Concrete, as soon as it comes out of the mixer or is ready for use on the platform, is transported and placed on the formwork.

Precautions for placing concrete
Precautions for placing concrete

The following precautions should be taken while pouring concrete.

  1. The formwork or surface must be well cleaned, prepared and well watered in order to obtain fresh concrete.
  2. It is desirable that the concrete be deposited as close to its final state as possible.
  3. Large amounts of concrete should not be deposited in one go. Otherwise the concrete will flow along the formwork and the resulting concrete will not have a uniform structure.
  4. Concrete should be dropped vertically from an appropriate height. For vertical laying of concrete, care should be taken to use a hardening mix. Otherwise the concrete will bleed through the cracks in the forms. Bleeding is the term used to describe the spreading or running of concrete through the formwork.
  5. Concrete should be deposited in horizontal layers of about 150 mm in height. For massive concrete, the layers can range in height from 400 mm to 500 mm. The accumulation of excess water in the upper layers is known as latteness and must be prevented by overfilling the shallow layers with a stiff mix or by pouring dry batches of concrete to absorb the excess water.
  6. As far as possible, the concrete should be kept to the same thickness. In case of deep sections, concrete should be laid in successive horizontal layers and due care should be taken to develop adequate bond between successive layers.
  7. Concrete should be well worked around the reinforcement and tapped in such a way that no honeycomb surface is visible when the formwork is removed. The term honeycomb is used for the comb or mass of waxy cells formed by bees in which they store their honey. Therefore, if this precaution is not taken, the concrete surface thus formed will have a honeycomb-like surface.
  8. Concrete should be laid on the formwork as soon as possible. But in no case should it be applied after 30 minutes of preparation.
  9. While laying, it should be observed that all the edges and corners of the concrete surface remain in unbroken, sharp and straight line.
  10. The placement of concrete should be done seamlessly between predetermined construction joints.

Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.