There is a massive space for construction work in a developing country like India. And concrete seems to be a bit synonymous with construction work. The essential ingredient in concrete is cement, and cement quality directly affects the quality of concrete. Let us know how we can check cement during the construction work. The testing/testing of cement can be divided into two categories: Field testing and laboratory testing.
Before using cement in essential works, it is examined both physically and chemically. And only if the results are as per the prescribed Indian standards are used. The cement used in these essential works cannot be tested by field testing alone. But in smaller functions less critical, we can try cement on the field.
- Cement should usually be greenish-grey and should not show any lumps in it.
- Putting the hand in the cement bag gives a cold feeling, and even touching it should not cause any lump in the hand.
- Taking a pinch of cement between two fingers should not make it feel gritty.
- Take a fistful of cement, and when thrown into a bucket full of water, the corn of the cement should float for some time before sinking.
- Take 100 grams of cement and mix it with a bit of water to make a stiff paste; now make a flattened cake with sharp edges from this paste. Place this cake paste on the surface of the glass and put it in water. The shape of the paste should remain when put in water, and after 24 hours, it should become something solid.
Laboratory Testing (Laboratory Testing)
Laboratory testing of cement can be divided into two parts: physical testing and chemical testing.
The tests that come in the physical laboratory examination of cement are as follows:
Fineness Test of Cement: The particle size of cement means a lot for its characteristics. Over time, cement continued to grow, and fine cement particles were also manufactured. But why is it so important? Let's know what the fineness of cement is, its specialty, and how to see the fineness of the cement. If the two types of cement are made of the same chemical composition but their particles have different sizes, their characteristics vary significantly. A finer cement has a higher surface area, due to which, when mixed with water, there is more area for hydration, and the strength of the cement also increases rapidly. The surface area of the particles in 0.1 kg of cement is called the fineness of the cement. As per the Indian Standard Code, the ordinary portland of cement should have a minimum fineness of 225 square meters per kilogram of all the three grades of cement (33 grades, 43 grades, 53 grades.
Soundness: It is essential to maintain its shape after the cement hardens. After solidification, expansion is often observed in the cement, which also changes its shape, and directly affects the durability of the concrete. The ability of the cement to maintain its volume after it has solidified is called soundness. Before using cement in construction works, it becomes essential to measure the quality of its soundness. Earlier, all kinds of tests were included in the same code (IS code 4031) to evaluate the physical properties of the hydraulic cement. But to facilitate the use of modifications to the code in the future, all the tests were divided into separate parts. Thus, this code was divided into 13 parts. The third of these is designed to determine the IS Code 4031-Part-3 soundness.
Compressive Strength of Cement: It is an important task to check cement before its use during construction works. The cement compressive strength test is the most important of the different types of cement tests. Therefore, in the laboratory examination of the cement used before starting essential tasks, find out its compressive strength. Standard sand is used along with cement to test cement compressive strength as the use of cement alone leads to the problem of excessive shrinkage of cement and cracks. Cement is divided into three grades based on strength: 33rd-grade cement, 43rd-grade cement, and 53rd-grade cement, whose pressure capacity of 28 days when tested as per Indian standards is 33MPa, 43MPa, and 53MPa, respectively. After selecting the cement grade as per the mix design, the compressive strength of cement has to be laboratory checked as per the Indian Standard Code.
Initial and Final Setting Time of Cement: Both the initial setting time (IST) and final setting time (FST) of cement plays an essential role in the quality of the construction. After adding water to the cement, it starts to solidify in a while, and these few delays play a vital role in the construction work, which we also call the setting time of cement. Within this time, we have to deliver concrete or some other material made of cement to its final form. The setting time of the cement may be different in different types of cement. Therefore, one of the many checks of cement used in concrete, etc., is also its setting time before designing it. To determine the setting time of the cement, the time of its solidification is divided into two parts the initial and final setting time of cement.
Since high-quality cement has its chemical structure behind it, the limit of its chemicals has been set according to the type of cement as per Indian standards. For example, what should be the chloride content in cement, magnesia, etc? Further details can be obtained from The Indian Standard 269, valid for all Ordinary Portland Cement types (OPC). Before purchasing the cement used in the vital project, its manufacturer gets approval from the client. The cement company issues an MTC (Material Test Certificate) with each lot of cement. The information on testing the cement made in the factory is available every week. It has often been seen that a third party also tests cement for cross-checking. And along with this, physical tests of cement can also be done in the quality laboratory of the project site.