Concrete spraying machine working principle and classification

The machines used to spray concrete are collectively referred to as concrete shotcreting machines. Used to spray concrete construction operations. It is a machine for preventing sand and dirt on the inner wall of the tunnel from falling, preventing landslides and preventing landslides. Widely used in tunnels, culverts, subways, bridges, coal mines, high marsh mines, hydropower projects, underground engineering, construction and other protective engineering machines.

First, the working principle

The compressed air is used to continuously transport concrete along the pipeline and spray it onto the construction surface. There are two types of sub-dry sprayer and wet sprayer. The former is pneumatically conveyed dry mix material and mixed with pressurized water at the nozzle. The latter is sprayed by a pneumatic or concrete pump conveying concrete mixture through nozzles.

Second, concrete spraying machine classification

A. According to the method of adding water to the concrete mix, it can be divided into three types: dry, wet and semi-wet.

1. Dry-type cement and aggregate are mixed according to a certain proportion, and after being evenly mixed, the compressed air is blown to the nozzle and the pressure water from the pressure tank is mixed and sprayed. In this way, the construction method is simple and the speed is fast, but the dust is too large, the springback loss of the ejected material is large, and high-grade cement is used. Most of the domestic production is dry.

2. Wet-entering jets are filled concrete mixes. As a result, the dust content in the jet is low, and the rebound amount is also reduced. This is an ideal injection method. However, wet materials tend to condense in the feed line, causing plugging and troublesome cleaning, and thus cannot be used widely.

3, semi-wet type is also called tidal type, that is, the concrete mixing material is moisture content of 5%~8% moisture content (by volume), this material reduces the dust when spraying, because the adhesiveness is smaller than the wet material, non-stick Cans are dry and wet improvements.

B. According to the jet machine structure type, it can be divided into cylinder tank type, spiral type and rotor type.

1、Cylinder type tank spray gun is strong and durable. However, the body is too heavy. The opening and closing of the upper and lower bell-shaped valves requires heavy manual operations, labor intensity, and easy to cause blockage, so it has been phased out.

2. The spiral screw jet has a simple structure, small size, small mass, and good maneuverability. However, when the conveying distance exceeds 30m, it is easy to return wind, the productivity is low and unstable, and it is only suitable for shotcrete support of small roadways.

3, Rotor-type rotor jet machine has the advantages of large production capacity, long transmission distance, continuous and stable discharging, low feeding height, convenient operation, suitable for mechanized supporting operations, etc., and can be used for dry spraying, semi-wet spraying, wet spraying, etc. A variety of shotcrete methods is a widely used model.