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C3 – Carbon Concrete Composite – From the largest construction research project to the most important association for carbon reinforced concrete construction. Carbon reinforced concrete is becoming increasingly used in practice: in new construction and in the field of retrofitting. Numerous companies, associations and institutions are working under the brand of C3 – Carbon Concrete Composite to make the use of carbon reinforced concrete technology easier, to exploit the numerous advantages of carbon reinforced concrete and thus to make a significant contribution to climate neutrality. This article describes the beginnings of the idea, which sounded absurd in the 1990s, and outlines the development phases from a construction research project to the most important association in the field of building with carbon reinforced concrete. [ABSTRACT FROM AUTHOR]

Examination of concrete samples with CFRP and GFRP reinforcement by X‐ray computed tomography and laminography – concrete samples with CFRP and GFRP reinforcement Non‐metallic reinforcements are already widely used in concrete construction today. Up to now, material testing has mainly been carried out under destructive conditions. As a consequence, the position of the reinforcement within the concrete matrix is determined by inspection and measurement of saw cut interfaces. Imaging procedures as X‐ray computed tomography (XCT) and laminography (XCL) enable the nondestructive evaluation and location of carbon and glass fiber reinforcements within the volume of a concrete structure platform. The concrete cover as well as the yarn cross‐section, spacing and the position of the reinforcement can be determined in the concrete matrix by XCT, the latter with a deviation of < 0.2 mm in comparison with the destructive control measurements of the previous method by means of a measuring microscope. A special combination of limited‐angle X‐ray computed tomography (LAT) followed by XCL has been shown to increase the detailed recognition of the reconstructed sectional images compared to the individual procedures. [ABSTRACT FROM AUTHOR]

Zur effizienten und seriellen Herstellung von Textilbetonplatten im Gießverfahren fehlten bis zum jetzigen Zeitpunkt geeignete Abstandhalter, mit denen eine sichere Fixierung der textilen Bewehrung in einer Schalung möglich ist. Das Abstandhaltersystem DistTEX eröffnet jedoch diese Möglichkeiten. Die Lage der textilen Bewehrung bleibt während des Gießprozesses erhalten. Die Handhabung und die Einflüsse auf die Eigenschaften von Textilbetonbauteilen mit diesem neuen Abstandhaltersystem wurden an der TU Dresden untersucht und ausgewertet. Die Abstandhalter überzeugten in ihrer Anwendung und ihren Eigenschaften. Es konnte keine Minderung der Tragfähigkeit festgestellt werden. Die visuellen Untersuchungen der Betonoberflächen ergaben, dass die verwendeten Abstandhalter weder unter Normbedingungen noch unter Temperaturschwankungen von bis zu 60 K negativen Einfluss haben. Bei der Überprüfung der Lage der textilen Bewehrung konnten nur leichte Abweichungen von der Solllage festgestellt werden. Textile Reinforced Concrete produced in casting process with Spacer Up to now, an efficient or serial fabrication of textile reinforced concrete slabs through casting was impossible due to the lack of spacers for fixing the textile reinforcement in a formwork. However, the spacer-system DistTEX makes this possible now. The position of the textile reinforcement remains the same during the casting process. The handling of textile reinforced parts with this new spacer-system and its influence on the properties were researched and analysed at TU Dresden. The spacer-system was convincing with regard to its application and properties. Apparently, the load-bearing capacity was not reduced. A visual analysis of the concrete surface did not reveal any negative influences of the applied spacer-system either under normal conditions or under temperature variation of up to 60 K. The position of the textile reinforcement proved to have drifted only slightly from the reference position. [ABSTRACT FROM AUTHOR]

Ein großer Teil der weltweit vorhandenen Silos ist über 50 Jahre alt und bedarf in den kommenden Jahren einer Erneuerung oder Sanierung. So war bei einem im Jahr 1962 erbauten Doppelkammersilo aus Spannbeton mit einem Fassungsvermögen von 20 000 t Zucker eine Rissinstandsetzung erforderlich. Im Rahmen einer Voruntersuchung wurde hierfür ein Vergleich möglicher Instandsetzungsverfahren durchgeführt. Im Ergebnis wurde die Verstärkung mit Textilbeton gewählt. Für die ca. 3 100 m2 große Sanierungsfläche wurden ca. 14 000 m2 textile Bewehrung sowie ca. 150 t Feinbeton verbaut. Crack repair of a sugar silo Worldwide, a great part of the existing silos is older than 50 years and require renovation in the coming years. For example, crack repair was necessary for a twin compartment silo, which is made of prestressed concrete and can hold up to 20 000 t of sugar, from 1962. In this context, a preliminary investigation was made with the aim of comparing the different possibilities for restoration. Eventually, strengthening through textile reinforced concrete was chosen. Approximately 14 000 m2 of textile reinforcement and 150 t of fine grained concrete were used for approximately 3 100 m2 restoration area. [ABSTRACT FROM AUTHOR]

