Vicat Apparatus is a device used to determine the consistency and setting time of cement. Consistency and setting time of cement are significant degrees of consideration for any cement water paste. As these helps in preparing a proper paste of cement which meets all the standard specifications. Vicat apparatus consists of a metallic frame, graduated scale with index, sliding probe of 300g, consistency plunger of 10mm, initial setting time needle of 1mm, an annular needle for final setting time calculation and non-porous plate, like glass base plate or stainless plate.
We also conduct a test of knowing the expansions or volume changes in cement, i.e., Soundness Test Of Cement by Le-Chatelier Apparatus. But before this, we also come to know the Sieve Test Procedure To Check Fineness Of Cement. As the fineness and soundness are very crucial for sustenance or otherwise the structure will not bear the heavy loads. A standard representation of the Vicat apparatus with standard dimension is shown below.
To calculate the initial and final setting time of cement by using Vicat apparatus.
- Cement in the presence of water indulges in the process of hydration. This hydration process is imperative in context to stiffening of cement. During the process of cement hydration form, a compound of aluminium silicate and the process continue until the cement completely hardens and takes the shape of the mould.
- The initial setting of the cement is time duration time at which the cement start to stiffen to a defined consistency and loses its plasticity, Whereas the final setting time cement is the time duration at which the cement gets harden enough and takes the form of the mould.
- The initial setting of cement is lies in between 30-60 minute, on the other hand, the final setting time lies in between 9-10 hours.
Initial Setting Time
Final Setting Time
|S.NO.||Type Of Cement||Referenced Indian Stanadard||Initial Setting Time, mints (min.||Final Setting Time, mints (max.)|
Initial setting time = t2 - t1 final setting time= t3 - t1 where, t1= time at which water is first added to the cement. t2= time at which needle fails to penetrate the 5mm to 7mm mark from bottom of the mould. t3= time at which needle makes an impression but fail to do so.
- The gauging time period should not be less than 3 minutes and not exceeds to 5 minutes.
- Handle the apparatus of checking the initial and final setting of cement with care.
- The position of the mould should be changed after every penetration so as avoid the penetration at the same place.
- The reading should take properly and carefully.
Vicat Apparatus Uses
- The Vicat apparatus is used to determine the consistency of cement under a defined water to cement ratio.
- It helps in calculating the initial setting time of the cement so that the time period at which the cement paste losses it plasticity can be determined. It helps in determining the consistency of cement during its transportation to far off places.
- It also helps in determining the significant time period for complete hardening of cement.