initialy setting time up to 10min. & final setting time upto 10 hours
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.
gypsum increase the setting time of cement.
because when we know the setting time of cement we easily identified that where can we use the cement according to there setting time.
yes, if it is before the initial setting time...
Using a Vicat needle, the ASTM determined time for initial concrete setting is equal to or greater than 45 minutes. They set the final setting time is equal to or greter than 375 minutes.
how the water mixed with cement affects the time of its setting
because when we know the setting time of cement we easily identified that where can we use the cement according to there setting time.
Gypsum is added to cement to decrease the setting time.
It's the time from which cement starts the setting process after water is added.. Usually it is 30 min.. It can be delayed or advanced using chemicals..
retarder increases time to set, accelerator decreases setting time
When cement is mixed with water, it forms slurry which gradually becomes less plastic with the passage of time & finally a hard mass is obtained. In this process, at a certain stage when the cement paste is sufficiently rigid to withstand a definite amount of Pressure, it is said to have set & the time required to reach this stage is termed as "setting time".
False-setting is when cement abnormally and prematurely sets.