Vicat apparatus

Vicat apparatus (Vicat apparatus), alias: cement consistency meter, cement consistency setting time tester It is a testing instrument for cement and concrete industries. It is mainly used to detect the standard consistency water demand and setting time of cement paste.
Standard French Vicat

The test rod for standard consistency determination [see lc] has an effective length of 50 mm ± 1 mm and is made of a cylindrical corrosion-resistant metal with a diameter of φ10 mm ± 0.05 mm. When measuring the setting time, remove the test rod and replace it with a test needle [see Figure 1d), e]. The test needle is made of steel, the effective length of the initial setting needle is 50mm ± 1mm, the final setting needle is 30mm ± 1mm, and the diameter is φ1.13mm ± 0.05mm. The total mass of the sliding part is 300g ± 1g. The surface of the sliding rod connected with the test rod and the test needle should be smooth, can fall freely by gravity, and should not be tight and agitated.
The trial mold (see Figure la) for cement paste shall be made of corrosion-resistant metal with sufficient hardness. The test mold is a truncated cone with a depth of 40mm ± 0.2mm, a top inner diameter of φ65mm ± 0.5mm, and a bottom inner diameter of φ75mm ± 0.5mm. Each trial mold should be equipped with a flat glass bottom plate larger than the trial mold and with a thickness ≥ 2.5 mm.

Test Methods
Standard method
I Determination of water consumption for standard consistency (standard method) [1]
1. Must be done before the test
a) The metal bar of the Vicat meter can slide freely;
b) Adjust the pointer to zero when the test rod touches the glass plate;
c) The mixer is operating normally.
2. Mixing of cement paste
Mix with a cement paste mixer. The mixing pot and blades are first wiped with a damp cloth. Pour the mixing water into the mixing pot, then carefully add the weighed 500g cement to the water within 5s to 10s to prevent water and cement from splashing; When mixing, first put the pot on the pot base of the mixer, raise it to the mixing position, start the mixer, mix at low speed for 120s, stop for 15s, at the same time scrape the blade and the cement slurry on the wall of the pot into the pot, then stop at high speed for 120s.
3. Measurement procedure of water consumption of standard consistency
After mixing, immediately put the mixed cement paste into the test mold that has been placed on the glass bottom plate, insert it with a knife, gently vibrate several times, scrape off the excess paste; Move the bottom lever to the Vicat instrument and center it under the test rod. Lower the test rod until it contacts the surface of the cement paste. After tightening the screw for 1s to 2s, suddenly relax and let the test rod sink freely vertically In cement paste. Record the distance between the test rod and the bottom plate when the test rod stops sinking or releases the test rod for 30s. After lifting the test rod, wipe it off immediately; the entire operation should be completed within 1.5min after stirring. The cement paste with the test rod sinking in the paste and 6mm ± 1mm ​​from the bottom plate is used as the standard consistency paste. The mixing water volume is the standard consistency water consumption (P) of the cement, calculated as a percentage of the cement mass.

