HIGH FRECUENCY EXTERNAL VIBRATORS
15
en
VEAF
10. RECOMMENDATIONS OF USE
10.1. APPLICATIONS OF EXTERNAL VIBRATORS
External vibration is used in many fields, ranging from the vibration of prefabricated concrete units to the
movement of material.
Here will not go into detail for the use of external vibrators. Here will be shown the most common
applications for external vibrators.
10.2. VIBRATION OF FORMWORKS
Formworks are used to vibrating beams, prefabs, walls, pipes…
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The mould must be a rigid steel structure and the external vibrator must be strongly attached to the
mould. If it is possible, mould must rest on an elastic base.
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External vibrators must be distributed over the surface of the mould to get accelerations of 1,5g.
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External vibrators must be chosen to get this acceleration.
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As recommendation, the external vibrators should be chosen to get the weight of the mould x 1,5.
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To achieve the centrifugal force is better to get more vibrators with less centrifugal force than less
vibrators with more centrifugal force.
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Distance between vibrators is between 1,5m and 2,5m.
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Only a depth of 30cm (maximum) is the effect of an external vibrator. If it is necessary, external
vibrators must be installed on both sides.
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Vibrators can be regulated and it is recommended to adjust the centrifugal force until the optimal
vibration is obtained.
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The external vibrators must be chosen to avoid it works at a maximum level.
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Según el tipo de estructura se recomienda combinar la vibración externa con la interna.
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External vibrators should be positioned on the ribs of the mould used for the prefabrication.
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The centrifugal force required depends on the size and shape of the prefabricated unit and on the
mass of the concrete.
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Vibration time must be adjusted individually for each case. Normally, the vibration time should be 1-
2,5min
Equation for calculating the necessary centrifugal force:
Centrifugal force:
F= C(A+0.2B)
