Today's challenges comprise climate change, urbanization, and demographic change. The building industry is of major technical and economic importance for these subjects. Due to the versatility, structural concrete is the major applied material in building industry. The associated cement production contributes significantly to the CO2 emissions. Hence, new technologies and planning methods as well as production and recycling techniques have to be developed to account for a fast changing world and to reduce the carbon footprint. High‐performance materials, such as textile reinforced concrete, in combination with new construction methods and conceptual designs, can reduce the material usage significantly. In this paper, new construction methods as well as conceptual designs are proposed, which result in economic structural members.
Ein typisches Anwendungsfeld für gefugte Betonflächen sind Betonfahrbahnen. Diese sind hohen Beanspruchungen aus dem Verkehrsaufkommen und extremen Witterungsbedingungen ausgesetzt. Um wilde Risse aus daraus entstehenden Zwangsspannungen zu verhindern, werden in der Regel Querscheinfugen eingebracht. Diese stellen jedoch zugleich eine Schwachstelle im Beton dar, sodass eine kontinuierliche Instandhaltung und Wartung notwendig werden. Eine ökologisch und ökonomisch sinnvolle Alternative zur Erneuerung der gesamten Betondecke ist die Sanierung der Betonfahrbahn mithilfe einer fugenlosen und zugleich dünnen Deckschicht aus Carbonbeton. Eine Trennung des Verbunds zwischen Alt‐ und Carbonbeton im Bereich der Querscheinfuge gewährleistet die Verteilung entstehender Risse und die Reduzierung der Einzelrissbreiten durch multiple Rissbildung. Flüssigkeiten können so weniger tief in den Beton eindringen und schaden weder dem Altbeton noch der korrosionsresistenten Carbonbewehrung.
Zusammenfassung Für die Etablierung von Carbonbeton in der industriellen Praxis sind Prüfverfahren zur reproduzierbaren Bestimmung der mechanischen Kennwerte textiler Bewehrungsstrukturen essentiell, insbesondere der Zugfestigkeit. Zu diesem Zweck wurde im Rahmen des Forschungsvorhabens C³-V1.2 ein neuartiges Prüfverfahren entwickelt und qualifiziert. Mit diesem Verfahren können Carbonfaserstränge aus flexiblen, steifen und bedingt biegbaren Bewehrungsgelegen hinsichtlich ihrer Zugfestigkeit mit geringem Präparationsaufwand und reproduzierbar charakterisiert werden.
Deck caps of bridges—in Germany shortly known as “bridge caps”—are usually made of steel reinforced concrete to form the anchoring area for the guardrail of bridge deck edges on existing cantilever slabs. Combined with protective devices, the outside arranged deck caps provide safety against lateral breaking or crashes of vehicles. Due to their exposed position in the cross section of bridges and the particularly intensive stresses, the deck caps are considered as wear parts and have to be renewed several times during the service life of a bridge. The decisive factor here is the discrepancy between the frost resistance of the concrete and the crack width restriction. On the one hand, only very small cracks (<0.2 mm) can be accepted to prevent corrosion of the rebars under the strong exposure of these elements. To confine crack widths without applying an excessively high degree of reinforcement, a low concrete compressive strength is advantageous. On the other hand, a sufficient frost resistance requires a correspondingly high compressive strength. With carbon reinforcement, these contrary points could be defused and simultaneously the needed durability could be provided. Therefore, slightly modified deck cap concretes combined with a carbon reinforcement mesh were tested to examine the bond behavior with and without freeze–thaw attack. To prove the characteristics of this combined system, the crack formation and crack distribution were investigated experimentally. The test results were compared to calculated values from a mathematically tool to be able to develop different reinforcement concepts in future that can ensure an optimized crack formation and crack width for deck caps.
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