The concrete placement capability of vibrator changes with various terms and conditions (slump, size of aggregate, vibration capability of vibrator and a mixture agent etc.).For example, the maximum capability of HIB150H hydraulic vibrator (the biggest vibrator that has 150mm diameter head) is still 25 M3 per hour at the condition of the concrete slump 3 and aggregate size 150mm. Similarly, at least two 40mm vibrators are required when placing concrete mix transported by a pump that transports 30M3 concrete mix per hour (even the concrete mix is slump 18 for construction). As a situation seen from the high frequency vibrator (diameters 30-60mm) currently generally used, vibration transfer is influenced by the diameter of vibrator when compare the performance between low slump 2.5 and high slump 12.0. Moreover, it is known that the rate of transfer is larger; the rate of attenuation is large in high slump concrete mix. Most of the cases, 10 - 20 seconds of initial vibration are the most effective in vibration time, and the rate of vibration transfer is fixed even more vibration is applied at the same place. Thus, with the character of an vibration characteristic or concrete, please make reference the "concrete placing capability standard table" of the following table after understanding that the efficiency of concrete placement is influenced greatly.

Pitch vibration part diameter, concrete placing range

* Conditions of the above table: (Either in civil engineering works or construction, construction slumps also differ. With plain concrete, it shall consider as slump 8cm, and the concrete placement domain by substitution of vibrator shall not overlap)

Although surely construction cost must reduce, worker, and vibrator should carry out sufficient preparation. Failure of placing will do an empty thing the design, temporary construction, the foundation, which have suffered troubles until now and all other work.

Concrete placement will be finished when cylindrical vibrator seems to have inserted less than for every effective range, for reduction of concrete capacity to have stopped, and for paste to have surfaced on the average on the surface, and to have worn light. In the case of drawing out of vibrator, it pulls up slowly so that a hole may not remain. In addition to the above foundations, be careful especially of the following point.

1. Since joint portion of placed concrete mix serves as a weak point of a structure, it needs to build the whole on a single object without joint portion as much as possible.
   For this reason, the work division defined beforehand must place concrete continuously until it finishes.
   Moreover, you have to prepare the vibrator of fixed sufficient number.
   
   
2. When the portion which rough aggregate divided under an injection of concrete or into finished part is made, please dip up the separated rough aggregate, bury it in [which is a certain concrete enough] mortar, and fully apply vibrator.
   
   

   Dip up a portion with many gravels, put it into a soft place, and fully apply vibrator.

   

   Put soft concrete to a place with many types of gravel.

3. If insert vibrator 10 cm in lower concrete and re-vibrates the vibrator at a narrow interval when concrete is driven into the upper part and lower concrete is beginning to become hard a little, a very good result will be obtained.
   Under this circumstance, if delay material is beforehand added moderately to lower concrete, the time suitable for re-vibration can be extended, and it will be useful also to prevention of a cold joint. This method is called two-layer placement.
   
   
   * "Cold-Joint" is a phenomenon that causes a separation between soft concrete and the concretes driven in previously when placing a lot of concretes continuously or placing the concrete using quick harden agent.
4. In placing concrete mix to a slope and cone slope, surely begin an injection from a lower part, and it is begun giving vibration from the bottom. That is because it is well stabilized by the dignity of the concrete struck later and vibration.
   On the contrary, if it begins giving vibration from the upper part of a slope, there is a tendency that pulls upper concrete. If vibration is applied especially in a lower part, for the reason, it will begin to flow and support of upper concrete will be lost.