Concrete vibration essentials and precautions

First, the essentials of vibration

1, vertical insertion, insertion should be fast, pull out slowly, so as not to leave a gap in the concrete.

(2) The time of each insertion vibration is about 20-30 seconds, and the concrete is no longer significantly sinking, no bubbles appear, and the grouting begins to prevail.

3, vibration time should not be too long, too long will appear sand and cement separation, stone sinking, and the formation of sand layer on the surface of the concrete, affecting the quality of concrete.

4, vibrating vibrator should be inserted into the lower concrete 10cm to strengthen the combination of upper and lower concrete.

5. The spacing before and after vibration insertion is generally 30-50cm to prevent leakage vibration.

6, vibrating do not touch the template, steel and embedded parts, vibrating near the template, should be used at the same time to tap the template, in the dense reinforcement and template corners, should be combined with the use of iron.

Second, vibrating precautions

1. The staff must know the principle of concrete vibration, and make detailed pouring plans for the poured concrete, such as pouring thickness, how to pour, construction joint reservation position, etc., in addition, it is necessary to list and summarize the possible problems and solutions to prevent the phenomenon of arbitrary construction.

2. Concrete should be poured in layers, and can be adjusted according to the weather conditions of the day, but generally not more than 30cm.

3. The vibrating time should not be too long or too short, which requires the relevant staff to accurately handle the vibrating time. If the vibration time is too long, it will produce segregation and bleeding stratification. If the vibration time is too short, the compactness of the mixture will be poor. Therefore, the concrete should no longer sink, no longer appear bubbles, and the surface is flat as the standard to determine whether it is dense, and the vibration time in one part should not be less than 10s.

4. The insertion points of the plug-in vibrator should be arranged evenly, and it should be quickly inserted and slowly pulled out, one by one. The vibration movement interval is generally within the range of 30~40cm, or no more than 1.5 times the vibration radius. When vibrating the concrete near the side mold, the distance between the vibrator and the side mold should be controlled within the range of 5~10cm.

5. In the process of vibration operation, when each place is vibrated, the vibration plate should be slowly put forward while vibrating, and the template, steel bar, embedded parts, etc. should not be collided to prevent the steel bar from being displaced and the template from being deformed due to vibration.

6. Need to be equipped with spare machinery on site, because the long-term use will cause the machinery to heat up, and even burn the instrument, so configure a spare vibrator can make one machine is working at the same time, the other machine suspended to cool down, so as to ensure the smooth construction.

7. Determine the time of each insertion of the vibrator according to the conditions of obvious subsidence and bubbles no longer appearing in the concrete, and it should be controlled within the range of 20 to 30 seconds.

8. When vibrating the upper layer, the vibrator should be inserted 10cm into the lower concrete to achieve a firm combination between the upper and lower layers of concrete.

9. The relevant management personnel should select the vibrator according to the essence and actual situation of the project. Vibrators are divided into low frequency, medium frequency and high frequency. Low frequency: 1500~3000 times /min; Intermediate frequency: 5000~8000 times /min; High frequency: more than 10000 times /min. Low frequency should be selected for large stone particle size, and high frequency should be selected for large slump of mixture.

10. Relevant staff also need to master the skills of using a variety of vibrators together to facilitate engineering construction.