In den vergangenen 15 Jahren lag im deutschen Bauwesen ein Forschungsschwerpunkt auf dem Verbundmaterial Textilbeton. 2011 endete die Finanzierung der durch die Deutsche Forschungsgemeinschaft (DFG) geförderten Sonderforschungsbereiche an der TU Dresden (SFB 528) und an der RWTH Aachen (SFB 532). Im Zuge dieser Forschungsarbeiten entstanden bereits erste Pilotbauwerke, die das hohe Potenzial von Textilbeton demonstrieren. Besonders im Bereich filigraner Neubauteile und der Verstärkung bestehender Tragwerke konnten mit dünnen Schichten aus Textilbeton unter Ausnutzung seiner hohen Zugtragfähigkeit Ansätze für eine wirtschaftliche Alternative zu konventionellen Bauweisen aufgezeigt werden. Um die Verbundwerkstoffe für ein breites Anwendungsfeld nutzbar zu machen, lag der Fokus in den vergangenen Jahren auf der anwendungsorientierten Forschung in Zusammenarbeit mit Firmen der Bauwirtschaft. So sind beispielsweise im Bereich der Fassadenelemente kleinformatige Platten aus Textilbeton heute bereits Stand der Technik. Auch für Brückenkonstruktionen, Tragwerksverstärkungen und großformatige Bauteile wie Balkonbodenplatten oder tragende Schalenkonstruktionen konnte die hohe Leistungsfähigkeit von Textilbeton ausgenutzt werden. Textile concrete - an overview of executed projects In Germany, a research focus was on the composite material textile reinforced concrete (TRC) in the last 15 years. In 2011 two Collaborative Research Centres (SFBs), SFB 528 at the TU Dresden and the SFB 532 at the RWTH Aachen, funded by the Deutsche Forschungsgemeinschaft (DFG) were successfully completed. Within the research projects, pilot buildings have already been developed to demonstrate the high potential of textile reinforced concrete. Particularly in the field of strengthening of existing structures and thin walled new components, thin constructions with a high tensile bearing capacity provide a cost-effective alternative to conventional construction methods. With the aim of applying the material in a wide range of fields, numerous different research projects were realised in collaboration with companies from the construction industry in the last years. For instance small-sized slabs made of textile reinforced concrete are already the state-of-the-art in the field of facade panels. Furthermore, the high effectiveness of textile reinforced concrete could be shown for the strengthening of existing structures, bridge constructions and large-sized components such as balcony floor slabs or bearing shell structures. [ABSTRACT FROM AUTHOR]

Abstract: The use of textile reinforced concrete (TRC) is a very effective method for strengthening reinforced concrete (RC) constructions. Within the Collaborative Research Centre 528 of the Technische Universität Dresden (TU Dresden) vast research on TRC was carried out, so as to examine the use of TRC for subsequently strengthening the bending load capacity of existing concrete or reinforced concrete components. As a rule, the experimental research was done at small format reinforced concrete slabs with span widths of 1.60m and slab thicknesses of 0.10m strengthened with TRC. At the same time calculation models were developed to predict the maximum bending load capacity of the reinforced components amongst others. This article describes the experimental and theoretical research reassessing the assignability of the results gained until now to large scale reinforced concrete slabs with a span width of 6.75m and slab thickness of 0.23m. By using textile high-performance carbon reinforcements based on so-called heavy-tow-yarns very high strengthening levels can be realized. The results show significant load bearing capacity increases compared to unreinforced reference slabs. Thus the safe use of bending reinforcements consisting of TRC could be demonstrated for components with even large span widths and high reinforcement degrees. Simultaneously a distinct decrease of deflection with growing reinforcement degree was verified at a comparable load level. Calculation results of the presented simplified calculation model for the estimated bending measurement are consistent with the load carrying capacities determined experimentally. Using the finite element method (FEM) not only the load bearing capacities but also the deformations were calculable keenly. [Copyright &y& Elsevier]

Rebars made of carbon fibres for the use in civil engineering: part 2: bond behaviour – bond tests with different carbon rebars Carbon reinforced concrete is becoming more and more accepted in the building industry. The use of mat carbon reinforcement is well researched in regard of the tensile and the bond behaviour. But there is still a considerable need for research in the case of carbon fibre rods and here in particular on the bond behaviour of the rods in concrete. For this reason, 8 various carbon rods with different surface profiles were evaluated in bond tests. The results were compared with the bond behavior of a conventional steel rod. Based on the results, a preferred rod variant was recommended, An in‐depth examination of these will be part of a further publication. [ABSTRACT FROM AUTHOR]

