To make your structure strong and long lasting, 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 after placing of concrete.
Compaction of concrete is the process adopted for expelling the entrapped air as far as possible from the concrete to achieve the highest possible density of the compacted mass.
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.
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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 a number of air bubbles entrapped.
Also Read: What is the Workability of Fresh Concrete?
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 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, it is imperative that 100 percent compaction of concrete is one of the most important aims to be kept in mind in good concrete-making practices. 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. Compaction is done in different methods, which are given below.
01. Manual compaction
02. Mechanical compaction with vibrators