External vibrator
The external vibrator (also called the formwork vibrator ) is a construction device that is used to compact fresh concrete . In contrast to the internal vibrator , the external vibrator is not inserted into the concrete, but attached to the outside of the formwork . In the external vibrator there is a compressed air or electric motor with which an imbalance is driven. The vibrations generated by the imbalance are transmitted through the formwork into the fresh concrete and, in a certain area of action, lead to a denser storage of the aggregate and to an escape of the air trapped in the concrete. In this way, the concrete reaches the required strength and frost resistance after hardening . In addition, the bond with the reinforcement is significantly improved.
External vibrators are listed in the BGL / EUROLISTE under code number B.9.2 - External vibrators . The parameter is the generated centrifugal force in kilonewtons .
application
There are several areas of application for external vibrators. The external vibrator is used on the construction site wherever internal vibrators cannot be used. This is the case, for example, when concreting a tunnel wall. Another area of application is the production of precast concrete parts in the factory. There, for example, tilting tables or stair molds are equipped with external vibrators. In these cases, the vibration speed is usually between 4500 and 6000 revolutions per minute. In order to avoid breakage of the formwork, the output of the external vibrator is matched to the rigidity of the formwork. In addition, careful planning of the fastening points in terms of number and location is required. For the most even compaction effect possible, the external vibrators are usually attached to the nodes of the formwork reinforcements.
External vibrators with a frequency of 50 Hz and 1500 to 3000 revolutions per minute are used to drive conveyor troughs, sieving and sorting systems as well as for the uniform emptying of silos and containers. They also enable the cleaning of filters in dedusting systems.
See also
- List of construction machinery and construction equipment
- List of construction machinery manufacturers
Web links
Individual evidence
- ↑ Main Association of the German Construction Industry: BGL Construction Equipment List 2015 . Bauverlag, 2015, ISBN 978-3-7625-3670-3 .
- ↑ Horst König: Machines in construction: Basics and application . Vieweg + Teubner Verlag, 2008, ISBN 978-3-8351-0250-7 , pages 26-27.