Why Compaction/Vibration is Very important in Concrete

     Hi there, Welcome to "The Civil Engineer", In this article we explained what is Compaction/vibration of concrete is and why it is important. 

What and Why vibration?

    Concrete is very vital for building if it is a concrete structure. When it comes to the strength of concrete it depends on various factors like the water-cement ratio etc., Like that one of the important factors that determines the strength of the concrete is Compaction/Vibration of concrete which refers to the concrete being free from air particles, or free from air bubbles. To make the concrete free from air bubbles, vibrators were used, the process behind vibration is that when concrete is vibrated, the aggregates move slightly from their poured position so that air trapped between aggregate gets released.

Effects of Air Bubbles on Concrete 

    So, Literally, the important function of Vibration is to prevent the presence of air bubbles in the concrete. What happens if air bubbles are present inside the concrete. The air bubbles result in the pour binding of concrete thus reducing the strength of the concrete. Because tightly packed concrete will result in perfect and increased strength.

Time limit for vibrator in concrete

     Vibration by using the vibrators need not exceed 15 to 20 seconds more than that will create segregation (Separation of aggregates and cement mortar) which is not good for concrete.

How to check whether proper vibration is done or not?

    If Vibration is done properly there will be no or minor honeycomb formation in the concrete. If there is a major or numerous minor honeycomb in the concrete then more air bubbles are present in the concrete and vibration is not done properly.

Different Types of Vibrators Present in the Market

    Various types of vibrators are available in the market such as

1. Immersion Vibrator
2. Surface Vibrator
3. Form Vibrator

Immersion Compactor/Vibrator

    Immersion Vibrators are commonly known as "poker" or " Needle" vibrators. They rotate with an eccentric weight which causes the vibrator to ripple the vibration throughout the concrete. The vibration created by these vibrators goes up to 150mm deep. An immersion vibrator can also be used for deep column vibration by adding an additional shaft up to 12m deep. The vibration created by the Immersion vibrator melts the two different layers of the concrete into a single one.

Surface Compactor/Vibrator

    Surface vibrators are used for vibrating a large area like concrete Slabs, Concrete roads, etc., The vibration produced by the surface vibrators is made by giving a downward thrust over the surface. These vibrations don't reach very deep hence surface vibrators are complemented by immersion vibrators. Surface vibrators remove the air voids just below the surface and fill it with the surrounding concrete. Hence we will get a clear smooth finished surface.

Form Compactor/Vibrator

    Form vibrators are called external vibrators. These vibrators are used where high-density reinforcements are used. In High reinforcement, normal vibrators like immersion or surface won't work. Hence form vibrators are used. Form vibrators are fixed to specially made form works(Shuttering work). Once the vibrator is started the vibrator vibrates along with the formwork, hence achieving the required compaction.

    Use a Suitable vibrator for the required work.