What Is Final Setting Time Of Cement?

What Is Final Setting Time Of Cement
2 The Setting Time – The setting time of cement includes the initial setting time and the final setting time, The initial time refers to the time that cement turns into paste by mixing with water and begins to lose its plasticity. And the time that cement completely loses its plasticity by mixing with water and begins to have a certain structural strength is known as the final setting time.

  1. The national standards prescribe that the initial setting time of Portland cement should not be earlier than 45 min and the final setting time should not be later than 6.5 h.
  2. All the products off-grade at the initial setting time are spoiled products and those unqualified at the final setting time are sub-quality products.

The setting time of cement is measured by time determinator. The sample is the standard cement paste of which the temperature is 20 °C ± 3 °C and humidity is more than 90%. Various mineral components of the cement clinker are different in the water consumption of their normal consistency.

  1. The finer the cement is ground, the more water the normal consistency will need.
  2. The normal consistency of Portland cement is within 24% ~ 30%.
  3. The setting time of cement is very important in the construction projects.
  4. The initial setting time should not be too fast in order to ensure that there is enough time to complete every process, such as casting, before the initial setting time; and the final setting time should not be too late in order to enable the cement to complete its setting and hardening as soon as possible after pouring and tamping to make the next process occur earlier.

Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781845699550500049

What are the initial and final time of cement?

Importance of Initial And Final Setting Time – After mixing cement with water, placing the cement paste in a position requires time. Initial setting time plays an essential role in the strength of cement or concrete. In the case of ordinary Portland cement, the cement paste or concrete must be placed before crossing the initial setting time.i.e., 30 minutes and should not be disturbed until it meets the Final setting time, i.e., 600 minutes,

  1. The cement should not be set too fast and not be too slow. If it set rapidly, it doesn’t offer sufficient time for transportation and placing of the concrete. While if it is set too late, it can slow down the work and might be postponed due to less strength at the desired time.
  2. The setting of cement should not be compared with hardening. It is a mechanical strength gained after a specific time interval to resist the penetration of a special attachment dropped into it.
  3. Initial setting time is essential to transport, placing and compaction of concrete.
  4. Initial setting time is necessary to delay the hydration process and hardening.
  5. Final setting time helps to remove shuttering or formwork safely.
  6. Cement completed its chemical reaction with water till the final setting time.

What is setting time cement?

Conclusion – Initial and final setting time of cement are very important properties of cement, which are responsible for the quality of concrete and mortar. Hence it is advisable to check the initial setting time and final setting time of cement before you use it for the construction work.

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What is the final setting time of cement Mcq?

Final setting time should be less than 375 minutes.375 minutes is equivalent to 10.25 hours.

What is initial setting cement?

Test Procedure : –

A cement paste is prepared by adding water 0.85P% by weight of cement. The time of mixing should not be less than 3 minutes and should not be more than 5 minutes. Now the paste is filled in the Vicat mould and the top is levelled off. The mould is now placed under the square needle with annular collar and is brought down touch the surface of the paste. Now the square needle with annular collar is suddenly released and allowed to make on impression on the cement paste by its own weight. The impression made by this square needle with annular collar is observed. The whole experiment is repeated with incremental time intervals until such a time when the square needle makes an impression on the paste while the annular collar fails to do so. The time elapsed between the moments when water is added to the cement to the time when the square needle makes an impression on the paste while the annular collar fails to do so is known as the Final Setting Time of the cement. The final setting time of cement should not be more than 600 minutes for Ordinary Portland Cement.

Also Read : Workability of Concrete & Factors Affecting It

Why do we set the 30 minute initial time of cement?

This is the time at which the hardening of the cement starts and the only time available for mixing the paste and placing it in position. if this time less then 30 min then can’t molded in any shape in many situations.

What is initial setting?

2 The Setting Time – The setting time of cement includes the initial setting time and the final setting time. The initial time refers to the time that cement turns into paste by mixing with water and begins to lose its plasticity. And the time that cement completely loses its plasticity by mixing with water and begins to have a certain structural strength is known as the final setting time.

  • The national standards prescribe that the initial setting time of Portland cement should not be earlier than 45 min and the final setting time should not be later than 6.5 h.
  • All the products off-grade at the initial setting time are spoiled products and those unqualified at the final setting time are sub-quality products.

The setting time of cement is measured by time determinator. The sample is the standard cement paste of which the temperature is 20 °C ± 3 °C and humidity is more than 90%. Various mineral components of the cement clinker are different in the water consumption of their normal consistency.

The finer the cement is ground, the more water the normal consistency will need. The normal consistency of Portland cement is within 24% ~ 30%. The setting time of cement is very important in the construction projects. The initial setting time should not be too fast in order to ensure that there is enough time to complete every process, such as casting, before the initial setting time; and the final setting time should not be too late in order to enable the cement to complete its setting and hardening as soon as possible after pouring and tamping to make the next process occur earlier.

Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781845699550500049

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What is the setting time of OPC?

Initial setting time should not be less than 30 minutes and final setting time should not be greater than 600 minutes as per IS 12269.

What is called setting of cement?

What is Concrete Scaling/Flaking and How do I Prevent It? Scaling is a fairly, It refers to the flaking or peeling of a hardened concrete surface, typically due to repeated exposure to freeze/thaw cycles. Scaling occurs when parts of the concrete surface start to flake or chip away, eventually exposing the coarse aggregate below.