II Determination of setting time
1 Preparation before measurement: When the test needle of the setting time measuring instrument is adjusted to contact the glass plate, the pointer is aligned with the zero point.
2 Preparation of the test piece: The standard consistency clean water is used to make the standard consistency clean pulp filled with the test mold at a time, shake it for several times, and then put it in the moisture curing box immediately. Record the time when all the cement is added to the water as the starting time of the setting time.
3 Determination of initial setting time: The test piece is cured in a moisture curing box until 30 minutes after adding water for the first measurement. During the measurement, remove the test mold from the moisture curing box and place it under the test needle to reduce the contact between the test needle and the surface of the cement paste. After tightening the screws for 1s ~ 2s, suddenly relax, the test needle sinks into the cement paste vertically and freely. Observe the reading of the pointer when the test needle stops sinking or the test needle is released for 30 seconds. When the test needle sinks to 4mm ± 1mm ​​from the bottom plate, the cement reaches the initial setting state; the time from when all the cement is added to the water to the initial setting state is the initial setting time of the cement, expressed as “min”.
4 Determination of final setting time: In order to accurately observe the condition of the test needle sinking, a ring attachment is installed on the final setting needle. Immediately after the measurement of the initial setting time, the test mold and the slurry are removed from the glass plate in a translational manner, turned 180 degrees, the large end of the diameter is upward, the small end is placed on the glass plate, and then placed in the moisture curing box Continue to maintain, and measure every 15min when the final setting time is approaching. When the test needle sinks into the test body 0.5mm, that is, when the ring attachment can not leave traces on the test body, the cement reaches the final setting state, and all the cement The time from adding water to the final setting state is the final setting time of cement, expressed as “min”.
5 It should be noted during the measurement that the metal column should be gently supported during the initial measurement operation to make it drop slowly to prevent the test needle from bending, but the result is subject to free fall; the test needle sinks during the entire test process The position should be at least 10mm away from the inner wall of the test mold. When the initial setting is approaching, it is measured every 5 minutes, and when the final setting is approaching, it is measured every 15 minutes. When the initial setting or final setting is reached, the test should be repeated once. When the two conclusions are the same, the initial setting or final setting state can be determined . The test needle should not be allowed to fall into the original pinhole during each measurement. After each test, the test needle must be wiped clean and placed back into the moisture curing box. The entire test process should be protected from vibration.

Alternative usage
Water demand for standard consistency (alternative usage) [1]
1 must be done before the test
a) The metal bar of the Vicat meter can slide freely;
b) Adjust the pointer to zero when the test cone contacts the top surface of the cone die
c) The mixer is operating normally.
2 Mixing cement paste
3 Determination of standard consistency
3.1 The use of alternative methods to measure the water consumption of cement standard consistency can be determined by either of the adjusted water quantity and the constant water quantity.
5ml。 When using the method of adjusting the amount of water to mix the amount of water to find water according to experience, when using the method of constant water, the amount of mixing water with 142.5ml.
3.2 After the mixing, immediately put the prepared cement paste into the cone mold, insert it with a knife, gently vibrate several times, and scrape off the excess
Clean slurry; after smoothing, quickly put it in a fixed position under the test cone, lower the test cone to the surface of the clean slurry, tighten the screw for 1-2s, and suddenly relax, let the test cone sink into the cement paste vertically and freely. The sinking depth of the test cone is recorded when the test cone stops sinking or the test cone is released for 30 seconds. The entire operation should be completed within 1.5 minutes after stirring.
3.3 When measuring with the method of adjusting water volume, the standard consistency is the pure paste when the test cone sinks to a depth of 28 mm and 2 mm. Its mixing
The amount of water is the standard consistency of the cement. The amount of water (P) is calculated as a percentage of the cement mass. If the sinking depth exceeds the range, the sample must be called another.
Adjust the water volume and retest until it reaches 28mm ± 2mm.
3.4 When measured by the constant water volume method, the standard consistency water consumption P (%) is calculated according to the measured test cone sinking depth S (mm) according to formula (1) (or the corresponding scale on the instrument).
P = 33.4-0.185S ····························· (1)
When the sinking depth of the test cone is less than 13mm, it shall be determined by the adjusted water volume method.

Use and maintenance
Before measuring the water consumption of the standard consistency, you should first check whether the sliding part of the instrument can freely slide in the bracket. At the same time, when the test rod is lowered to the surface of the clean pulp, the pointer should be aligned with the zero point of the scale, otherwise it should be adjusted.
Before measuring the setting time, the consistency test rod should be removed and replaced with a test needle. At the same time, check whether the pointer is zero when the test needle is in contact with the top of the round die, otherwise it should be adjusted.
Before each measurement, the instrument should be vertically stabilized, and should not be operated in an environment with obvious vibration.
After each measurement, the working surface of the instrument should be wiped clean and oiled to prevent rust.
The surface of the sliding rod should not be scratched or rusty.