To make your structure strong and long lasting for its designed life, it is very important that your structure is nonporous or impermeable. Porous concrete can lead to various problems like leakages, corrosion etc. These can happen if proper compaction is not done during the placing of concrete.
Poor compaction results into following problems:
- Poor strength of concrete, which may lower the service life of the house or building.
- High porosity in concrete, which may leads to leakage in the house or building.
- Honeycombing in concrete, which may also leads to leakage in the house or building.
- Lower the durability of concrete, which may increase the chances of repair and maintenance of house or building.
Theoretically, compaction of concrete is the process adopted for expelling the entrapped air as far as possible from the fresh concrete to achieve the highest possible density of the compacted mass. It simply means that there shouldn’t be any void present in concrete.
The main purpose of compaction of concrete is to get a dense mass without voids, to get the concrete to surround all reinforcement and to fill all corners.
In the process of mixing, transporting and placing of fresh concrete, air bubbles are likely to get entrapped in the concrete. The lower the workability, the higher is number of air bubbles entrapped.
Air bubbles occupy between 5 to 20 percent volume of the total concrete. If the air is not removed fully, it can reduce the bond between the concrete and reinforcement and/or any other embedded parts and the structure may loses its strength considerably.
Compaction improves the fluidity of concrete and with the reduction of internal friction, packing of coarse aggregates take place. A well-compacted concrete is free of the loose pockets and air bubbles of entrapped air.
Voids reduce the strength of concrete and make a concrete permeable or porous. Therefore, experts are always follows the good concrete making practices to make the durable concrete. If you want to make a durable concrete, it is imperative that 100 percent compaction of concrete is one of the most important aims to be kept in mind. It must be borne in mind that compaction is important not only from the point of view of strength, but also from the point of durability.
Methods of Compaction of Concrete
Following are the different methods of compaction of concrete, which are given below:
01. Manual Compaction(Hand Compaction):
02. Mechanical Compaction by Vibration:
- Internal vibrator (Needle vibrator)
- Formwork vibrator (External vibrator)
- Table vibrator
- Platform vibrator
- Surface vibrator (screed vibrator)
- Vibratory roller
03. Compaction by Pressure and Jolting:
04. Compaction by Spinning:
Most of the repair and maintenance troubles may occur in the building due to bad practices in concrete construction i.e.
- Use of building materials which are not tested for quality.
- Poor batching of concrete
- Improper use of concrete admixture
- Bleeding in concrete
- Segregation in concrete
- Poor compaction of concrete
- Inadequate curing of concrete
Out of aforementioned practices, compaction of concrete generally troubles us more and it may ultimately results into home repair or home maintenance which may cost us fortune. We have already discussed the list of Do’s and Don’ts while concreting which makes concrete job very easy.