Which is used to increase the initial setting setting time of cement?

Accelerators have been designed to significantly boost the early setting times and increase the early age strengths of concrete.

What is the initial setting time of cement concrete?

30 minutes
The time elapsed between the moments when water is added to the cement to the time when the square needle penetrates a depth of 33 to 35 mm from the top of the mould is known as the Initial Setting Time of that cement. The initial Setting Time should not be less than 30 minutes for Ordinary Portland Cement.

Which of the following admixture decreases the setting time of cement?

Retarding admixtures are used to slow the rate of setting of concrete. By slowing the initial setting time, the concrete mixture can stay in its fresh mix state longer before it gets to its hardened form. Use of retarders is beneficial for: Complex concrete placement or grouting.

How is admixture used in concrete?

Admixtures are used in concrete to enhance the performance of the mix in various ways. Generally added before or during the mixing process, admixtures can increase the strength the mix, accelerate or slow down the curing process among other benefits.

What is plasticizer admixture?

The combination of organic substances or combinations of organic and inorganic substances which cause reduction in water content for a given workability or give a higher workability at the same water content are known or termed as plasticizer admixtures.

What is initial and final time of cement?

Initial Setting Time of Cement = 7:45 am – 7:00 am = 45 min. Final setting Time of Cement = 12:00 pm – 7:00 am = 5 hr = 300 min.

How do you find the initial and final setting time of concrete?

Record the period elapsed between the time of adding water to the cement to the time when needle fails to pierce the mould by 5 + 0.5mm as the initial setting time. Final Setting Time • Replace the needle of the vicat apparatus by the needle with an annular ring • Lower the needle and quickly release.