Low rebound sprayed concrete "Multi Effect method"

Sprayed concrete is concrete that is sprayed directly onto the ground after tunnel excavation to serve as a support material. When concrete is sprayed, bouncing (rebound) occurs. So far, various methods have been developed and put into practical use for the purpose of reducing the amount of rebound. For example, there is a method to increase the amount of powder such as cement or admixture (fly ash or ground granulated blast furnace slag). There are also methods to increase the viscosity of concrete and to add thickeners directly by using special machines. However, these methods require additional equipment separately, which increases the cost of materials and labor during construction, thus increasing construction costs.
This "Multi Effect method" can increase the viscosity of sprayed concrete and reduce the amount of rebound only by adding a special admixture, instead of the admixture required during concrete production, without changing the conventional mix proportioning and construction machinery, etc.