Untersuchungen an einer vier Jahre alten Schutzschicht aus textilbewehrtem Spritzbeton am Wehr Horkheim

摘要

Im September 2010 wurden im Rahmen eines gemeinsamen Forschungsprojekts zwischen der Bundesanstalt für Wasserbau (BAW) und dem Institut für Bauforschung der RWTH Aachen University (ibac) acht Probeflächen aus textilbewehrtem Spritzbeton mit unterschiedlichen Aufbauten an zwei Pfeilern des Wehrs Horkheim angelegt. Für diese Pilotanwendung kamen ein S-A3 Beton der Fa. StoCretec sowie technische Textilien aus AR-Glas oder Carbon zur Anwendung. Die technischen Textilien wurden im Rahmen der Textilproduktion mit Styrol-Butadien-Kautschuk (SBR) und mit Epoxidharz (EP), zur Anwendung. Bei der Herstellung der Probeflächen wurde am Bauwerk ein System für ein Riss- und Temperaturmonitoring installiert [1]. Der Beitrag stellt die Ergebnisse der Bauwerksuntersuchungen knapp vier Jahre nach der Herstellung der Probeflächen vor. Sie zeigen, dass keine nennenswerten Risse in den Schutzschichten vorhanden sind, eine ausreichende Haftung zwischen Schutzschicht und Beton gegeben ist und auch in der Wasserwechselzone keine Schäden erkennbar sind.%Eight sample areas of textile-reinforced sprayed concrete were applied to two piers of the Horkheim weir in September 2010 as part of a joint research project between the BAW (Federal Waterways Engineering and Research Institute) and the Institute for Building Research at Aachen University of Technology (ibac). An S-A3 mortar from StoCretec and industrial textiles made from AR glass and carbon, polymer-impregnated with styrene-butadiene rubber (SBR) and with epoxy resin (EP), were used for this pilot application. A system for monitoring cracks and temperature was installed during the production of the sample areas. The article presents the results of the examination of the structure almost four years after the production of the sample areas. The findings derived from measurements and observations carried out over a period of about four years can be summarized as follows: 1. The average layer thickness of 40 mm complied with the maximum permissible layer thickness of 60 mm specified in ZTV-W LB 219 for surface application of unreinforced and unanchored layers of sprayed concrete. 2. Even after a service life of almost four years an adhesive tensile strength of the textile-reinforced protective layer comparable with Class S-A3 was found with sample surfaces 2,3,6 and 8. The other sample surfaces reached adhesive tensile strengths complying with Class S-A2. 3. On pier 3 of the Horkheim weir the maximum changes in crack width in the substrate (old concrete) lay between approximately 0.18 mm and 0.28 mm. 4. Comparison of the sample areas shows that without textile reinforcement it is not possible under the given conditions to prevent the cracks present in the substrate from breaking through. 5. All the crack widths detected in the textile-reinforced sprayed concrete layers during the examination were, as planned, smaller than 0.1 mm. 6. The testing over a period of years in the pilot project under real conditions has shown the significant advantages of textile-reinforced protective layers. These new types of material offer an attractive alternative to the former protection and repair procedures and materials, especially with respect to the durability of the protective measures.