1. Requirements and treatment of formwork
There are two kinds of formwork: wood formwork and steel formwork. The formwork surface shall be cleaned before use, and no dry hard cement mortar and other debris shall be adhered. The wood formwork shall be fully wetted and cleaned with clean water, without ponding, and the formwork gap shall be tightly spliced. When pouring commercial concrete, we should always pay attention to the formwork, support, caulking, etc. when we find that the formwork moves, we should immediately stop pouring and repair it as soon as possible.
For the non bearing formwork, when the strength of commercial concrete reaches 2.5MPa, the commercial concrete will not collapse again due to the removal of formwork. This period is about 3-4 days. For the removal date of load-bearing formwork, it can be removed only when the commercial concrete reaches 70% of the strength. It is necessary to prevent premature removal of formwork.
2. Mixing of commercial concrete
The feeding sequence of commercial concrete is as follows: first, we will load stones, cement and sand into the hopper in proportion. Then add water into the drum, or add water when the hopper is feeding. In this way, the cement can be sandwiched between sand and stone when the hopper loads the material into the drum, which can achieve good effect. At the same time, in the mixing of commercial concrete, to strictly control its mix proportion is the key, to often check, so as to ensure that the measurement of materials is very accurate.
In addition, we should also pay attention to the characteristics and quality of some admixtures, so that we can reasonably control the admixtures. Promote the mixing of commercial concrete more uniform. To achieve this effect, the mixing time of commercial concrete must not be too long. If the mixing time is too long, the workability of commercial concrete will be reduced, and the efficiency of mixer will be greatly reduced.
3. Pouring of commercial concrete
Commercial concrete must be poured before setting. If commercial concrete sets before pouring, we can mix it again, so as to return to the original state. Before pouring the commercial concrete, if there is segregation of the commercial concrete, we also need to re mix the commercial concrete, so that the pouring can be carried out. When pouring commercial concrete, in order to avoid segregation, we should ensure that the falling height of commercial concrete is not more than 2m.
When pouring the commercial concrete of the floor, it is necessary to ensure that the fall of the commercial concrete does not exceed LM. If the fall of commercial concrete exceeds these heights, we should take measures such as tumbling barrel, chute and so on. The chute used is usually made of wood nailed, and its surface is covered with iron sheet. When using the chute, its inclination angle shall not exceed 30 degrees. The tandem cylinder is mainly made of thin steel plate, and each cylinder is about 70cm long. It is connected by hook and loop, and buffer baffle is installed in the cylinder. At the same time, the commercial concrete should be poured layer by layer, so that it can be poured and tamped at the same time.