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The potential of textile-reinforced concrete is broad: it can be used in new structures and in the retrofitting of existing structural components. Designing textile-reinforced concrete requires knowledge about the mechanical properties of different textile types. To this, a standardised tensile test for fibre strands was used. The test aims to statistically characterise two material properties needed in design: ultimate tensile strength and the modulus of elasticity. To this, the influence of length and number of fibre strands were evaluated. The results show that the ultimate tensile strength can be statistically modelled by a Gumbel distribution and the modulus of elasticity can be characterised by a Normal distribution. These findings can be used to derive appropriate partial safety factors for the design value of tensile strength using probabilistic methods, or to directly determine the failure probability of textile-reinforced concrete components. [ABSTRACT FROM AUTHOR]

Numerous concrete monuments built in the High Modern Era (turn of the 20th century until the 1970s) must now be repaired for preservation. Traditional concrete repair according to current guidelines involves considerable material removal, changing the appearance of the existing structure. With a combination of the material properties of high-/ultra-high-performance concrete (HPC/UHPC) with its dense microstructure and corrosion-free textile reinforcement (carbon and basalt), a high-performance mortar repair system can be developed. Such a system allows for concrete repairs with minimal material loss by using very thin layers that are durable and do not change the architectural character of the repaired monument. For the investigation of the load-bearing behaviour of a structural repair system using textile-reinforced, high-performance mortar, 20 mm thick slabs were produced and mechanically characterized. In the next step, the proposed repair system was applied to 70 mm thick old concrete slabs. The results show that a high surface tensile strength of 2.9 MPa was obtained. In a further step, the system will be applied to concrete pillars of transmission tower in Berus, adapted in terms of colour and structure and installed for long-term monitoring. [ABSTRACT FROM AUTHOR]

In this article, a partial selection of experiments on enhancing the impact resistance of structural components with non-metallic, textile-reinforced concrete is discussed. The focus is on the experimental investigations in which the impact resistance of thin, textile-reinforced concrete plates is characterized. The article discusses the materials, fabrics and test setup used. For the experimental work, a drop tower from the Otto Mohr Laboratory, which belongs to the Technische Universtät Dresden, was used. Furthermore, the experimental results are presented and evaluated using different methods. Based on the collected data, a suitable approach to determining the perforation velocity of an impactor through the investigated thin, textile-reinforced concrete plates is shown.

This paper describes a work that examines a new solution to the problem that arises from the relatively high amount of transverse reinforcement required in HSC columns. It presents an alternative to common transverse steel reinforcement, a dual system comprising steel ties and a carbon-fiber mesh (CFM) applied internally together with steel ties. The behavior of the proposed system was examined in this work in a series of twelve laboratory tests of circular stub column specimens. The experiments performed in this work focused on the columns’ load and displacement capacities. The tests were planned with the aid of an analytical model that was originally developed for a hybrid system of external fiber-reinforced polymer (FRP) sheets and internal steel, and was adapted for the current system. An analysis of the results shows that for a given amount of conventional transverse steel, the application of the carbon-fiber meshes adds efficiency to the rebar confinement system, in terms of both the load bearing capacity and the ductility, and for specimens with the hybrid confinement system, the higher the carbon fiber amount the larger the ductility improvement. Furthermore, fair to good agreement was observed between the model and the measured stress–strain curves, especially those of the peak stresses. Based on the above findings and the added benefit of fire resistance, the hybrid method appears to be promising for confining HSC columns.

This research aimed to investigate the energy properties of buildings made of textile-reinforced concrete (TRC) sandwich panels in various humidity-climatic zones. Two configurations of sandwich panel are considered: conventional and advanced. The conventional sandwich panel consists of inner and outer 75 mm thick reinforced concrete layers with separated by a layer of insulation made of extruded 50 mm thick foam polystyrene (XPS) slabs. In the advanced design, due to the use of TRC, the thickness of interior and exterior structural layers is reduced to 40 mm (while maintaining strength), and the thickness of the heat-insulating layer increased to 120 mm. Glass plastic connectors of 10 mm diameter located in nodes of a square grid connect the structural layers. The authors applied an analytical method of research to buildings’ energy performance made of TRC sandwich panels based on the investigation of heat and moisture transfer processes in continuous heterogeneous media and analysis of energy indicators of buildings. For the purposes of this research, the element-by-element and complex assessment of building thermal protection was performed. Based on the results of this research, the main thermal advantages of these facade systems are identified. Building component thermal resistance is increased in multiple humidity-climatic zones, providing a high thermal protection level in winter compared to conventional facade systems. Building component heat absorption is increased by 34.4% (compared to conventional facade systems), excluding the risk of overheating of premises in summer. The risks of moisture condensation and deterioration of hydrothermal-protective properties of building components are minimized. The use of TRC sandwich panels allows reducing total heat loss through the building envelope by 26.5%. Simultaneously, the building’s specific thermal characteristic is decreased by 16.7%, and the energy-saving class increases to high levels. Construction with advanced facade systems, when the precast sandwich panels with structural layers from textile-reinforced concrete are used, extends the creative boundaries of architecture and allows you to solve the current problem of improving the architectural environment’s quality and conserve energy for future generations.

