Introduction to Extra Rapid Hardening Cement
Time is one of the most important factors in construction projects. Time is directly connected to the cost of the project. The use of ordinary portland cement in the construction required more time for hardening and removal of Formwork.
Whereas the Extra Rapid Hardening cement sets faster and also the formwork can be removed earlier. The construction which is done by using Ordinary Portland cement generally takes 24 hours to set and hardened completely and it requires consistent curing. The OPC cement shuttering removal time is about 14 days.
In some special cases, it is not possible to keep shuttering for 14 days. Some construction required to be completed very fast. For example, Construction of roads and underwater construction, in this case Extra Rapid Hardening cement is used which will set and hardened quickly.
In this article, we will going to learn about the Extra Rapid Hardening cement and it’s properties, Advantages and Disadvantages of Extra Rapid Hardening cement. Extra Rapid hardening cement is basically a modification of the rapid hardening cement.
What is Extra Rapid Hardening Cement?
Extra Rapid hardening cement is a special type of cement which sets very quickly as compared to conventional types of cement. Extra rapid hardening cement is made by proper grinding of Rapid hardening cement with Calcium chloride.
The 3% of calcium chloride is added with Rapid hardening cement which will form Extra Rapid Hardening cement. Rapid hardening cement is also popularly known as High early strength cement. In the case of the Extra rapid hardening cement, a large quantity of heat is evolved during its placing in a very less time.
The care should be taken with the Extra Rapid hardening cement should be used within one month of its manufacturing. This type of cement should not be stored for more than one month otherwise it will lose its properties and does not give desired results.
The Extra rapid hardening cement should be Transported, placed, and compacted at the construction site within 20 minutes of its preparation. The Extra rapid hardening cement is best suitable for the construction and concreting works in cold weather.
If we use Ordinary Portland cement (OPC) for concreting in the cold weather it will lead to the freezing of concrete. The Extra Rapid Hardening cement generates higher heat of hydration due to which it does not freeze even in such an extreme cold climate.
That’s why Engineers recommend using Rapid Hardening cement for construction in the cold weather. The Extra Rapid hardening cement should be stored in a cool place and it should be stacked in a safe and stable manner.
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Properties of Extra Rapid Hardening Cement
The extra rapid hardening cement possesses various properties due to which it is used in the construction
- The calcium chloride is added and grinds properly in the rapid hardening cement which produces extra Rapid Hardening cement.
- A higher percentage of Tricalcium Silicate(C3S) is added in the extra rapid hardening cement which will help to sets quickly.
- The Tricalcium silicate has the property to generate higher heat of hydration which will help it to quickly set.
- The 3 days strength of extra rapid hardening cement is equal to the 7 days strength of OPC cement.
- The Setting Time of Extra Rapid Hardening cement should not be altered by using various types of admixtures.
Uses of Extra Rapid Hardening Cement
Extra rapid hardening cement used in various construction activities which are as follows
- This cement is used in the construction structures in waterlogged areas such as Bridges and dams.
- Extra Rapid Hardening cement is suitable for concreting in cold weather.
- This type of cement is best suitable for the construction of roads where the traffic is not allowed to stop for a longer period.
- It is used where high early strength is required in the construction.
- Extra rapid hardening cement is widely used where the formwork has to be removed within a short period of time.
Advantages of Extra Rapid Hardening Cement
There are many advantages of extra hardening cement which are as follows.
- Extra Rapid Hardening cement sets quickly so it is suitable for concrete in cold weather.
- In the case of this type of cement, we can remove shuttering and formwork earlier as compared to OPC cement. This shuttering and formwork can be used for other work.
- Extra rapid hardening cement is lighter in weight compared to conventional cement.
- Extra Rapid hardening cement is best where early strength is required within a short period of time.
- Extra rapid hardening cement gives higher strength than Rapid Hardening cement.
- This type of cement has good sulphur resistance.
- The curing period of extra rapid hardening cement is less as compared to ordinary Portland cement which makes it Economical.
Disadvantages of Extra Rapid Hardening Cement
There are also some disadvantages of using extra hardening cement which are as follows.
- The cost of Extra rapid hardening cement is comparatively high than other types of cement.
- In the extra rapid hardening cement there may be chances of developing crack due to higher heat of hydration.
- Extra rapid hardening cement is not suitable for the massive concreting work because it generates Higher heat of hydration as compared to other types of cement.
- The storage of the Extra Rapid Hardening cement is to be done with great care otherwise a little moisture will Harden the cement.
- Extra rapid hardening cement cannot be used after one month of its manufacturing.
Applications of Extra Rapid Hardening Cement
There are various applications of extra rapid hardening cement in the Construction Industry which are as follows
- Extra Rapid Hardening cement is used the construction activities in waterlogged areas.
- Extra rapid hardening cement is widely used in the construction of roads where it is not possible to stop the traffic for a longer time, this cement will allow the foot traffic within 4 to 5 hours and vehicles within 8 to 10 hours.
- Extra rapid hardening cement is best suitable for the concreting work in extremely cold climate conditions which will resist the concrete from freezing.
- Extra Rapid Hardening cement can be used for the construction of foundations for heavy machinery and equipment in the factories because machinery required to be installed immediately.
- Extra rapid hardening cement has a property of early strengthening and hardening due to which it is widely used for the repair works of concrete cracks in Dams and roads.
- As this Cement has good sulphur resistance, it can be used to sites where there is a high chance of sulphate attacks.