At the Institute of Concrete Structures, Technische Universität Dresden, a new precast ceiling system comprised of an arch and a beam at each longitudinal edge was investigated. The innovative composite material carbon reinforced concrete allows thereby a fresh way of thinking for civil engineering with lightweight constructions but still high bearing capacity. This variation of a beam has only straight rebars as main reinforcement. Four prototypes with a length of 4.50 m were produced and tested at Otto–Mohr‐Laboratory of TU Dresden. Except of the supports, the structure has a thickness between 40 and 45 mm, so a reduction of the dead load up to 70.0% compared to a usual rectangular cross section made of common steel reinforcement and the same concrete could be achieved. The experimental ultimate loads of the first three tested elements were thereby higher than the calculated ultimate load of the common reinforced concrete structure. [ABSTRACT FROM AUTHOR]

Abstract: Reinforcement made of carbon fiber reinforced concrete In the research project C3 – Carbon Concrete Composite new reinforcement systems made of carbon for concrete construction are developed. In that case, mesh‐like and bar‐shaped reinforcements are examined. Until now, these carbon reinforcements predominantly contain a plastic matrix that combines thousands of carbon filaments into one cross section. Scientists of the HTW Dresden and the TU Dresden are currently pursuing an approach to replace this plastic matrix with a mineral matrix to further improve the properties of the carbon reinforcement. In this paper, the basic principle of this new type of reinforcement for concrete construction as well as associated tests are presented. This should give an impulse for further research in this field. [ABSTRACT FROM AUTHOR]

Parking garage buildings are usually comprised of steel reinforced concrete (RC) slabs. Unfortunately, there are often cases of damage caused by the high exposure to corrosive chemicals. To prevent corrosion of the reinforcement, especially the ceilings must be coated with expensive protection systems. Due to the not‐corrosive nature of carbon fibers, carbon RC is a perfect solution for those structures. But before using carbon RC for parking slabs, the problem of the end anchorage of the reinforcement by short‐end anchorage lengths had to be solved. Therefore, a new anchorage method for carbon RC is described in detail in this publication. A large‐scale test had been conducted to show the potential of carbon RC for parking slabs and to prove the ability of the developed new‐end anchorage method. Also, an analytical recalculation of the large‐scale test is presented. [ABSTRACT FROM AUTHOR]

Drywall system made of carbon concrete composite With reference to recent developments of carbon concrete composite the question arises: 'Which fields are suitable to extend the application of carbon concrete composite to?' The following publication shows possible applications of carbon concrete composite for drywall systems. A definition of terms is followed by a description of drywall systems in general. The use of carbon concrete composite in this field derives from that section. First promising results are presented following calculations, experiments and practical tests. [ABSTRACT FROM AUTHOR]

Mit der zunehmenden Verbreitung des Textilbetons wird die Standardisierung von Versuchen zur Ermittlung der Materialkennwerte immer bedeutsamer. Im Rahmen der Grundlagenforschung sowie in Praxisprojekten und Verfahren zur Erteilung zahlreicher Zustimmungen im Einzelfall (ZiE) bzw. zur Erlangung einer allgemeinen bauaufsichtlichen Zulassung (abZ) haben sich wesentliche Kennwerte inklusive der zugehörigen experimentellen Untersuchungen herauskristallisiert. Die Veröffentlichung gibt hierzu einen aktuellen Überblick. Textile Reinforced Concrete - Overview of standard test methods Due to the fact that textile reinforced concrete is applied increasingly often, the development of standardized testing methods for the determination of material data is steadily gaining importance. The significant data and the corresponding experimental tests have already crystallized in the course of basic research and in practice projects as well as during procedures for the granting of numerous approvals for individual cases or general technical approvals. This publication offers a current overview of this topic. [ABSTRACT FROM AUTHOR]

Flexuaral load experiments on RC slabs with additional textile strengthening are presented in this work. RC slabs of 3 to 7 m in length are subsequently strengthened with a layer of textile reinforced concrete (TRC) and loaded until rupture in four-pointflexural- tests. Their load bearing capacities are compared to the reference slabs without textile strengthening reinforcement. Varying the number of textile reinforcement layers, it is shown to what extent the flexural load bearing capacity of RC slabs can be increased by means of the carbon textile reinforcement. The strengthening effect of TRC is proved. The experimental results are compared to the ones calculated afore. The good agreement of the experimental and calculated results validates the design concept of TRC strengthening. [ABSTRACT FROM AUTHOR]