When concrete is poured, it can have thousands of tiny air bubbles. There can be enough of these to significantly weaken the concrete. The standard solution is to use concrete vibrators.
These vigorously shake the concrete to eliminate any air bubbles by forcing them to the surface where the air can escape. In many cases, using a vibrator with poured concrete is a requirement under building codes following the International Standards. With pre-cast methods, a concrete form vibrator is used.
Internal vs External Vibrators
Using vibrators is an effective way to produce better consolidation and finishing of the concrete mix. There are two general types in use: internal vibrators that are immersed in the poured concrete, and external, which are attached to a pre-cast form which has been filled with a fresh concrete mixture.
There are some types of construction where internal vibrators can’t be used, such as constructing tunnels, or where extra reinforcement is required and the steel or mesh components are too close to one another.
External Concrete Vibrators
This requires a form that is made for use with an external vibrator. A concrete vibrator may come in different sizes and types, such as those powered by hydraulics or pneumatics (compressed air). Electrical form vibrators are typical where there is access to a 110-volt outlet or generator.
External concrete vibrators are available in air, electric and hydraulic models. Most operations using higher slump concrete favor pneumatic roller type concrete vibrators. These vibrators offer high frequency, light weight, reliability and low initial cost.
Heavy Duty Roller Vibrator
This type uses centrifugal force with a high frequency for reliable and relatively low vibrating of larger concrete pours, such as in pre-casting bridge beams or wall panels.
Turbine Vibrator
This is a pneumatic vibrator that utilizes an unbalanced turbine to create high frequency vibrations. It’s lightweight, quiet, and can operate smoothly in polluted or particle-heavy air.
Electrical External Vibrators
These typically use a rotary action to create the vibration. Those with a low frequency tend to be larger and heavier than air vibrators, and are often used with non-portable vibrating tables. But for high frequency vibrations an electric concrete form vibrator is usually quieter and much more efficient than an air-driven vibrator.
Form Brackets
Portable form brackets can utilize a male-female wedge design to provide fast, wrench-free movement of a small or midsize vibrator between form mounts. Various brackets are designed to accommodate roller, turbine or rotary electric vibrators.
At Del Zotto products, we’ve been in the concrete industry for more than 50 years. We are experts in pre-cast concrete methods and provide a range of quality equipment. Our products include a variety of forms, and each one comes with a form vibrator and mounting brackets to ensure pre-casting is done efficiently. Call us or stop by our facilities to learn more about our concrete products and equipment.