What are the precautions for wet spraying machine construction?
What are the precautions in the operation of the wet spray machine? The correct use of wet spraying machines, wet spraying trolleys and other equipment will help ensure the normal progress of construction and ensure the safety of construction personnel. For example, use mortar to lubricate the concrete wet spraying machine and the feeding pipe before spraying, and rinse the remaining concrete in the pipe with water after spraying, which can effectively extend the service life. During the operation of the wet spraying machine, the water-cement ratio should be strictly controlled. The suitable state is that the surface of the concrete has a layer of dim gloss; for the treatment of the seepage section, when the water volume is not large, blow it with high-pressure air before spraying, and then follow the normal construction procedure Proceed; when the water volume is large, bury the blind pipe close to the rock surface, and the spray point is from far to near, temporarily increasing the content of accelerator (≯6%) and gradually close.
Once the pipes of wet spraying machines, wet spraying trolleys and other equipment are blocked, immediately shut down, shut off the wind, and check and clear the pipelines. The time from concrete injection to the next cycle of firing is generally not less than 4h. After firing, the concrete should be inspected. If cracks occur, the firing interval or blasting parameters should be adjusted. When spraying concrete, strengthen labor protection to prevent concrete and rocks from collapsing and hurting people under the impact of high-pressure sprayed concrete. So how should we control when spraying concrete? It is important to check beforehand. The raw materials can only be used after passing the inspection, and the quick-setting agent should be properly kept to prevent deterioration by moisture. Strictly control the water-cement ratio of the mixture, and frequently check the working conditions of the accelerator injection link. The slump of shotcrete should be controlled within 140~180mm. During the spraying process, the rebound rate and actual mix ratio of the concrete should be checked in time. The rebound rate of shotcrete: the side wall should not be greater than 15%, and the arch should not be greater than 25%.
In addition to checking the materials, check the spray surface. If there are loose clods, they should be dealt with in time. The wet spraying machine should be arranged in a safe area and as close as possible to the spraying part, so that the operator can communicate with the spraying hand and adjust the working wind pressure at any time. When spraying, keep a proper distance between the nozzle and the sprayed surface, and the spraying angle should be as close as possible to 90° to achieve large compaction and small rebound. The nozzle should move continuously and slowly in a horizontal circular motion, pressing half a circle in one circle. The circular circle drawn by the sprayer is 40~60cm in the horizontal direction and 15~20cm in height; if the spray surface is covered by a steel frame or steel mesh, the nozzle can be used. Slightly skew, but not less than 70°.
After the spraying work of the wet spraying machine is completed, the construction personnel should check the bonding between the sprayed concrete and the rock surface. At the same time, measure its flatness and section to confirm whether the thickness of the shotcrete meets the design and specification requirements. The wet spraying machine and wet spraying trolley of Saintyol DAWIN Machinery have been widely used in construction and played an important role.
