Spray cement and process technology with regard to state-of-the-art shotcrete

The Present paper describes the state-of-the-art spray cement and process technology with regard to sprayed concrete as a support measure in tunnelling, as well as the implications for human beings and the environment. In particular, the reaction mechanisms in terms of initial setting and hardening kinetics of the different material systems will be described and the essential characteristics be Pointed out. In addition, the definition of an ecologically desirable shotcrete will be presented and the current environmental situation will be summed vp based on a few prominent examples. Moreover, the economic recycling law and its significance For the use of construction materials in underground supply and traffic routes will be discussed. Finally the currently common tender specifications for shotcrete will be reviewed critically, and alternative approaches be pointed out.