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2015SpringShotcreteEMag

Industry News Alpbach Conference 2015 The 11th Shotcrete Conference took place in the Alpbach Conference Centre from January 29 to 30, 2015. Organizer Professor Wolfgang Kusterle welcomed approximately 260 guests. Participants value these now-traditional shotcrete con- ferences in Alpbach, Austria, for their interesting presentations as well as for the relaxed ambience. Professor Jozef Jasiczak started the sequence of presenta- tions with the story of Warsaw Museum of the Polish Jews. The structure of the museum included several very large multi- axially curved wall panels made of dry-mix shotcrete. A second presentation on the versatility of shotcrete for architecturally challenging projects showcased the construction of shotcrete walls which resemble natural stone masonry. In the latter presentation, the audience learned about textile reinforcement of shotcrete, which is easier to embed than traditional reinforcing bar, requires less cover, and enables a Fig. 1: Prof. Kusterle welcomes 260 guests at the higher degree of reinforcement. Details of shear reinforcement “Spritzbeton-Tagung 2015,” Congress Centrum Alpbach of long beams and protective layers for hydraulic structures (Photo: Kusterle) were the subjects of two presentations. Where shotcrete requires both high resistance to fire and explosions, reinforcement with extremely high fiber contents is required. One presentation described that such shotcrete can only be pumped and sprayed if batched with uncommonly high air contents. Two presentations, from Canada and England, discussed heavily reinforced structural shotcrete, with rein- forcing bar diameters to approximately 1 in. (30 mm). Calcite deposits in the drainage systems of road and rail tunnels have become a significant concern in Europe. One reason for such precipitations may be a high content of clinker in the mixture. Two presentations explained the mechanisms causing such deposits and discussed methods to control them. In the session on testing, a presentation on various methods for the determination of early strength development reminded Fig. 2: Curving wall panels of tinted shotcrete in the the audience of the limits and errors accompanying many of the entrance area of the Museum of the History of Polish Jews, test methods in use. A novel miniature shotcrete test device for Warsaw (Photo: Josef Jasiczak, Poznan University of Technology) the production and early-age evaluation of shotcrete mortars was introduced. Its intended use is the rapid and economical study of admixture-cement compatibility issues. An important refresher on correct nozzle direction, nozzle distance, and material velocity presented information on optimum spray conditions. Many infrastructure tunnels have seen long years of service and require significant maintenance. Repair and maintenance may greatly extend the service life of tunnels if issues of per- colation of acidic ground water, deicer salt exposure, frost attack, and surface contamination can be addressed thoroughly. Two related presentations offered details about cathodic cor- rosion protection for the Rendsburg tunnel and the use of white shotcrete for the Agnesberg tunnel. Several presentations also analyzed single-shell tunnel walls and the state-of-the-art in waterproofing technology. A presentation on the different and sometimes incompatible or ill-defined code requirements affecting shotcrete and spray-applied mortars illuminated the Fig. 3: Miniature nozzle of a laboratory mortar spraying and formal aspect of shotcreting. testing device (Photo: Kusterle) 60 Shotcrete • Spring 2015


2015SpringShotcreteEMag
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