When using the concrete mixing machine to mix the concrete pouring components, the air bubbles must be eliminated. The use of a vibrating vibrator for tamping can make the concrete densely combined, eliminate the honeycomb and pockmarked surface of the concrete, so as to improve its strength and ensure the quality of the concrete components.
Requirements for concrete pouring
- The formwork should be watered and moist before pouring, and the cleaning openings of the wall and column formwork should be closed after removing debris and stagnant water.
2. The free fall height of the concrete falling from the bucket mouth shall not exceed 2 meters. If it exceeds 2 meters, the measures of adding cylinders must be taken.
3. When pouring vertical structural concrete, if the pouring height exceeds 3m, string tubes, pipes, chutes, or openings on the side of the formwork should be used.
4. When pouring concrete, it should be done in sections and layers, and the pouring height of each layer should be determined according to the structural characteristics and the density of steel bars. Generally, the layered height is 1.25 times the length of the active part of the plug-in vibrator, and the maximum is no more than 500mm. The layered thickness of the flat-plate vibrator is 200mm.
5. The plug-in vibrator should be inserted quickly and unplugged slowly, and the insertion points should be evenly arranged, moved point by point, and carried out in order, without any omissions, and achieve uniform vibrating. The moving distance is not more than 1.5 times the radius of action of the vibrating rod (generally 300~400mm). When vibrating the upper layer, 50mm of the lower concrete surface should be inserted to eliminate the joint between the two layers. The moving distance of the plate vibrator should be able to ensure that the plate of the vibrator covers the edge of the vibrated part.
6. Pouring concrete should be carried out continuously. If intermittent is necessary, the intermittent time should be as short as possible. And before the initial setting of the first layer of concrete, the second layer of concrete should be poured. The longest intermittent time should be determined according to all types of cement and the initial setting conditions of concrete. Generally, more than 2 hours should be treated as construction joints.
7. When pouring concrete, a special person should be sent to observe whether there is any displacement, deformation, or blockage of the formwork steel bars, reserved holes, embedded parts, inserts, etc. If problems are found, the pouring should be stopped immediately, and the pouring should be done before the initial setting of the concrete.
Types of concrete vibrator
According to the method of transmitting vibration, there are three types: internal vibrator, external vibrator, and surface vibrator:
1. Internal vibrator is also called a plug-in vibrator. When working, the vibrating head is inserted into the concrete, and its vibration wave is directly transmitted to the concrete.
This kind of vibrator is mostly used for vibrating concrete layers with a large thickness, such as bridge piers, abutment foundations, and foundation piles. It has the advantages of light weight, convenient movement, and wide use.
2. The external vibrator is also called the attached vibrator. It is a motor with a vibrating effect. A special bottom plate is installed on the bottom of the machine. The bottom plate is attached to the template during operation, and the vibration wave generated by the vibrator passes through The base plate, and formwork is passed to the concrete indirectly. This kind of vibrator is mostly used in the construction of thin-shell components, hollow slab beams, arch ribs, T-shaped beams, etc.
According to the needs of construction, in addition to the attachment type, there is also a vibration table for external vibrators, which are used to vibrate prefabricated concrete products. The preforms installed in the formwork are placed on the table surface connected with the vibrator, and the vibration wave generated by the vibrator is transmitted to the concrete preform through the tabletop and the formwork.
3. The surface vibrator is directly placed on the concrete surface, and the vibration wave generated by the vibrator 2 is transmitted to the concrete through the vibrating base plate fixed with it. Since the vibration wave is transmitted from the surface of the concrete, it is called a surface vibrator. When working, two people hold the handle of the vibrator and drag it according to the needs of the work. It is suitable for the construction of concrete roads and bridge decks with small thicknesses.