When tested, cement with the standard consistency allowed the vicat plunger to penetrate to a point 5 to 7 mm from the vicat mould’s base. The steps to determine how much water is needed to make cement paste with a specific consistency are detailed below.
Vicat Devices: The vicat apparatus consists of a frame with a moveable rod that has a cap at one end and any one of the interchangeable attachments listed below at the other end:
- Measurement tool for the first setting time
- Needle for calculating the timing of the final setting
- Plunger used to determine the uniformity of the standards
Needles: Needles Initial Setting Time Needles The needle’s cross section measures 1 mm2. The needle’s tip is flat. Final Needle Setting Time The needle is round and has a 1mm2 cross section. The needle has a metal attachment on it. The needle’s tip extends past the hollowed-out metal attachment’s cutting edge. Plunge for Consistency in Standards It has a projection at the top end that may be inserted into the movable rod and is made of polished brass with a diameter of 10 0.05mm. The bottom is flat.
Adjustable Rod: A graduated scale attached to the frame is moved over by an indicator on a moving rod (certain models have an additional attachment of dashpot, which facilitates lowering of movable rod slowly).
Fourth Graduation: The smallest division of the graduated scale, which has a length of 40mm, is 1mm.
Vicat Mould: only one mold The vicat mold is in the form of a cone frustum with internal dimensions of 60 +/- 0.5 mm at the top, 70 +/- 0.5 mm at the bottom, and 40 +/ 0.5 mm in height. Vicat mold of the split kind An alternative to the single mold is the split type vicat mold. This mold consists of a split ring with a height of 40+/_0.5mm and an internal diameter of 80+/-0.1mm. There is a non-porous base plate available. A proper clamping ring is included with the split mold.
Procedure for Standard Consistency of Cement:
- Maintain a level basis for the vicat equipment (when using vicat apparatus with dashpot, keep the bearing movable rod to its highest position and pin it.) Remove the dashpot’s top screw. Add any acceptable oil of the proper viscosity to the dashpot halfway, then screw the lid on. Plunge the valve a few times.
- Connect the movable rod to the plunger used to determine standard consistency. Plunge the valve a few times.
- Put 400 g of cement in a pan and some water in a beaker that has been weighed.
- With the cement that has had water added, make a paste.
- When adding water to cement, start the stopwatch.
- Place the cement paste into the vicat mold and keep it on a non-porous plate.
- Shake the mold a little bit once it has been fully filled to release any air. Make the paste’s surface level with the top of the molder by sanding it down. The test block is created by creating the cement paste.
- Under the movable rod containing the needle, place the test block sitting on the non-porous plate.
- When using a vicat apparatus with a dashpot, set the mould containing the cement paste and the non-absorbent plate on the base plate of the vicat apparatus. Then, lower the plunger gently until it touches the cement paste’s surface and rapidly release.
- Bring the dash pot’s plunger into touch with the movable bearing rod’s top cap by raising it.
- Remove the pin that is securing the movable bearing rod to the cement paste’s top and quickly release it by pressing the plunger all the way down. After the mold has been filled, this procedure must be carried out right away.
- As the plunger reaches a point 5 to 7 mm from the vicat mould’s bottom, which is read on the scale, prepare trial test specimens using varied water percentages. Expressed as a percentage of the dry cement’s weight, the amount of water needed.
