apparatus before start the test.
9. Lower the vicat plunger slowly until the consistency needle bottom point touches the cement paste top surface filled in vicat mould.
10. Release the plunger quickly, let it sink in paste, when it stops sinking ( nearly 3 to 4 seconds ) note down the reading from graduated scale.
11. Increase water content 0.5 percent until you get 5 to 7 mm reading on graduated scale.
12. Note down that water content on which you got penetration between 5 to 7 mm.
Cement Consistency Limits
Consistency limits of cement is 5 mm to 7 mm.
Report & Calculation of Consistency test of cement
sr. no. cement (gm) water (%) penetration (mm)
1. 400.0 27.0 12
2. 400.0 27.5 8
3. 400.0 28.0 6
Standard consistency – 28.0 %