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".
The factors that affect initial setting time of cement are temperture, humidity and the fineness of the cement.
vicats apparatus is used for initial setting time of cement.
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.
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.
Dry cement in bags is stored in a dry place protected from the weather. For large construction sites this is usually a secure storage area. If you are talking about mixed cement (wet) or concrete, then it is not stored on a construction site. It is mixed off-site and carried to the site in large "cement mixer" trucks. The it is placed (or poured) prior to the initial setting time specified by the concrete manufacturer.
the rise of price of cement
yes, if it is before the initial setting time...
Factors affecting the location of cement industries include proximity to raw materials, a strong labor force, good roads and transportation. Many cement plants are built near limestone quarries or coal mines.
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.
does this cement satisfy ASTM standard requirements for normal consistency
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..
vicats apparatus is used for initial setting time of cement.
Factors are:Availability of raw materialSufficient waterLabourLandPowerCapital(Money)TransportMarket
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.
False-setting is when cement abnormally and prematurely sets.
Compressive Strength Workability Durability Maximum Size of Aggregate Water/Cement Ratio Quality Control
gypsum increase the setting time of cement.