Setting Time of Water

                  Cement when mixed with water forms a paste which gradually becomes less plastic and finally hard mass is obtained.In this process setting stage is reached by the cement paste is sufficient visit to withstand a definite amount of  amount of pressure.A time to reach this stage is initial setting.
This Setting is divided in two types

1.  Initial Setting Time
2. Final Setting Time

Initial Setting Time:

                     The Time in which cement paste losses its plasticity is called Initial Setting Time.

Final Setting Time :

                      The time taken to reach take stage ,when the paste becomes hardness is known as Final Setting Time.

                      For O.B.C initial setting time should not be less than 30 minutes and final setting time should be 60 minutes.

                       Out of the 4 major compounds C3A reacts quickly with water to produce  jelly like compounds which start solidifies setting action is delay by adding gypsum at the grinding stage.Gypsum reacts with water   C3A to form tetra calcium Aluminiate hydrate and the setting time retarded to desired time.