What aspects should be paid attention to when placing concrete?
Whether the concrete pouring is reasonable and correct is seriously related to the construction quality of the whole project. Therefore, on the issue of pouring, there should be no deviation from any engineering construction unit. For such an important project construction link, what requirements should we meet when it is completed, and what aspects should our builders pay special attention to?
Concrete should be poured before initial setting
If there is an initial setting phenomenon, a strong stirring should be carried out to restore the fluidity before it can be put into the mold; if there is a segregation phenomenon, it must be mixed again before pouring.
Free fall height of concrete
When pouring concrete, the free height of the concrete falling from the height should not exceed 2m, and the free fall height should not exceed 3m in the vertical structure. In order to prevent the concrete from segregation due to excessive free fall height. Before pouring the vertical structural concrete, the bottom of the pouring place should be filled with cement slurry or cement mortar with a thickness of 50-100 mm and the same composition as the mortar in the concrete.
Layered pouring of concrete
Concrete pouring should be carried out in layers so that the commercial concrete can be vibrated and compacted, and the upper concrete should be poured and vibrated before the lower concrete solidifies. The thickness of the concrete pouring layer should meet the regulations. Concrete pouring work should be as continuous as possible. For example, the upper and lower concrete pouring must be intermittent, and the long time interval (including the entire duration of transportation, pouring and intermittent) shall not exceed the regulations.
Retention and treatment of construction joints
If the concrete cannot be poured continuously due to technical reasons or limitations of equipment and manpower, and the intermittent time in the middle exceeds the allowable time, it shall be determined in advance to leave construction joints in appropriate positions. Because the bonding force between the old and new concrete is poor, it is a weak link in the component, so the construction joint should be left in the part where the structural stress (shear force) is small and easy to construct. Horizontal joints should be reserved for columns, and vertical joints should be reserved for beams and slabs.