The most popular crash barriers made so far are made up of steel-reinforced concrete (RC), which has high flexural rigidity but poor energy absorption. Consequently, when a vehicle collides with such crash barrier, the vehicle is seriously damaged and occupants may be fatally injured due to the severe impact of the collision. Hence, in order to enhance the safety of road users, a pre-fabricated textile-reinforced concrete (TRC) crash barrier prototype is developed using glass and basalt textile as reinforcement. The experimental investigations are carried out on both glass and basalt TRC crash barrier at the laboratory level under impact load to study the level of impact and deceleration rate. The performance of TRC crash barriers are also compared with RC crash barriers of equivalent calibrated reinforcement ratio. The lesser impact force and the lower rate of deceleration and higher energy absorption characteristics were experienced during the impact test for TRC crash barriers when compared to that of conventional RC barrier. Present study indicates that the application of TRC in crash barriers can improve the safety of the occupants and reduces damages to the impacting vehicles. [ABSTRACT FROM AUTHOR]

Textile-reinforced concrete (TRC) is a form of reinforced concrete, where conventional reinforcement is replaced with textiles or fibers. The high tenacity of the textile fibers results in flexible and durable concrete structures. The literature has been limited to TRC applications in retrofitting and nonstructural applications. Therefore, this article attempts to detangle the progressive research direction on the usage of TRC as a structural member. For this, (i) a bibliometric study using scientometrics analysis to visualize the keyword network, and (ii) qualitative discussions on identified research areas were performed. The literature was categorized into four main research areas, namely material properties of TRC, composite behavior of TRC, bond-slip relations, and TRC applications as structural elements. In addition, the advantages and disadvantages in the usage of TRC as a structural member are discussed in association with the identified research areas. Furthermore, the article proposes future directions to reinforce the research on the usage of TRC as a structural element. [ABSTRACT FROM AUTHOR]

This paper will present the shear behavior of the corroded stirrups reinforced concrete (RC) beams strengthened with textile reinforced concrete (TRC). The shear resistance contributions from the corroded RC beams and carbon TRC at various volume ratios were carefully examined. Eighteen beams were tested, including twelve subjected by an electrochemically accelerated aging technique for 60 and 90 days to obtain the theoretical mass loss in their stirrups of 10% and 20%, respectively. The stirrups were locally corroded in the shear span. After the corrosion accelerating treatment, corrosion cracks on concrete surfaces were marked, and their widths were measured to observe their distributions. A three-point bending test was applied to obtain the shear performances of the corroded beams subjected to the monotonic and repeated loading. Eight corroded RC beams were strengthened using 2 and 3 U-wrap layers of bidirectional carbon textile. The shear behavior will be discussed, including the ultimate capacity, failure mode, load-deflection, load–strain relationship, and crack distributions. Compared to the controlled specimens, the averaged shear strength of corroded specimens decreased by 16.08% and 25.34%, corresponding to the degree of corrosion ranging from 12.3% to 23.6%. The experimental results also demonstrate that the shear capacities of the corroded RC beams strengthened with carbon TRC had been improved 60.6% compared to the severely corroded controlled specimens.

