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Practical Tips for Using Concrete Vibrators in the Field

How to Use Concrete Vibrator in the Field Practical Tips

How to Use Concrete Vibrator in the Field Practical Tips

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Vibration is one of the methods used to consolidate poured concrete to achieve required density and, subsequently, the designated concrete strength. Vibrators (internal and external or shutter vibrator) need to be used properly and skillfully; otherwise, the concrete may get over vibrated or under vibrated; compromising the concrete quality in both cases.

That is why it is necessary to consider the practical tips obtained from construction standards such as ACI 309R-5 and field experiences for the correct utilization of vibration equipment and achieving vibration goals.

Practical Tips for Using Concrete Vibrators in the Field

Internal Vibrators

Figure-1: Square Pattern for Immersion Vibrators
Figure-2: Offset Pattern for Immersion Vibrators
Figure-3: Internal Vibrator Liquidity Low Slump Concrete
Figure-4: Holding Internal Vibrator at Almost Vertical Angle
Figure-5: Maintain the Distance Between Formwork Edge and Vibrator Head
Figure-6: Internal Vibrators
Figure-7: Using Several Vibrators to Consolidate Concrete to Increase Rate of Concrete Placement

External Vibrators

Figure-8: External Vibrators Attached to Formwork for Precast Concrete Construction
Figure-9: External Concrete Vibrator Attached to Steel Formwork
Figure-11: Proper Mounting of External Vibrator on Formworks

Table-1: External Vibrator Spacing for Consolidation of Concrete

Concrete consistencyConcrete slump, mm (inch)Distance between external vibrators, m (foot)
Very stiff or stiff concrete< 25 (1)1.524 (5)
Stiff plastic concrete25 – 50 (1 - 2)1.828 (6)
Plastic concrete50 – 127 (2 – 5)2.134 (7)
Flowing concrete> 127 mm (5)2.438 (8)


What is concrete consolidation?

Concrete consolidation is the process of reducing the volume of entrapped air, voids, and pockets of air in a freshly placed cementitious mixture, typically using manual or mechanical compaction methods.

How to determine the radius of influence of internal vibrators using field observation?

Determine influence radius in the field by noting how far from vibrator head bubbles escape from concrete. Alternatively, use an approximate distance of 1-1.5 times the radius of influence.

What happens if a poker vibrator is operated in the air?

Operating poker or an internal vibrator in the air would cause overheating and subsequent instrument failure.

Why is it important to maintain a formwork edge and internal vibrator space?

Maintain a 7-10 cm distance between the formwork edge and a vibrator head to avoid formwork damage.

How long should concrete be vibrated using internal or external vibrators?

Continue vibration until concrete levels in the form, coarse aggregate particles become embedded, a thin film of mortar forms on the top surface and along with the formwork faces, and the emergence of air bubbles from concrete stops.

What happens if the concrete is over vibrated?

If the concrete is over vibrated, it loses its consistency and suffers from segregation. Aggregates would settle to the bottom of the formwork, and cement paste would raise to the top of the element. As a result, the concrete strength reduces to honeycomb.


Read More

How to Consolidate Concrete in Congested Reinforced Concrete Members?

Compaction of Concrete: Methods and Results of Improper Vibration of Concrete

Types of Concrete Vibrator for Concrete Compaction

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