Cement tests are conducted to determine the durability and distinctive characteristics of cement. Today, several cement tests are used to evaluate the quality of cement.
Various Cement Testing Methods are used to determine the properties of cement, such as its strength, consistency, specific gravity, and fineness. Before using cement in construction, it’s crucial to test the quality of cement and material.
Different methods for testing the strength of cement
Fineness test of cement
- This cement test is done to make sure the cement is ground properly
- The fineness of cement manages the hydration rate, heat evolution rate, and the gain of strength rate
- The sieve and permeability apparatus tests can be used to determine the fineness of cement particles.
Learn about: specific gravity of cement
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Sieve Test
The air-set lumps are broken when we sieve cement continuously for 15 minutes in a vertical and circular motion. The leftover material on the sieve is measured, and it shouldn’t be more than 10% of ordinary cement. The sieve Test is a relatively rare test of cement.
See also about: Cement design
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Air Permeability Test
A cement test known as Blaine’s Air Permeability Test is used to determine the surface area of cement. The total surface area is given in sq cm/g. Therefore, a finer particle will have a larger surface area.
Understanding cement performance through testing
Cement performance is of utmost importance so that construction is perfect. For this rigorous testing is done to determine the various factors. Mentioned below are the
Consistency test of cement
- The cement setting time is determined using the consistency test.
- Vicat’s apparatus is the tool used to carry out this cement test.
- A Vicat plunger with a diameter of 10 mm and a length of 50 mm can go through a depth of 33 to 35 mm after being mixed for three to five minutes. This is how the consistency of cement paste is measured.
- You must perform this test three times, mixing the cement with changing amounts of water each time, ranging between 24% and 27% of the cement’s weight.
- Maintaining a steady temperature between 25 and 29 degrees Celsius and a humidity of 20 percent consistently.
Compressive strength test
- This cement test is performed to ascertain the cement’s compressive strength.
- A 1:3 ratio is used to prepare the cement and sand mortar.
- A ratio of 0.4 water to cement is applied to the mortar.
- In moulds, the mortar is placed. The moulds are made of metal, and the test specimens are in the shape of cubes. Cement is needed in quantities of 185gm and 235gm for cubes of 70.6mm and 76mm, respectively.
- The moulds are then placed in a wet room for 24 hours after the mortar has been compacted for 2 minutes in a vibrating machine.
- After being taken out of the moulds, the specimens are immersed in clean water to cure
- At the end of 3 and 7 days, in a compression testing machine, the cubes are tested. Hence, compressive strength was discovered.
Setting time
- This cement test is used to find cement that has deteriorated from storage. To determine the initial and ultimate setting times, the testing is done.
- The Vicat mould is filled with cement mixed with cement paste and water.
- The Vicat apparatus’ moving rod is connected to the square needle.
- The needle is shortly released, and the cement paste can now be penetrated. The needle initially penetrates thoroughly. Repeating the process until the needle does not entirely penetrate is done at regular intervals. (5 mm or more from the bottom)
- Initial setting times for low-heat cement are 60 min. And <30 min. for ordinary Portland cement, respectively.
- The cement paste is prepared as above and filled in the Vicat mould.
- The Vicat apparatus’ moving rod has a needle with an annular collar attached.
- It releases the needle gently. It is noted when the collar fails to leave an impression on the test block, but the needle does one.
- The difference between the time cement was added to water and the time noted in the previous step is the ultimate setting time, equal to <10 hours.
Soundness test
- This test’s objective is to find any uncombined lime that may be present in the cement.
- Cement paste has been prepared.
- After being set in place, the mould is filled with cement paste.
- The water is cleaned of the mould, and it is then given time to cool.
- Another measurement is made of the distance between the indicator’s points. The difference between the two readings denotes cement expansion, and it shouldn’t use 10 m.
With the Le Chatelier method, cement samples contain lime and uncombined magnesia. The soundness of cement is defined as its ability to maintain its volume after hardening. A lack of lime in cement causes it to set more quickly, but too much lime causes the cement to expand.
Tensile strength test
- This test once indirectly determined the cement’s compressive strength cement.
- The mortar of cement and sand is made.
- To the mortar, water is added.
- In moulds, the mortar is placed. Then, a little mortar mound is created at the mould’s top. For briquettes, repeat the same procedure.
- The briquettes are gently removed from the moulds after being kept damp for 24 hours.
- The briquettes are examined in a testing apparatus after three and seven days, and the average is determined.
The heat of hydration cement test
- The hydration cement test is performed using a calorimeter and the concept of determining heat gain.
- Due to the chemical reactions taking place, this test generates a significant quantity of heat up to 50 °C
- This test uses low-heat cement to prevent such a significant change in .heat
- For this test, 27°C is the standard temperature.
