06-16-2022, 12:03 PM
MECHANISATION OF CONCRETING
CONCRETE PLACING BY PUMPING
Taken from : Ambuja Technical Literature Series -13
PLACING OF CONCRETE
Concrete is often transported to its final position by a number of methods. Even though it is desirable to place the concrete directly into position, it is not always possible to achieve the same. However, placing can be done to the desired quality if following recommendations are carefully observed .
for more details download .....
CONCRETE PLACING BY PUMPING
Taken from : Ambuja Technical Literature Series -13
PLACING OF CONCRETE
Concrete is often transported to its final position by a number of methods. Even though it is desirable to place the concrete directly into position, it is not always possible to achieve the same. However, placing can be done to the desired quality if following recommendations are carefully observed .
- Deposit the concrete at or as near as possible to its fin al position. Use of shovel or poker vibrator to push the concrete to its desired position may lead to segregation.
- Place the concrete in uniform layers so that no segregation takes place. In walls and columns, in order to prevent air entrapment, the layer thickness should be restricted to 450 mm while placing.
- There is no need to restrict the height from which concrete is dropped so long as the mix is cohesive and the drop is unobstructed and through a
tremie or a pipe chute.
- Segregated mixes due to bad placing cannot be fully compacted.
- Place concrete as quickly as possible. However, the placed concrete must also be compacted at the same time.
- Before placing each layer the lower layer must be fully compacted.
- Avoid cold joint formation by placing the layer of concrete over the previous layer which can still be compacted.
- In columns and walls the placing must be done in such a manner that concrete does not strike formwork, reinforcement or inserts. Any obstruction along the path of placing will cause segregation and the mortar (finer portion) of the concrete mix will stick to the reinforcement and formwork while coarse particles will drop below.
- Always make sure, the location at which the concrete is being placed is visible to the naked eye.
- For good and uniform finish in wall and columns it is necessary to fill the forms at a rate greater than 2.0 to 3.0 m height per hour.
for more details download .....
