Detailed description:

New standard operating procedures for Vicat apparatus

1. Before use, inject a small amount of wheel lubricant into the sliding part and check if it can slide freely up and down.

2. Determination of standard consistency: After mixing, immediately pour the prepared cement paste into the container

In the test mold already placed on the glass substrate, use a small knife to compact it, gently vibrate it several times, scrape off excess slurry, smooth it out, quickly move the test mold and substrate to the Vicat apparatus, and center it under the test rod. Lower the test rod until it contacts the surface of the cement slurry, tighten the screw, and suddenly relax it, allowing the test rod to sink vertically and freely into the cement slurry. Record the distance between the test rod and the bottom plate when the test rod stops sinking or is released for 30 seconds. After lifting the test rod, immediately wipe it clean. The entire operation should be completed within 1.5 minutes after mixing. The standard consistency of the cement slurry is the one that sinks the test rod into the slurry and is 6mm ± 1mm away from the bottom plate. The mixing water amount is the standard consistency water consumption (P) of the cement, calculated as a percentage of the cement mass.

3. Determination of initial setting time: The specimen is cured in a moisture curing box for 30 minutes after adding water for measurement. When measuring, remove the round mold from the moisture curing box and place it under the test needle, reducing the contact between the test needle and the surface of the cement paste. After tightening the screw, suddenly loosen it after 1-2 seconds, and the test needle should sink vertically and freely into the cement paste. Observe the reading of the pointer when the test needle stops sinking or is released for 30 seconds. When the test needle sinks to a distance of 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 in minutes.

4. Determination of final setting time: In order to standardize the sinking condition of the observation test needle, a circular attachment was installed on the final setting needle. After completing the initial setting time measurement, immediately flip the test mold and slurry down 180 ° from the glass plate by translation, with the larger end of the diameter facing up and the smaller end facing down on the glass plate, and then place it in a moisture curing box to continue curing. Measure every 15-1 intervals near the final setting time. When the test needle sinks 0.5mm into the test body, that is, when the circular attachment cannot leave any traces on the test body, it is considered that the cement has reached the final setting state. The time from when all the cement is added to water to the final setting state is the final setting time of the cement, expressed in minutes.

5. Attention should be paid to the measurement: During the initial measurement, the metal column should be gently supported and slowly lowered to prevent the test needle from hitting and bending. However, the result should be based on free fall. During the entire testing process, the position where the test needle sinks should be at least 10mm away from the inner wall of the test mold. Measurements should be taken every 5 minutes near the initial setting time and every 15 minutes near the final setting time. When reaching the initial or final setting, measurements should be repeated immediately. Only when the two conclusions are the same can the initial or final setting state be determined. Each measurement should not allow the test needle to fall into the original needle hole. After each test, the test needle must be wiped clean and the test mold should be placed back in the moisture curing box. The entire testing process should prevent the test mold from being subjected to vibration.