Initial and Final Setting Time of Cement Test
The setting time of cement is an important characteristic that determines its performance and application.
The setting time refers to the time it takes for cement to harden and become stable after it has been mixed with water.
This process involves a series of chemical reactions that lead to the formation of a hardened mass.
To measure the setting time of cement, two tests are commonly used – the initial and final setting time tests.
These tests are critical in ensuring that the cement is used appropriately and that it performs as expected in various applications.
In this context, understanding the significance and methods of conducting initial and final setting time tests is crucial for anyone involved in the production, distribution, or use of cement.
Initial Setting Time
The initial setting time of cement is the time taken by the cement paste to set and harden to a point where it can no longer be disturbed by any external force.
This is typically measured using the Vicat apparatus, and the standard requirement is that the initial setting time should not be less than 30 minutes for ordinary Portland cement.
Final Setting Time
The final setting time of cement is the time taken by the cement paste to reach a state of complete hardening and development of strength.
This is also measured using the Vicat apparatus, and the standard requirement is that the final setting time should not be more than 10 hours for ordinary Portland cement.
Read More: What Is Cement And History Of Cement
Tests On Cement
The following tests are conducted on cement in the laboratory are as follows:
- Fineness Test of Cement
- Consistency Test of Cement
- Setting Time Test of Cement
- Soundness Test of Cement
- The heat of Hydration Test
- Speicific Gravity Test of Cement
- Tensile Strength Test
- Chemical Composition Test
Importance of initial and final setting time of cement
- It is required that cement does not lose its plasticity too early or too late. If cement is set too early, there is insufficient time for transportation and place of concrete.
- If cement is set too late then there is a delay in construction work. Also, concrete will not get sufficient strength early and the formwork removal process delayed.
- The proper setting time is required for the stiffening of cement paste to a defined consistency.
- It is indirectly related to the chemical reaction of cement with water to form an aluminum-silicate compound.
- Initial setting time is an important time to know for concrete transportation, placing, and curing.
- Initial setting time is also utilized to delay the process of hydration or hardening.
- The final setting time is utilized for the safe removal of scaffolding or form.
Factors Affecting Setting Time of Cement
The initial and final setting times of cement are important properties that determine its suitability for various construction applications.
The initial setting time refers to the time taken by the cement paste to lose its plasticity and become rigid enough to resist certain loads without any appreciable indentation.
This time is important for processes such as handling, transportation, and placement of concrete. If the initial setting time is too short, the concrete may not be workable, and if it is too long, the concrete may start setting before it is placed, causing difficulty in finishing.
The final setting time is the time taken by the cement paste to harden and attain its ultimate strength.
This is important for ensuring that the concrete attains its full strength and durability, and can resist external loads and environmental factors over a long period of time.
If the final setting time is too short, the concrete may not attain its full strength, while if it is too long, the setting may be delayed, leading to prolonged construction times and increased costs.
In summary, the initial and final setting times of cement are crucial parameters that impact the workability, strength, and durability of concrete.
Therefore, it is important to ensure that these parameters are within the desired range to achieve the best results in construction projects.
Procedure For Initial and Final Setting Time of Cement
1. Balance – The permissible variation at a load of 1000 g shall be ± 1.0 g.
2. Vicat Apparatus – Vicat apparatus should confirm to IS: 5513-1976.
3. Stop Watch
4. Gauging or Mixing Trowel
5. Glass Plate
6. Enamel tray
Preparation of Test
1. Consistency of cement shall be tested before conducting a test to find out % of the water required by the weight of cement as normal consistency of cement (P).
2. Take about 400 gm of cement and add water about 0.85x P (P is % water required for normal consistency of cement)
3. Mix water with cement quickly in a short time about 3 min to 5 min. Start the stopwatch at the instance when water is added to the cement. Record this time (T1).
4. Now, fill this prepared cement paste in a Vicat apparatus mould having a diameter of 80 mm and a height of 50 mm resting on a non–porous glass plate. Properly fill and smooth off the top surface of the mould and level it.
For Initial Setting Time
1. For determining the initial setting time of cement, place this mould filled with cement paste below the Vicat apparatus and fit the needle used for testing the initial setting time.
2. Lower the bottom of the needle such that it touches the top of cement paste filled in mould.
3. Remove the locking pin from the top and quickly release the needle, allowing it to penetrate into the cement paste.
4. At the beginning, the needle penetrates and touches the bottom of mould. Repeat this process, like quickly releasing the needle after every 2 minutes till the needle fails to penetrate the cement paste for about 5 mm measured from the bottom of the mould.
5. Note Time (T2) when the needle fails to penetrate 5 mm from the bottom of the mould.
Fitial Setting Time
1. For determining the final setting time of cement replace the needle with another needle having an angular ring attachment.
2. Now, slightly release this needle on the surface of the cement paste and observe whether it is making an impression of the ring on the surface or not. Not the time when need fails to make an impression on the surface of cement paste. (T2)
Calculation of Initial and Final Time:
Initial setting time of cement = Time when needle fails to penetrate 5 m from the bottom of mould.(T2) – The time when added to cement (T1)
Final setting time of cement = Time when angular need ring impression stop on cement paste (T3) – Time when water added to cement (T1)
Suppose, Consistency of cement (P) = 30% and Weight of cement = 400 kg
Water to be added in cement = (0.85 x P ) x 400 = (0.85 x 30%) x 400 = 102 ml
The time when water added to cement = 7:00 am
Time, when needle fails to penetrate less than 5 mm from the bottom of mould = 7:45, am
Initial Setting Time of Cement = 7:45 am – 7:00 am = 45 min.
Time When angular ring needle fails to make impression on the surface of cement paste = 12:00 pm
Final setting Time of Cement = 12:00 pm – 7:00 am = 5 hr = 300 min.
Standard Setting Times for Various Cement
There are various types of cement used in the construction industry. Depending on the types of cement and admixture used in the manufacturing of cement initial setting time and final setting time are differs for cement. The standard-setting time for different types of cement is given below.
|Name of Cement||Ref. IS Code||Initial Setting Time(min)||Final Setting Time(Max)|
|OPC (33)||IS: 269||30||600|
|OPC (43)||IS: 8112||30||600|
|OPC (53)||IS: 12269||30||600|
|High Alumina||IS: 6452||30||600|
|Super Sulphate||IS: 6909||30||600|
|Low Heat||IS: 12600||60||600|
|Masonry Cement||IS: 3466||90||1440|
|IRS – T -40||Railway||60||600|
What is the Flakiness and Elongation Index Test?
The Flakiness and Elongation Index Test is a test conducted on coarse aggregates to determine their shape characteristics. The test involves measuring the percentage of particles in a sample that are either flat or elongated, which can affect the performance of the aggregate in concrete.
What is the Elongation Index?
The Elongation Index is the percentage of particles in a coarse aggregate sample that have a length greater than one and a half times their width. These particles are considered to be elongated, and can cause problems in concrete by reducing the workability and increasing the amount of voids in the mix.
Who can perform the Flakiness and Elongation Index Test?
The Flakiness and Elongation Index Test can be performed by trained technicians or engineers who are familiar with the equipment and procedures involved. The test is typically conducted in a laboratory setting.
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