What is Concrete Compaction | Method | Types | Hand Compaction | Mechanical Compaction | Pressure and Jolting Compaction |

What is Concrete compaction

Compaction of concrete – In the concrete the process of mixing of concrete, transporting of concrete and placing of concrete Void (air) is likely to get entrapped in the fresh concrete. Compaction of concrete is a process followed to remove the entrapped air from the concrete.

The lower the workability, concrete mixes have a higher amount of entrapped air that contain a higher percentage of entrapped air and therefore will require more compacting efforts then higher workable mixers.

We should always keep in mind that there should be 100% compaction. Lack of compaction also affects strength, durability, and permeability. Which is very important in our concreting. Durability becomes more important than strength of concrete. Inadequate compaction increases the permeability of concrete resulting in easier Penetration for aggressive chemicals in the solute, which attack the concrete and important reinforcement attack, reducing the durability of concrete and reinforcement. That’s why we always have 100% compaction in concrete.

Note – If 5% void remains in our concrete than our concrete will be reduced the strength about 30% and 10% void remains in our concrete than our concrete will be reduced the strength about 50%. 100% compaction in concrete and maximum density with reasonable compacting efforts available at sites.

What is concrete compaction?

Method of compacting of concrete

Following method of compacting of concrete: –

1. Hand Compaction
2. Mechanical Compaction
3. Compaction by Pressure and Jolting
4. Spinning Compaction

Hand compaction of concrete

Hand Compaction – Hand compaction of concrete is generally used for the unimportant concrete work, of a small magnitude. In other things hand compaction is also used for that case where a large quantity of reinforcement is used. In the large quantity of reinforcement mechanical compaction cannot be normally compacted of concrete. Hand compaction is done for the rodding, ramming, and tamping. This is a hand compacted tool. The consistency of concrete is maintained at a higher level.

Hand compaction tools

1. Rodding
2. Ramming
3. Tamping

Compacting of concrete by rodding

Rodding – In this method a piece of bamboo, iron rod is used for rodding for compaction of concrete.

The thickness of the concrete layer is limited to about 15 cm to 20 cm. Rodding is poking the concrete with a roughly 2 m long, 16 mm diameter rod at sharp corners and edges to pack the concrete between the reinforcement.

Compacting of concrete by ramming

Ramming – Ramming is used for the compaction of plain concrete, ground floor construction or un reinforcement foundation concrete.

Ramming compaction is not used for the reinforced concrete, above ground floor construction and where the support of the formwork. If we used a ramming compaction upper floor construction reinforcement and formwork may fail.

Compacting of concrete by tamping

Tamping – Tamping is used for the compaction of roof, floor slab or road pavement. where the thickness of concrete is comparatively less, and the surface is smooth and level. The wooden cross beam must hit the top surface by the concrete. Wooden cross-section beam of 10 cm Ⅹ 10 cm is used in tamping compaction. [Consistency of soil]

Mechanical compaction of concrete

Mechanical Compaction – Hand compaction is complete only when we have sufficient workability in concrete. Only then the hand compaction process is completed in good manner. But on the other hand, our concrete structure also becomes low strength due to more water cement ratio. but when high strength is required in our concrete it is necessary to have a stiff concrete with low water cement ratio. To compact such concrete mechanical compaction (vibrator) is to be used.

For the use of vibrator low slump about stiff mixes for production of high-quality concrete with required strength and impermeability. Vibrator is very important if we have a bad aggregate, bad shape, and texture.

Mechanical compaction tools

1. Needle Vibrator
2. External Vibrator
3. Table Vibrator
4. Surface Vibrator
5. Roller Vibrator
6. Platform Vibrator

Compacting of concrete by needle vibrator

Needle Vibrator – Needle vibrator is also called internal vibrator, Poker vibrator or Immersion vibrator. Internal vibrator is the most used vibrator in our construction site in comparison of another vibrator. In this vibrator needle is penetrated the concrete and vibrator is started until all the voids are not removed. We have many types of needle vibrator is available whose diameter Varies from 20 cm to to 75 cm and needle vibrator length Varies from 25cm to 90cm. According to construction site we used all these types of vibrators, if our construction site is bigger, we use vibrator with maximum diameter. and if the construction site is less thickness, then we use a small diameter needle vibrator.

In needle vibrator shafts and motors are attached and operate mechanically, the frequency of vibrator is 12000 cycles of vibration per minute.

Compacting of concrete by external vibrator

External vibrator – External vibrator is also called a formwork vibrator. External vibrator is used for the complicated members or where reinforcement Is highly congested.

Formwork vibrators are used for columns, walls, and precast units. External vibrating device is attached with the outside of the formwork and formwork is transferred to the vibration to the concrete. External vibrator consumes more power compared to the comparable Needle vibrator due to the above reason. Formwork vibrators will give a better and smooth finish.

Compacting of concrete by table vibrator

Table vibrator – Table vibrator has powerful vibrating units. In a table vibrator, vibrator machine is clamped into the table and vibrator transfers to the vibration into the table. Table Vibrator is used for the compaction of concrete cube and other packing material kept on the table gets vibrated.

Compacting of concrete by surface vibrator

Surface Vibrator – Surface vibrators are also called Screed board vibrators.

Surface vibrators used for thin slab concrete members like, roof slab, floor slab and Road surface. Surface vibrator is effective for about 15cm thin concrete members.

Surface vibrators are mounted on Screed Board and generally used for compacting, levelling, and finishing the bridge floors, roof floor, road slab, bridge floor etc.

In thin concrete members needle vibrators, External vibrators and other types of vibrators are not easily effective. In such conditions, a surface vibrator is to be used. Generally, Floor slabs and roof slabs are compacting for surface vibrators.

Compacting of concrete by roller vibrator

Roller Vibrator – Roller vibrators are used for the compacting of dry concrete and lean concrete. Hence, this type of concrete is called Roller compacted concrete.

Roller vibrators are generally used for very heavy construction Like dams, road pavement bridges etc.

Compacting of concrete by platform vibrator

Platform Vibrator – Platform vibrator is the same as the table vibrator. but is available in large size compared to table. Platform vibrator is used for the compacting of railway sleepers and manufacturing of prefabricated concrete elements.

Pressure and jolting compaction of concrete

Pressure and jolting – Pressure and Jolting compaction methods are used for compacting hollow blocks, Cavity blocks and Solid concrete blocks. In this method very dry concrete is vibrated, Pressed, and given jolts.

This compaction Method concrete having very low water cement ratio gives high yielding strength.