This document discusses different types of vibrators used in concrete construction. It describes internal vibrators, also called needle vibrators, which are inserted directly into wet concrete to consolidate it. Surface vibrators are used to compact horizontal concrete surfaces and include vibrating screeds, pan vibrators, plate tampers, and rolling screeds. Form vibrators are external vibrators attached to formwork that transmit vibrations to the concrete through the forms. The document provides details on the components, operation, and use of internal vibrators for effective concrete consolidation.

1. Prepared by
Prof. Ashish Makwana
Civil Engineering Dept. - MEFGI
1Prof. Ashish Makwana

2. PRESENTATION
OUTLINE…
• Piston pumps
• Squeeze type concrete pump
• Advantages of concrete pump Transportation
• Properties of concrete to be pumped
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3. Types of Vibrators
• Internal vibrators
• Surface vibrators
• Form vibrators
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4. 1. Internal Vibrators:
• An internal vibrator is also known as needle
vibrator.
• An internal vibrator essentially consists of the
three components.
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5. Fig. Internal VibratorProf. Ashish Makwana 5

6. (a) Power unit: It can be either a patrol engine or
electric supply unit.
(b) Flexible tube: It is a rubber tube having power
connecting device at one end and vibrator head
on the other end.
(c) Vibratory head: It is a straight iron tube having
eccentric weight fitted inside it.
• As the current passes through the tube, the
vibratory action is caused by the rotation of the
eccentrically weighted shaft at high speed
usually over 7000 r.p.m. which are transmitted to
the concrete particles.
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7. • The diameter of the needle varies from 2.0 cm to
17.5 cm and length from 25 cm to 90 cm.
• The frequency of vibration may vary from 10,000
to 15,000 cycles per minute.
• The bigger diameter needle is used in the
construction of mass concrete work.
• The vibrating head should be immersed
vertically in the concrete and should be kept
inside the concrete.
• While running the vibrator, its bearing should be
kept cool to avoid breakdown.
• As the concrete consolidates, its surface level
falls and surface becomes smooth.
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8. • Air bubbles may be seen breaking at the
surface.
• When these bubbles cease to appear on the
surface, the concrete may be assumed as
compacted sufficiently.
• The vibrator should be lowered vertically in the
concrete and when the concrete is compacted it
should be withdrawn vertically slowly at the rate
of about 8.0 cm/sec.
• At this speed the withdrawal hole caused will fill
itself without entrapping air in the concrete. Now,
the vibrator is inserted at another point at a
distance of 50 cm to 100 cm.
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9. Time of Vibration:
• The time of compaction by the internal vibrator
depends on the consistency of the mix.
• Usually from 5 to 30 seconds compaction is
sufficient depending on the consistency of the
mix.
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10. 2. Surface Vibrators:
• These vibrators are used to compact horizontal
concrete surfaces on roads.
• They impart vibration at the surface of the
concrete.
• The frequency of these vibrators vary from 3000
to 6000 cycles per minute.
Types of surface vibrators:
a) Vibrating screed
b) Pan type vibrator
c) Plate type tamper
d) Vibratory rolling screed
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11. 3. Form Vibrators:
• These vibrators are external vibrators and are
attached to the outside of the concrete form
work.
• They vibrate the formwork and in turn formwork
vibrates the concrete.
• This class of vibrators generally are used in
large precast concrete plants.
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