This test is needed to assess the initial setting time frame of cement, and to comprehend the time-frame cement takes for initial setting among the blending and shifting and placing of concrete.
Vicat apparatus, needle for initial setting time, stop watch.
We have to 400 gm of cement and put it in a steel pan. Then mould it and create a tidy cement paste by putting 0.85 times the water needed to result into a paste of regular constancy by the preceding test. Keep the stopwatch on at the exact moment when the water is incorporated to the cement. Now put the vicat mould/cast on a non absorbent plate and fill up the cement paste in it. After entirely filling up the mould, we have to shake it gently to discharge the air. Even off the face of the paste and make it even and in level with the crest of the mould.
Now put the test block and the non absorbent plate below the rod having the needle having 1sq.mm.cross section. Lower the needle quietly until it is in touch with the facade of the test block and speedily discharge permitting it to enter through in to the test block.(When vicat apparatus with dash pot is utilized, put the mould filled up with cement paste and the non porous plate on the bottom of the vicat apparatus . Then rise in the starting of the needle will entirely penetrate through the block. Reiterate the method again and again until the needle falls short to penetrate through the block for 5+-0.5mm measured from the base of the mould/cast. The time period spent between the time when water is blended to the cement and the time period at which the needle does not succeed to penetrate through the test block by 5+-0.5mm is known initial testing time.
The initial setting time of the given sample of cement=……………..min
OBSERVATIONS AND CALCULATIONS
Weight of cement taken (g) = _________
Quantity of water incorporated to the cement = 0.85 X Quantity of water required for standard consistency = _______
|SL. NO.||TIME (min)
(measured from the instant of adding water to cement)
|DEPTH OF PENETRATION