This paper presents investigations on the tensile behavior of several textile-reinforced concrete (TRC) material compositions after fire exposure. First, experimental investigations are presented, aiming to provide insights into the thermomechanical performance of fire-exposed TRC, and data that can be used for the development and implementation of analytical or numerical models to design fire-exposed TRC elements. The applicability of the Aveston–Cooper–Kelly (ACK) theory is assessed for ambient and increased temperatures. TRC specimens with various cases of reinforcement (carbon or glass fibers, uncoated or coated textiles, low or high fiber volume fraction) were manufactured and subjected to temperatures reaching 700°C. The residual tensile capacity of the exposed specimens is discussed, focusing on the effect of the varying reinforcement. It is verified that the use of uncoated carbon fibers is the most promising solution for maintaining the residual capacity after fire exposure. Finally, it is concluded that the ACK predictions are reliable for TRC specimens with good bond conditions and when adopting a representative thermal degradation law for the reinforcement. [ABSTRACT FROM AUTHOR]

Textile-reinforced concrete is currently most frequently used for non-load–bearing structures, but there is a vision for also using it in load–bearing construction elements. In recent years, this construction material has been subjected to detailed examination. Different combinations of materials for potential use in textile-reinforced concrete have been described. These differ in the type of concrete mix and the composition of the textile reinforcement. The aim of this work is to test the application of a specific textile-reinforced concrete, consisting of high-performance concrete, textile reinforcement from carbon fibers and its epoxy resin matrix, at an elevated temperature. The combination of these materials makes it possible to produce subtle load–bearing structures with excellent mechanical properties. The critical issue is the behavior of these structures when exposed to fire. A series of medium-scale fire condition experiments were carried out with a temperature load based on the ISO 834 curve, followed up by mechanical tests. The aim of these experiments was to describe critical areas of textile-reinforced concrete in fire and to propose possible solutions. In an indicative fire experiment, experimental samples displayed massive spall of concrete layers, and interaction between materials was lost due to the low temperature resistance of the epoxy resin. Concurrently, the optimal quantity of polypropylene fibers was experimentally determined. This paper presents an experimental demonstration of the problematic aspects of textile-reinforced concrete and subsequent recommendations for future work with practical application in the design of load–bearing structures. [ABSTRACT FROM AUTHOR]

This paper discusses the state of the art in research on the use of textile-reinforced concretes in structural maintenance. Textile-reinforced concretes can be used in structural maintenance for various purposes, including the sealing and protection of the existing building structures, as well as for the strengthening of structures. The first-mentioned aspects are explained in this paper on the basis of example applications. A special focus is placed on the maintenance of heritage-protected structures. The development, characterization, and testing of a textile-reinforced concrete system for a heritage-protected structure are presented. Examples of the application of textile-reinforced concrete for strengthening highway pavements and masonry are also given. In particular, the possibility of adapting the textile-reinforced concrete repair material to the needs of the individual building is one advantage of this composite material.

Textile-reinforced concrete (TRC) is a promising composite material with enormous potential in structural applications because it offers the possibility to construct slender, lightweight, and robust elements. However, despite the good heat resistance of the inorganic matrices and the well-established knowledge on the high-temperature performance of the commonly used fibrous reinforcements, their application in TRC elements with very small thicknesses makes their effectiveness against thermal loads questionable. This paper presents a state-of-the-art review on the thermomechanical behavior of TRC, focusing on its mechanical performance both during and after exposure to high temperatures. The available knowledge from experimental investigations where TRC has been tested in thermomechanical conditions as a standalone material is compiled, and the results are compared. This comparative study identifies the key parameters that determine the mechanical response of TRC to increased temperatures, being the surface treatment of the textiles and the combination of thermal and mechanical loads. It is concluded that the uncoated carbon fibers are the most promising solution for a fire-safe TRC application. However, the knowledge gaps are still large, mainly due to the inconsistency of the testing methods and the stochastic behavior of phenomena related to heat treatment (such as spalling). [ABSTRACT FROM AUTHOR]

Fibre-reinforced polymers (FRPs) and textile-reinforced concretes (TRCs) are becoming increasingly common solutions for strengthening masonry walls. This study focuses on different approaches for modelling the behaviour of hollow concrete block masonry walls strengthened with FRPs and a TRC subjected to in-plane loading. Specifically, the masonry is modelled using the heterogeneous approach, wherein the damage post-peak softening behaviours of both bricks and mortar are considered, as this approach is appropriate for material and structure scales. To model the FRP/TRC-reinforced masonry walls, the reinforcements (FRPs/TRC) are perfectly connected to the substrate. Although the homogeneous approach is proposed to model the FRPs with linear elastic behaviour and is shown to be appropriate for modelling the FRP-reinforced masonry walls, the TRC is modelled using the heterogeneous approach, allowing for the real contribution of the filaments to be expressed through an 'efficiency factor'. The numerical results show that this factor has a significant influence on the behaviour of the TRC and therefore, on the overall behaviour of the TRC-reinforced walls. However, the 'efficiency factor' of the TRC sample is significantly higher than that of the TRC in the strengthened wall. This result confirms that the choice of the heterogeneous approach to model the TRC in our case is appropriate. Moreover, it verifies that it is impossible to transpose this global factor from the material scale (uniaxial tensile stress) to the structure scale when the application target is a masonry wall (multi-axiality, and therefore, complexity of the stress). Consequently, the constitutive laws of the TRC composite obtained through only direct uniaxial tensile characterization procedures are insufficient to enable a suitable restitution of the overall behaviour of the masonry reinforced with the TRC. In addition, regardless of the nature of the reinforcement, the overall behaviours of the masonry walls reinforced with the FRPs/TRC are governed by both the axial stiffness of the reinforcement and the compressive strength of the masonry substrate. [ABSTRACT FROM AUTHOR]

