What is Compaction of Concrete and What are Concrete compaction Methods

What is Compaction of Concrete and What are Concrete compaction Methods

Freshly placed concrete is to be compacted well to make concrete dense and impervious

Compaction can either be done manually or mechanically. Manual compaction is done either by roding with steel rods or temping using wooden crossbeams. This method is usually employed for small jobs.

Mechanical compaction is done by using vibrators. These are very effective in compacting stiffer concrete resuting in highly dense and homoginus concrete which bonds well with the reinforcement.

Effective compaction enhances strength and its durability. In most of the RCC works needle vibrators are used to compaction.

Certain care is to be taken while using needle vibrators.

The needle of vibrator should be immensed vertically into concrete and it should remain vertically throughout the operation.

Concrete at a location should not be vibratated more than 15 seconds. The needle has to be withdrawn when its air bubbles sees to appears.

Vibrators to not be held touching the reinforcement. Tube of the vibrator should not be bent at sharp angles to avoid brinking.

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The spacing of the vibrators – 15 cm for 20 mm needle and 30 cm for 40 mm needle.

– Effective compaction makes the concrete dense and impervious

– Over-compaction leads to segregation

– Compacting concrete using vibrators is more effective than manual compaction

– Surface vibrators, setup on the concrete surface after placing, transmit vibrations to it through a working platform. They are generally employed in concrete road construction.

– Mechanical method of compacting the concrete is used only when the mix is stiff.

– Over-vibration or vibration of every wet mixes is harmful and should be avoided. Alternatively, concrete may be compacted manyally by rodding, temping or hammering.

– Rodding is generally done to compact thin vertical members while temping is done for compacting concrete for slabs etc…

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