- The heat released from hydrated cement – heat released from unhydrated cement is the equation to calculate the heat of hydration.
Specific gravity cement test
The specific gravity of a material informs us about its behaviour with water. It floats on water if the value is less than 1 for any substance. The material will sink into the water if the value exceeds 1. Hence, specific gravity tells us if a substance is lighter or heavier than water.
Kerosene is used in place of water to determine cement’s specific gravity (Sg) because cement hydrates to create calcium oxide. In this cement test, the following happens:
- A Lechatlier flask is dried and weighed to conduct this test. W1 is used to denote the weight.
- The cement weighs 50g after being added to the flask. Therefore, it is indicated as W2 for this weight.
- The flask is filled with kerosene to the neck and mixed with no air bubbles remaining. This is a weight marked as W3.
- The flask is then emptied, filled with kerosene, and weighed. This weight is denoted as W4.
- The values are placed in this equation with Sg of kerosene as 0.79 g/cc, Sg = (W2 – W1) / [ (W2 – W1) – (W3 – W4) ✕ 0.79 ].
Chemical composition cement test
Different tests are used to identify the components that make up cement. The requirements of the cement’s chemical composition in the IS Codes are:
- Magnesia must not exceed 5% of the total weight.
- Insoluble residue cannot weigh more than 1.5% of the total weight.
- The sulphur content of the tidal must be less than 2.75%.
- Less than 4% in total loss on ignition is required.
- LSF (lime saturation factor) should be greater than 0.66 but less than 1.02.
- The proportion of iron oxide to alumina should be greater than 0.66.
Field test of cement
On-site cement field tests are conducted to assess the cement’s quality quickly. The condition of the cement is assessed using a variety of tests, including
- Ensure to check the cement bag’s manufacturing date
- Having a consistent colour for the cement (grey with a shade of green).
- It must not contain cement that has hard lumps from absorbing air moisture.
- Due to hydration, the cement bag’s inside must be warm.
- When rubbed between the fingertips, the cement paste must feel smooth.
- Before ultimately sinking, the cement must float on the water.
- Due to the cut and pounded clay, cement paste must smell earthy.
- After being submerged in water for three days, a cement block should not crack when a uniform is placed on top.
The importance of testing cement before construction
The cement’s quality significantly influences your home’s longevity. Different cement types can enable you to build a better building and save money. However, you must choose cement with exceptional caution because it must be compatible with your construction goals. Engage in a detailed discussion with your engineer and select a quality cement after doing cement tests.
Why should we be open-eyed during the process of construction?
As a prospective homeowner, you must ensure that the cement and other construction materials you choose are of the highest calibre and should not be substituted with less expensive options. To reduce construction expenses and boost their profit margin, it is common practice among construction experts to use low-quality cement and blend it with other inexpensive materials. However, it is harmful since it may eventually shorten your home’s lifespan and weaken its construction. To ensure that all raw materials, from cement to a small screw, are bought from a reputable supplier and used by the construction experts properly, be diligent and firm. Because you and your family will be residing there for many years, only quality construction and appropriate use of cement for construction will guarantee longevity.
see also about: hydration cement
Bottom line
A quality cement test examines the strength and quality of the cement used in construction. In addition, these cement tests provide insight into the performance and durability of cement, which is used for a wide range of purposes.
We can conclude that cement tests play an essential role in assessing cement quality and helping homeowners, builders, and workers make an informed choice on the cement quality they would like to use. Make sure to choose the ideal cement quality for making your dream home. So, before starting the construction process, don’t forget to do a cement test!
FAQs
What are the different kinds of cement?
Here are several names of various types of cement used in construction: Sulphates resisting cement Low heat cement High alumina cement Ordinary portland cement (OPC) Blast furnace slag cement Quick setting cement Rapid hardening cement Portland Pozzolana cement (PPC)
What is the volume of cement?
0.034722 cubic metres or 1.226 cubic feet is the volume of a single cement bag. This volume is nearly = 34.5 litres.
What is the pH of water for concrete?
The pH of water is higher than 6 for cement, as per IS 456:2000. When utilising this water for mixing and curing, it must be devoid of harmful levels of organic compounds, oils, alkalis, sugar, acids, salts, and other chemicals that could harm steel or concrete.
What is the ratio of concrete mix?
Four parts crushed rock, two parts sand, and 1 part cement make up the safest cement mixture, or 4:2:1.
What are the five types of concrete?
Five common types of concrete are: Lightweight Concrete High-Performance Concrete Reinforced Concrete High-Strength Concrete Precast Concrete
Got any questions or point of view on our article? We would love to hear from you. Write to our Editor-in-Chief Jhumur Ghosh at jhumur.ghosh1@housing.com