How to Test the Consistency of Cement
Definition: The standard consistency of cement paste is the level of water required, where the plunger infiltrates into the cement paste of about 5mm to 7mm from the base of the shape and in the other word consistency of cement is the base measure of water required to start a synthetic response among water and cement to frame a paste.
A Minimum quantity of water required to initiate the chemical reaction between water and cement to form a paste is known as consistency of cement. The cement consistency which will allow the Vicat plunger to penetrate to 5-7 mm point from the bottom of Vicat mould is known as standard consistency. For reference purposes, the standard consistency of a Portland cement fluctuates between 25–35%.
Significance: We as a whole realize that the strength of concrete relies upon the quality Cement. To get the necessary cement strength, we need to include the perfect measure of water. Water underneath standard security won't start the concoction response among water and cement, which will build the strength of cement.
Water less than the standard consistency would not initiate the chemical reaction between water and cement resulting in the strength of cement. Water more than the consistency results in excess water and strength reduction. That’s why it is important to know the standard consistency of cement material. On the other hand, overabundance of water over steadiness brings about abundance moisture and loss of strength. In this manner it is essential to know the standard consistency of cement.
Different tests on cement:
1. Fineness test of Cement by dry sieving method with 90 micron strainer
2. Adequacy test of cement by Le Chatelier
Reasons for the Test: We know that the cement we used on our site is mostly affected by the following:
1. Weather Conditions.
2. Excessive combination of Silica. One of the cement ingredients which determines the initial and final setting time of cement paste.
3. The fineness of cement.
4. Manufacturing Defects.
By Standardising the consistency of cement, we know how much water is required to produce an effective cement which will eventually produce good quality concrete. Standard Consistency of an ordinary Portland cement varies between 25-35%. That means we need 25% of water in volume to make a standard consistency of cement.
For Example, If we need to calculate the amount of water required for a 200 g of cement which has 30% consistency means then we need 200*30% = 60g water to prepare a standard consistency. This is what we are going to find in this test.
Test method of standard consistency of cement
Objective: The Aim of this test is to find the basic required quantity of water to form a cement paste as specified by IS Code 4031 (Part 4 – 1988) which the Vicat plunger will penetrate to 5-7mm point to the bottom of Vicat mould.
The whole test is conducted in a trial and error method. First, we assume some percentage as the standard consistency. Then we test it out against our Vicat apparatus. If the results agree with the assumption, we can conclude the test has succeeded. If not, we adjust the assumed value accordingly and test again.
IS 4031-Part 4: 1997
a. Weighing Balance of precision 0.01gm
b. Vicat apparatus with plunger
d. Measuring jar
e. Gauging towels
f. Evaporating dishg.
1. Keep up the testing room at a temperature and relative stickiness of 27±2°C and 65±5%.
2. Take around 300 gms of cement test in a dissipation dish and blend water roughly 25% by weight of cement.
3. Start the stopwatch at the hour of adding water to the dry cement. Care will be taken that the blending time isn't under 3 minutes or not over a short way from the hour of water adding to the dry cement.
4. Spot the form of the Vicat's apparatus on a nonporous plate and fill the shape with the paste.
5. In the wake of smoothing the outside of the paste, make it level with the head of the shape. Shake the form marginally to flush out the entangled air.
6. Spot it underneath the plunger of Vicat's apparatus and lower the plunger delicately to contact the outside of the test square.
7. Rapidly discharge the plunger, permit it to sink into the paste and record the entrance of the plunger from the base of the shape. In the event that this isn't in the middle of 5-7mm, take a new example of dry cement of the same weight and increment the level of water and record the infiltration of the plunger.
8. Continue rehashing the above paste with increment in water substance until the infiltration of plunger in the cement paste is in the middle of 5 to 7 mm.
Test Result: The perusing of vicat apparatus ought to have 5-7 mm for standard consistency.
Test Result Format for Consistency test