Various types of vibrators are used to compact concrete, all kinds of bulk building materials and grain, in the manufacture of reinforced concrete products. Since concrete contains particles of different sizes, the most effective compaction can be achieved by vibrating at different speeds. A good vibrator concrete compacts quickly and efficiently.
Freshly poured concrete can contain 5 to 20 percent entrained air, ultimately reducing its density. Concrete with a high percentage of dispersed air will have reduced strength and increased permeability, which will significantly reduce the durability of a particular element during operation.
The basic principles of the vibrator operation are that vibration impulses sharply reduce the internal friction between the particles of the mixture, which allows the entrained air to rise to the surface, and heavier aggregates to settle under the action of gravity into a dense matrix. Vibrators for concrete are manufactured with vibration frequencies from 2800 to 15000 rpm. Poly-frequency concrete vibrators used for compacting hard concrete.
The amount of time that the vibrator must remain in the concrete will depend on the frequency and amplitude of the vibrator in the concrete. Frequency, the number of cycles of oscillation per minute, often expressed as revolutions or oscillations per minute. The frequency will have an effect on light masses, causing the mortar to liquefy. Amplitude is the maximum distance a point on the vibrating head can move from its resting position. The vibration amplitude will have an effect on heavier masses, and ultimately determines the radius of action or area of influence on the concrete.
