Precautions should be taken during placing of concrete.
Following precautions should be taken during placing of concrete. • The formwork or the surface which is to receive the fresh concrete should be properly cleaned, prepared and well watered. • It is desirable to deposit concrete as near as practicable to its final position. •The large quantities of concrete should not be deposited at a time. Otherwise the concrete will start to flow along the formwork and consequently the resulting concrete will not have uniform composition. •The concrete should be dropped vertically from a reasonable height. For vertical laying of concrete, care should be taken to use stiff mix. Otherwise the bleeding of concrete through cracks in forms will take place. The term bleeding is used to mean the diffusion or running of concrete through formwork. •The concrete should be deposited in horizontal layers of about 150 mm height. For mass concrete, the layers may be of 400 mm to 500 mm height. The accumulation of excess water in upper layers is known as t...