Initial set indicates the approximate time at which the paste begins to stiffen considerably. Final set roughly indicates the time at which the cement paste has hardened and can support some load. Initial setting time indicates the beginning of the setting process when the cement paste starts losing its plasticity. Final setting time is the time elapsed between the moment water is added to the cement and the time when the cement completely lost its plasticity and can resist certain definite pressure.
It is the state from which it enters into amorphous state from plastic state. At setting state if we remove suppose it holds its position for a while but i nternal crack and deformation start to surface because of absence of strength.
Hardening or stiffening: It happens after setting state. Ask Question. Welcome back. Continue with Google Continue with email. Write a short note on : Setting and hardening of cement. Please log in to add an answer.
Continue reading It means the concrete after setting and hardening. The difference between ordinary Portland cement and composite Portland cement are the ingredients used to make the cement. Composite Portland cement has Portland cement mixed with other materials. Cement when mixed with sufficient quantity of water,the compounds present in cement reacts with water to form a cementitious crystalline structure that adheres to the sand and aggregates.
This helps in binding the mass together and increases its strength till it becomes very hard. This is called hardening of cement.
An arbitrary division has been made for the setting time of cement as initial setting time and final setting time. It is difficult to draw a rigid line between these two arbitrary divisions.
For convenience,initial setting time is regarded as the time elapsed between the moment that the water is added to the cement,to the time that the paste starts losing its plasticity. The final setting time is the time elapsed between the moment that the water is added to the cement ,and the time when the paste has completely lost its plasticity and has attained sufficient firmness to resist certain definite pressure.
Psc is always first choice because psc cement gives more strength than opc and also psc cement setting time is slower not that much it will give same strength in 28 days Because of slower setting cracks will not appear or there is very less chance to appear cracks and it will requires lesser curing than opc.. False-setting is when cement abnormally and prematurely sets. Setting of cement involve chemical changes. The initial setting time for cement is 30 mins. The size of the rocks.
No, you cannot reuse the cement after it has crossed the setting time. The factors that affect initial setting time of cement are temperture, humidity and the fineness of the cement. Cement is just the powder used to make mortar and concrete. Mortar has sand in it. The initial setting time of cement is 30 minutesThe final setting time of the cement is 10 hours. The initial and final setting time of the cement can be found by using the Vicat's apparatus. The difference between corrugated asbestos roofing and flat asbestos cement sheet is the form in which it was cast and, perhaps, the thickness of the finished product.
Asbestos was merely an additive to cement. Both products are basically cement with a fiber strengthener that happens to be asbestos. Acrylic or epoxy based paint for cement surfaces is called cement paint. Cement that includes acrylic or epoxy to coat surfaces is called cement based paint. Masonry cement is similar to OPC but has a plasticiser added to the cement powder.
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