With the step-by-step development of domestic concrete injection technology, in response to the national environmental protection and green call, more and more injection operations are using wet concrete injection technology. In some large-scale water conservancy projects with international bidding, such as Ertan Hydropower Station, The Yellow River Xiaolangdi Project, the Three Gorges Project, etc., all use wet concrete spraying operations. Dry concrete jets generally do not exceed 5 m3/h. The use of wet concrete jets can reach 10m3/h for manual work and 20m3/h for robotic work.
According to the working principle of concrete wet spray machine, it is divided into two types: pumping type and pneumatic type. The pumping type is further divided into a plunger pump type wet spray machine and a screw pump type wet spray machine, and a hose squeeze pump type wet spray machine.
The plunger pump type wet spray machine uses a plunger type concrete pump as a basic body of a wet concrete jet machine, and a nozzle is installed at the outlet of the conveying pipe, and compressed air is introduced therein to spray the concrete. Such wet sprayers are generally bulkier but have a long transport distance.
The screw pump type wet spray machine transports materials by changing the volume of the joint space when the screw and the stator sleeve are engaged with each other. The main disadvantage of this model is the low productivity and the serious wear of the screw and stator sleeve, so the application range is not large.
The hose squeeze pump wet spray machine consists of a mixing bucket, a pumping hose, a pump body and a feed pipe. The pump body is cylindrical, and the planetary transmission mechanism in the middle drives the two rollers to rotate, and continuously squeezes the wet material in the pumping tube to make it flow into the delivery pipe. It has been reported that this type of jet has been widely used in foreign countries, but it has been rarely used since the introduction of domestic domestic products in recent years. The main problem is that the life of the extruded pipe is short.
Air-to-air wet concrete jets use compressed air to deliver material in a hose in a "lean flow" to the nozzle for direct injection. The machine is two tanks side by side, one jet and one stock. The bottom of the tank has a recumbent screw conveyor. The spray tank is filled with compressed air. The wet mix is fed into the feed pipe through the spiral. At the nozzle, the compressed air introduced through the gas ring ejects the mixture. The disadvantage of this wet spray machine is that it is troublesome to feed the tank, and the cleaning of the tank is also inconvenient.
Nowadays, the HSP type concrete spray machine is a common type of domestic application. The HSP type concrete spray machine is a new type of high-efficiency sneeze machine. It is mainly used for concrete spraying, which can make the mixture mix evenly and accurately control the water-cement ratio. It is conducive to the hydration of cement, so the dust is small, the rebound is small, the concrete is homogeneous and the strength is high. The machine is reasonable in structure, stable in performance, convenient in operation and maintenance, and long in service life. It is widely used in iron (gong) road tunnels, subways, hydropower projects, underground projects and shotcrete construction operations in mine shafts.
HSP type concrete spray machine greatly reduces the dust concentration near the machine and the nozzle during construction, eliminates the harm to workers' health; high productivity; low rebound; wet water spray, easy to control due to water-cement ratio, concrete The degree of curing is high, so the quality of the shotcrete can be greatly improved and the homogeneity of the concrete can be improved.