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Shotcrete has become a common practice for both new construction and repair and renovation. Concrete can be sprayed by one of two processes – one is “dry shotcrete” or “gunite” in which case dry material floats to the end of the hose via compressed air, then water is added at the nozzle. The second process “wet shotcrete” is the process whereby the material is mixed with water, added to the pump, then conveyed in a wet slug through the pipeline until it reaches the nozzle where air is then added to give the material velocity so it will stick to the wall or overhead.
The difference between dry and wet shotcrete:
Dry sprayed concrete mixes cement, sand, stone mixture and powdered accelerator in a certain proportion and mixes them evenly. In a loose, dry and suspended state, dry shotcrete machine is used and compressed air is used as power, through the feeding tube to the nozzle, mixed with a certain amount of pressure water, and it becomes concrete with a relatively small water ash and sprayed onto the sprayed surface. If a special quick-setting anchor is used for spraying cement, the accelerator may not be used. The process is simple, easy to operate, and has a long conveying distance (up to 150-200m on average), but the large dust and high rebound rate are its fatal weaknesses.
Wet spraying is a new sprayed concrete technology developed for the problems of dry spraying, such as large dust, large rebound rate, and insufficient hydration. The obvious feature of wet shotcrete is that the concrete mixture is added with sufficient mixing water before entering the shotcrete machine or in the jetting machine, mixed evenly, and then sent to the nozzle through the feeding hose to be sprayed onto the sprayed surface. Therefore, the water-cement ratio of concrete can be accurately controlled, which is beneficial to the hydration of water and cement. Therefore, the dust is small, the rebound is less, the homogeneity of the concrete is good, and the strength is easy to ensure, but the water consumption is greater than that of dry spraying. Compared with dry shotcrete machine, it is more complicated and costly. Wet shotcrete machine is the main equipment for wet spraying.
Gengli machinery is the excellent manufacturer of shotcrete machine with more than twenty years of production experience. The products include dry mix shotcrete machine, wet mix shotcrete machine, Truck-mounted Shotcrete Machine and Truck-mounted Robot Shotcrete Machine. If you are interested in our shotcrete machine, please contact us freely.