Abriss und Neubau bestehender Bauwerke sind mit einem hohen Ressourcenverbrauch und erheblichen CO2-Emissionen verbunden. Vor diesem Hintergrund gewinnt der Erhalt vorhandener Bausubstanz durch gezielte Verstärkung zunehmend an Bedeutung. Carbonbeton eröffnet dabei eine neue Möglichkeit für das nachhaltige Bauen im Bestand: Der korrosionsbeständige und leistungsfähige Verbundwerkstoff ermöglicht dünne, leichte und ressourcenschonende Verstärkungsschichten für bestehende Stahlbetonbauteile. Der Beitrag gibt einen Überblick über die Grundlagen des CARBOrefit-Verfahrens zur Verstärkung mit Carbonbeton einschließlich der wesentlichen Ausführungsschritte und zeigt anhand ausgewählter Praxisbeispiele das Anwendungspotenzial der Technologie auf.
Thin, durable, load-bearing: reinforcement with carbon concrete
The preservation of existing building stock is a key approach to conserving resources and reducing construction-related environmental impacts, and is regarded as a significant contribution to achieving climate targets. Against the backdrop of ageing buildings and infrastructure, as well as growing demands for resource conservation and sustainability, innovative methods for preserving and retrofitting existing building stock are therefore increasingly coming into focus. In this context, carbon concrete represents a promising approach, which is applied, amongst other things, using the CARBOrefit process and opens up new possibilities for the retrofitting of existing structures. Carbon concrete is a composite material consisting of a concrete matrix and non-metallic carbon reinforcement. The load-bearing principle is essentially the same as that of reinforced concrete and also shares similarities with conventional shotcrete reinforcement: within the reinforcement layer, the carbon fibre reinforcement absorbs the tensile forces, whilst the concrete ensures the transfer of composite forces to the existing concrete. The key difference compared to steel reinforcement lies in the corrosion resistance and high performance of the carbon fibre mesh. This allows the required concrete cover to be significantly reduced. This increases the material efficiency and durability of the material, enabling savings in both materials and emissions compared with steel-reinforced layers. When retrofitting existing structures, the total layer thickness of a carbon concrete reinforcement is usually between 10 mm and 20 mm. Whilst conventional shotcrete reinforcement requires a layer thickness of around 7 cm, the CARBOrefit process enables a comparable level of reinforcement to be achieved with a layer thickness of just around 1 cm. This allows for the production of thin, lightweight yet high-performance reinforcement layers.