Compaction Equipment

Two types of vibrators are common on building sites - immersion (poker) vibrators and surface vibrators. Each has its sphere of application, although on floors and other flatwork it is not uncommon for one to augment the other. A third type, for vibrators, are commonly used in precast work, and sometimes on building sites (this is not covered here).

Immersion Vibrators

Frequently referred to as 'poker' or 'spud vibrators', immersion vibrators consist essentially of a tubular housing which contains a rotating eccentric weight. The out-of-balance rotating weight causes the casing to vibrate and, when immersed in concrete, the concrete itself. Depending on the diameter of the casing, and on the frequency and amplitude of the vibration, an immersion vibrator may have a radius of action between 100 and 600mm (see Table 1)

Immersion vibrators may be driven by:

  • A flexible shaft connected to a petrol, diesel, or electric motor
  • An electric mortar situated within the tubular casing
  • Compressed air

 Diameter of Head (mm)  20-40  30-60  50-90  80-150  130-180
 Recommended Frequency (Hz)  150-250  140-210  130-200  120-180  90-140
 Average Amplitude(mm)  0.4-0.8  0.5-1.0  0.6-1.3  0.8-1.5  1.0-2.0
 Radius of Action (mm)  80-150  130-250  180-360  300-500  400-600
 Rate of Concrete Placement (m³/h per vibrator)  0.8-4  2.3-8  4.6-15  11-31  19-38
 Application  High slump concrete in very thin members and confined spaces.
May be used to supplement larger vibrators where reinforcement or ducts cause conjestion in forms
Concrete 100-150mm slump in thin walls, columns beams, precast piles, thin slabs and along construction joints. May be used to supplement larger vibrators in confined areas Concrete (less than 80mm slump) in normal construction, eg walls, floors, beams and columns in residential, commercial and industrial buildings  Mass and structural concrete of 0-50mm slump deposited in quantities of up to 3m³ in relatively open forms of heavy construction Mass concrete in gravity dams, large piers and massive walls etc