What is Quick setting cement?
Quick setting concrete Also known as quick setting cement, quick setting cement is a special variation of Portland cement. It is prepared from gypsum, aluminum sulfate and Portland clinker in a predetermined ratio. The high setting rate of cement is due to the presence of aluminum sulfate which accelerates hydration. The usual setting time for quick setting cement is five minutes. This type of cement provides high strength and durability to the structure. Therefore, it is an ideal choice for buildings exposed to a lot of moisture. In addition, cement with a low dry shrinkage ratio and fewer voids makes the building very resistant to cracking.
How to Use Quick Setting Cement?
Quick-setting cement is an affordable solution for all structures that need quick repair. However, certain rules must be observed when using it. Here are the steps to follow when working with this cement:
Read the instructions for use available with the quick-setting cement and follow the ratios available on it for mixing. This will help avoid unnecessary clumping
Always mix concrete near the job site as concrete tends to harden very quickly. Also, mix cement in small quantities to avoid the risk of premature hardening
Try not to mix Quick setting cement for more than 10 minutes
Be very cautious when working with the cement in temperatures less than or equal to four degrees as it can lead to freezing
Uses of Quick Setting Cement
It is used in under water construction.
It is also used in rainy & cold weather conditions.
Where quick strength is needed in short span of time.
Used higher temperature where water evaporates easily.
Used for anchoring or rock bolt mining and tunneling
Used for fixing concrete steps.
For the anchorage of Rock Bolt in Tunnel & all works underground, quick setting cement is required.
Advantages of Quick Setting Cement
It has less setting time but its ultimate strength is the same as OPC
These cement types generally have high resistance to water
Less water is required during the hydration process
It can be used for repairs without disturbing the structures
Disadvantages of Quick Setting Cement
It is weak to sulphate attack and durability is compromised due to the high content of aluminum sulphate
After the water is added, mixing and placing have to be done very fast or the concrete will set before use and be wasted
It is not common and might not be available in some places
It is expensive
When using quick setting cement if the heat is not dissipated properly, it may have cracks after setting
Phenomenon of Quick setting cement:
Usually, when water is added into cement hydration, a chemical reaction occurs which hardens the cement, while the initial setting time is 30 minutes and the final setting time is 10hrs. In this cement, the setting time of cement decreases and the hardening of cement increases. The cement clinker is ground with aluminum sulfate, which accelerates the setting time of the cement, while aluminum sulfate is used as an accelerating admixture within a dose range from 1% to 3% by weight of cement clinker.
The mechanism action of aluminum sulfate increases the rate of hydration of the triacalcium silicate (C3S) and triacalcium aluminate (C3A) phases of cement, leading to pre-heat evolution and strength development. It acts as a catalyst in the hydration of tricalcium silicate (C3S) and triacalcium aluminate (C3A). Concrete samples with different percentages of aluminum sulfate were tested for compressive strength, tensile strength and flexural strength. The results obtained compared with the normal results of the concrete mix M-20 showed that there was a maximum increase in tensile strength and separation strength when installing fast setting cement concrete at 3 days of age and 7 days of age. However, after 28 days, there was no significant increase in compressive strength, tensile strength and flexural strength.
Why Is Quick-Setting Cement a Good Building Material?
Fast setting cement has many advantages that make it a good building and flooring material. Here are some reasons why:
Thanks to its properties, it can be used to perform waterproofing work in large spaces such as tunnels and basements.
It can even be applied underwater without affecting its curing.
It can be used both indoors and in areas affected by weather conditions.
It has many uses and is very versatile.