Vibrating tables remove unwanted entrapped air from concrete. This eases concrete placement, provides greater strength and density, creates homogeneity, and reduces air pockets for an improved product finish. The tables consist of a table top, a vibratory motor, and shock absorbers. The concrete mold is either clamped or set on top of the table, and then vibrated to consolidate the concrete.
Two basic types of tables are used most frequently for consolidating concrete. The first is the flat-top table. It has a smooth surface onto which the mold is set. Vibratory motors are attached to the table to move the concrete in the mold. The second type of table is a grid-top table. This type of table is usually associated with a conveyor system. The mold is rolled onto the grid, raised, vibrated, and then lowered back to the conveyor.
When choosing a vibrating table it is important to consider the maximum load of the table: the weight of the mold and concrete along with the table top and motor make up the weight that the table will lift. Another factor to consider is slump. The drier the mix, the higher frequency the table will need to vibrate at to properly consolidate the concrete.