Innovations in shotcrete technology
- Innsbruck Univ. (Austria). Inst. for Construction Materials and Material Testing
Environmental considerations and special technological objectives require changes in the composition and spraying technique of shotcrete on Central European construction sites. These requirements can only be fulfilled by changing the conception of the mix design and the methodology. The following aims are to be achieved by new technologies: reduction of the leaching behavior of the applied shotcrete; reduction of rebound and dust formation during the placing of the shotcrete; improved deformation behavior without reduction of strength properties; and integration of the shotcrete as a structural element of the tunnel lining and, if feasible, substitution of the inner lining concrete by shotcrete. New accelerators on alkali-free basis in powder form have been refined to such an extent that they can be used successfully. When used in combination with other concrete admixtures, this alkali-free accelerator significantly reduces leaching rates, while there is no significant decrease in strength as compared to base concrete. When placing the shotcrete, there is both less dust formation and less rebound. Apart from the development of this new generation of accelerators in combination with rebound and dust reducers, there are also special binders on the market that manage without accelerators. This requires a new procedure (batching and mixing technology for the dry-mix method) so that natural moist aggregates can be used. The basic idea is to mix binder and moist aggregate shortly before or in the shotcrete machine. The binder itself should not react with the moist aggregate in the first stage of the mixing process. Only after having been conveyed to the discharge nozzle it should harden quickly when water is added at the nozzle.
- OSTI ID:
- 483896
- Report Number(s):
- CONF-9506349-; TRN: IM9726%%289
- Resource Relation:
- Conference: 7. conference on shotcrete for underground support, Telfs (Austria), 11-15 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of Shotcrete for underground support 7: Proceedings; Klapperich, H. [ed.] [DMT, Essen (Germany)]; Poettler, R. [ed.] [Kling Consult, Krumbach (Germany)]; Willocq, J. [ed.] [Lafarge Fondu International, Paris (France)]; PB: 325 p.
- Country of Publication:
- United States
- Language:
- English
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