Cement is a very important component of our economy and plays a major role in all major construction activities throughout the globe. Be it roads, houses, or buildings, cement is an essential. And since it is such an important part of our life, it is important to keep a check on the quality of the cement used for our safety and security. Because if not checked, it can turn out to lethal for the entire population. So let us have a look at some of the key tests that are run on cement to certify its quality.
Consistency test: One of the most important tests, the consistency test is conducted using the Vicat’s apparatus, one of the leading cement testing equipment. Conducted at a constant temperature of 25 degrees Celsius or 29 degrees Celsius with constant humidity of 20%, it is conducted thrice at a water about 25-27% the total weight of the cement. The test is defined by the amount of water that allows the plunger (of diameter 10mm and length 50mm) to penetrate 33-35mm of paste within 3-5 minutes of mixing.
Fineness Test: Fineness of the particles if cement is a very important aspect and defines the speed of strength development of particular cement. The finer the particles, the quicker is the development of strength due to vast surface area. Fineness is responsible for hydration, evolution of heat, and gain of strength. The fineness can be tested through the air-permeability test or the Sieve test.
Heat of Hydration test: Cement is formed basis a chemical reaction and during its hydration, the reaction produces heat. This heat can raise the temperature to as high as 50 degrees Celsius. To avoid this situation, low-heat cement is used in industries. To ensure low-heat properties of cement the heat of hydration test is used. Using a simple cement testing equipment, the calorimeter, the test is carried out and an ideal quality of cement will not produce more than 65 calories per gram of cement in a span of 7 days and 75 calories per gram in 28 days.
Tensile strength test: Tensile strength is the most important property of cement since it is used to hold structures. Testing the same is very important. Using a tensile testing machine and a cement-mortar briquette the test is carried out. The mixture contains 8% water and the rest is sand and cement in a ratio of 3:1. This mixture is then kept in the briquette for 24 hours at a constant temperature of 25 or 29 degrees and 90% humidity. The final test results include average readings of 6 briquettes after 3 and 7 days.
Setting time test: Based on the consistency test, setting time test also uses the Vicat’s apparatus and is used to measure the setting time of the cement. It measures the initial setting time and the final setting time. During the initial test, a 1mm square needle penetrates 33-35mm of the paste. The time taken is recorded as the initial time. After attaining hardness, the same needle cannot penetrate beyond 0.5mm, the time taken to reach this limit is recorded as the final setting time.
So these are the five most important tests to check the qualities of cement and certify it for industrial use.