Views:26 Author:Site Editor Publish Time: 2019-11-14 Origin:Site
Compared to dry shotcreting, wet shotcreting also has some disadvantages. When you want to buy a wet shotcrete machine, you need to know these factors.
· The discharge speed from the jet is considerably higher compared to the dry method, and therefore the compact effect is smaller and so the final consistency is better. It is not possible to apply more than 5 cm thick layers if spraying overhead. Any thicker layers should be sprayed one at a time.
· Further addition of a hardening agent in the spraying jet is difficult as the liquid hardening agents require a fairly high W/C due to pumpability. The wet mixture requires more concrete to reach the same strength compared to using the dry mixture. Usually, setting retarders or hardening agents or plastificators are needed to improve the pumpability in order to comply with the quality.
· Only a limited period of time is available between mixing and application of the wet concrete.
· It is not possible to interrupt the working process. In case of any longer delays, the entire system must be emptied, cleaned and filled up again before renewing the work.
· Another disadvantage is that more complex and more costly machinery including more robust transport pipes are required.