Quality Tests on Cement at Laboratory and at Site

 

Nowadays, cement is an important material in the construction industry. It is primarily employed in masonry and concrete construction. The key portion of a structure’s strength largely depends on the standard of cement.

But once you purchase cement there’s a precise risk of quality variations in cement. That’s why it’s essential to check the cement to understand its quality not solely to make sure you’re obtaining what you paid for however conjointly to forestall the chance of a structural failure through the utilization of defective materials.

Strength, permanency of structure, and rate of setting of cement as per the demand of work are the basic attributes of cement we have to keep in mind while purchasing cement.

In this article, I am going to discuss some of the most important Quality tests on cement which are carried out in the laboratory.

The fineness test of cement is done to measure the mean size of cement grain or particles and surface area of the cement particles per unit mass. The Fineness test of cement is performed by sieving cement sample through standard IS sieve. However, increased fineness can lead to the consumption of more water for workability, resulting in a higher possibility of dry shrinkage.

These three methods are generally adopted and performed to measure the fineness of cement:

2. Consistency Test of Cement

The standard consistency of a cement paste is defined as that consistency which will permit the Vicat plunger to penetrate in the cement paste to a point 5 to 7mm from the bottom of the Vicat mould.  This test is performed to determine the quantity of water needed to produce a cement paste of standard consistency as per IS: 4031 (Part 4) – 1988.

Setting time of cement is divided into two categories:

• Initial Setting Time
• Final setting Time

Initial Setting Time of Cement:

Initial Setting time of Cement is the time period after which cement paste starts hardening.  For Ordinary Portland Cement (OPC) initial setting time is 30 minutes.

Final Setting Time of Cement:

Final Setting time of cement is the time at which the cement paste completely loses its plasticity and becomes hard. The final setting time for Ordinary Portland Cement is 10 hours (600 minutes).

The tests performed to measure the setting time of cement are:

• Vicat penetration test, and
• Gillmore needle method

4. Soundness Test of Cement

Soundness of Cement refers to the ability of cement paste to retain its volume, i.e. doesn’t undergo large volume change after being hardened. If cement paste undergoes volume change after setting will result in the development of cracks in the mortar or concrete. Therefore it is essential to test the soundness of cement.

• Le-Chatelier method, and
• Autoclave method.

5. Strength Test of Cement

The most common strength test of cement is the Compressive Strength Test and Tensile Strength Test.

1. Cement mortar cube test ( For Compressive strength)
2. Briquette test ( For Tensile Strength)
3. Split tensile test (For Tensile Strength)

6. Heat of Hydration Test of Cement

The heat of hydration test of cement methodology covers the determination of the heat of hydration of cement by measuring the heat of solution of the dry cement and the heat of solution of a separate portion of the cement that has been partly hydrated for seven and for twenty-eight days, the variation between these values being the heat of hydration for the respective hydrating period.

• Calorimeter method.

7. Specific Gravity Test of Cement

If any material having Specific Gravity greater than 1 (one), then it sinks in water because of the Specific Gravity of water is 1. We already know that the Specific Gravity of cement ranges from 3.1 to 3.16 gram/cc. That means cement is 3.16 times heavier than the water of the same volume. The IS code for the Specific gravity test is IS 2720- Part 3.

The tests performed to measure the Specific Gravity of cement are:

• Le Chatelier’s Flask method