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Today i will be talking about the importance of setting time of cement. This is important for you as a foreman because without the knowledge of setting time of cement, a lot of mistakes could be made that would result to total waste of materials (Concrete, Mortar) on site.
On This post, you’ll understand the meaning of Initial setting time Of Cement
You will understand the different types of setting time of cement.
What is Initial setting time Of Cement?
The Initial Setting Time Of Cement starts right from when water is added to cement to the point where it starts to lose its plasticity.
According to According to BS 6699:1992, it should not be less than 15 mins for OPC (Ordinary Portland cement)
What is The Final Setting time Of Cement?
The final setting time of cement is the time at which the cement has totally lost its plasticity and hard enough to form the shape of the mold on which it has been cast.
Or
The final setting time of cement is the time it takes for the cement to become completely solidified after hydration has taken place.
The duration of this final setting time is predicted to be 375 – 600 minutes according to Indian Standard (IS 4031:1988
Why is Initial Setting Time Is Important On Site?
1. Importance Of setting time In Mixing Of Cement
Setting time should be such enough that cement an be easily mixed with other constituents (aggregate,sand,admixtures) easily.
Also Read: Steps In Buying Plots Of Land In Nigeria
2. Importance Of setting time In Transportation of concrete
Setting time plays an important role in a situation where concrete has to be transported via transit mixers to a far site
3. Importance Of setting time In Placing Of Concrete
Setting time should be such enough to be that concrete can be placed easily without effecting its workability
In case of concreting in heavy mass structures or high rise buildings setting time plays an important role
4. Importance Of setting time In Compacting Of Concrete
Concrete placed should be in liquid state enough to be compacted easily by vibrators leaving no void or honeycombing.
5. Importance Of setting time In Finishing
Setting time should such enough that outer surface of structure can be given desired finishing.
Also Read: Meaning Of Cement Concrete
6. Importance Of setting time In Removal of form work
Setting time should not be more than desired limit as removal of form-work plays an important role in rapid construction of high rise buildings
7. Importance Of setting time In Shrinkage
If initial setting time is increased then afterwards setting rate increases rapidly thus shrinkage in stricture is more which leads formation of cracks.
How Can setting Time Of Cement Be Manipulated?
Setting time Of Concrete can manipulated by usage of retarders such as calcium ligno-sulphates,carbohydrates derivatives
The maximum limit to which initial setting setting time could be increased is by 72 hrs