  1. While light scaling does not expose the coarse aggregate particles below, very severe scaling (the most extreme version) is marked by surface mortar erosion, coarse aggregate loss, and surface loss that exceeds 20 mm.
  2. In addition to harsh freeze-thaw cycles, concrete that is not properly air-entrained will result in scaling as well.

Deicing chemicals can also accelerate and worsen scaling. Poor finishing practices are also a known culprit that can lead to scaling in the future. Scaling typically starts in one area of the concrete, but if left untreated, it can expand to others.

What is setting time test?

FAQs – What is initial setting time of cement? The initial setting time of concrete is the time when cement paste starts hardening after adding water. It is the time period between the addition of water to cement till the time at 1 mm square section needle fails to penetrate the cement paste, placed in the Vicat’s mold 5mm to 7mm from the bottom of the mold.

What is final setting time of cement? Final setting time is that time period between the time water is added to cement and the time at which 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression. What is the need for determining initial and final setting time of cement? Initial setting time is the time when the paste starts losing its plasticity.

The test is important for transportation, placing and compaction of cement concrete. Initial setting time duration is also required to delay the process of hydration or hardening. Final setting time is the time when the paste completely loses its plasticity.It is the time taken for the cement paste or cement concrete to harden sufficiently and attain the shape of the mould in which it is cast.

Which needle is used for final setting time?

🕑 Reading time: 1 minute Final setting time is that time period between the time water is added to cement and the time at which 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression. This is test is required to understand the rate of gain of strength of cement with respect to time.

What is the importance of slump test?

Why do a slump test? – A concrete slump test is a way of finding out the consistency of different concretes. The benefits of performing a slump test are that it shows the workability of the concrete and the ease with which it flows, as well as being an indicator of an improperly mixed batch. What Is Final Setting Time Of Cement Checkout our guide on Concrete Slump Tests – a detailed guide on how to perform your won slump test. When working on a big project with several loads of concrete, a slump test can help to ensure that each one is uniform. So, knowing what the slump of your concrete is and what class it falls into is really important for getting your concrete mix ready for the job.

What is the difference between initial set and final set?

Technical Aspects of Concrete Setting Times: –

  • It is necessary that cement set neither too rapidly nor too slowly. In the first case, there may be insufficient time to transport and place the concrete before it becomes too rigid. In the second case too long a setting period tends to slow up the work unduly, also it might postpone the actual usage of the structure because of adequate strength at the desired age.
  • The setting should not be baffled with hardening, which refers to the gain in mechanical strength after a certain degree of resistivity to the penetration of a special attachment pressed into it.
  • Setting time is the time needed for the stiffening of cement paste to a defined consistency.
  • Indirectly related to the initial chemical reaction of cement with water to create an aluminium-silicate compound.
  • The initial setting time is the time when the paste begins losing its plasticity.
  • The initial setting time test is crucial for the transportation, placing, and compaction of cement concrete.
  • An initial setting time period is needed to delay the process of hydration or hardening.
  • The final setting time is the time when the paste entirely loses its plasticity.
  • It is the time taken for the cement paste or cement concrete to harden sufficiently and achieve the shape of the mould in which it is cast.
  • Determination of final setting time period assists safe removal of scaffolding or form.
  • During this period of time, the essential chemical reaction of cement with water is almost completed.
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What is the difference between OPC and PPC cement?

2.Portland Pozzolana Cement (PPC): – PPC cement is generally used for plastering, brick masonry and waterproofing works. PPC has a lower heat of hydration and it is prone to fewer cracks compared to OPC. PPC has lower strength than OPC but PPC provides better workability and finishing than OPC. PPC provides greater resistance to chemicals. What Is Final Setting Time Of Cement

What is fineness of cement?

This answer was edited. The fineness of cement is a measure of the size of particles of cement and is expressed in terms of the specific surface area of cement. The fineness of cement is measured as the % weight retained on a 90µm IS sieve over the total weight of the sample.

  1. In the laboratory, the fineness of cement is tested by sieving and by the determination of a specific surface.
  2. For ordinary cement, the weight of residue left on the sieve shall not exceed 10%.
  3. The fineness of cement is the significant factor affecting the rate of hydration, rate of gain of strength, setting time, and rate of evolution of heat.

The rate of strength development increases with fineness. Since the specific surface area is inversely proportional to the size of the particle, the surface area is more for finer cement than for a coarser cement. Therefore, the finer the cement, the higher the surface area for hydration and hence faster the development of strength. What Is Final Setting Time Of Cement Smaller cement particles react much quicker than the larger particles. A cement particle with a diameter of 1 µm will react entirely in 1 day, whereas the particle with a diameter of 10µm takes about 1 month. It is found that the particle size fraction below 3 microns affects one day’s strength and 3 to 25-micron fraction influence the 28 days’ strength.

  1. Setting time decreases with an increase in the fineness of the cement.
  2. Too much smaller particles in cement results in quick setting, thereby leaving no time for mixing, handling, and placing.
  3. Also, such cement is susceptible to air set and early deterioration.
  4. To increase the setting time of cement, it must be manufactured in a different range of particle sizes.

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What is the initial time of cement?

The setting of cement starts within 5 minutes after addition of water and it becomes hard like stone in less than 30 minutes or so.