Admixtures and fibers for shotcrete in Japan
In recent years in Japan the following additives are increasingly being used for Shotcreting in tunnels: Accelerator for shotcreting based on calcium aluminate; dust control agent; and fiber. While dry mix shotcrete was predominantly used in Japan, accelerator of shotcrete based on inorganic salts contributed a great deal to the performance of shotcrete. However this type of accelerator is not so effective to wet mix which has been taking the place of dry mix in recent years. For wet mix shotcrete, accelerator for shotcrete based on Amorphous calcium aluminate is found to be quite effective in gaining sufficient early strength without aggravating long term strength. Practical performance in various cases is reported. A dust control agent for shotcreting is often used to improve working conditions in tunnels. This agent is reported to reduce a great deal of the dust generated in shotcreting operations. A variety of dust control agents are now available, of which constituents are cellulose epoxy , acrylic epoxy, polyvinyl alcohol etc. Use of fibers in shotcrete is also becoming popular in Japan to increase strength and toughness of the concrete. Not only steel fibers but also glass fibers are widely used. Recently more variety of materials such as PVA fiber acrylic and aramid fibers have been tested and some of them are being put into practical use, giving similar properties to shotcrete with steel fibers.
- OSTI ID:
- 483894
- Report Number(s):
- CONF-9506349-; TRN: IM9726%%287
- 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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