Textile-reinforced concrete (TRC) has many advantages, including corrosion resistance, but TRC is a novel composite material and there is limited experimental research on the flexural behavior of TRC members. This paper aims to experimentally evaluate the flexural behavior of TRC slabs reinforced with nine types of grid-type carbon fiber-reinforced plastic (CFRP) (hereafter referred to as carbon grid) with varying cross-sectional areas, spacings, tensile strengths, and elastic moduli of longitudinal strands. The experimental results show that the maximum load tends to be higher in specimens reinforced with carbon grids with small cross-sectional areas and spacings of strands but high tensile strength. Cross-sectional area and spacing were also revealed to influence the crack-formation stage behavior. On the other hand, stiffness decreased to approximately 8% or lower than the initial stiffness, with cracking in all carbon grid-reinforced specimens; post-peak behavior also exhibited dependency on tensile stress acting on the carbon grids under the maximum load, based on 80% of the tensile strength.

Textile-reinforced concrete is characterized by its high-performance load-bearing behavior. The basis of these properties is largely determined by the characteristics of the textile used. The textile in turn consists of fibers that are bonded together by means of a matrix (impregnation). Both the fiber material and the impregnation significantly influence the tensile and bonding properties of the textile. The performance of the impregnation depends largely on its stiffness. In this publication, the fiber strand stiffness is quantified by means of shore hardness measurements, and the influence of the fiber strand stiffness on the tensile and composite properties is presented. The Shore hardness is a kind of Young’s modulus. The tests can be performed on the end product (manufactured fiber strand) with little effort. The test setup was adapted to determine the Shore hardness on the fiber strand. A comparison between the hardness and tensile strength shows a direct correlation. A dependency can also be identified and described of the bond between the textile and the concrete and the hardness. The investigations shown make quantifying the fiber strand stiffness based on hardness appear reasonable.

Numerous concrete monuments built in the High Modern Era (turn of the 20th century until the 1970s) must now be repaired for preservation. Traditional concrete repair according to current guidelines involves considerable material removal, changing the appearance of the existing structure. With a combination of the material properties of high-/ultra-high-performance concrete (HPC/UHPC) with its dense microstructure and corrosion-free textile reinforcement (carbon and basalt), a high-performance mortar repair system can be developed. Such a system allows for concrete repairs with minimal material loss by using very thin layers that are durable and do not change the architectural character of the repaired monument. For the investigation of the load-bearing behaviour of a structural repair system using textile-reinforced, high-performance mortar, 20 mm thick slabs were produced and mechanically characterized. In the next step, the proposed repair system was applied to 70 mm thick old concrete slabs. The results show that a high surface tensile strength of 2.9 MPa was obtained. In a further step, the system will be applied to concrete pillars of transmission tower in Berus, adapted in terms of colour and structure and installed for long-term monitoring.

Textile-reinforced concrete (TRC) is a form of reinforced concrete, where conventional reinforcement is replaced with textiles or fibers. The high tenacity of the textile fibers results in flexible and durable concrete structures. The literature has been limited to TRC applications in retrofitting and nonstructural applications. Therefore, this article attempts to detangle the progressive research direction on the usage of TRC as a structural member. For this, (i) a bibliometric study using scientometrics analysis to visualize the keyword network, and (ii) qualitative discussions on identified research areas were performed. The literature was categorized into four main research areas, namely material properties of TRC, composite behavior of TRC, bond-slip relations, and TRC applications as structural elements. In addition, the advantages and disadvantages in the usage of TRC as a structural member are discussed in association with the identified research areas. Furthermore, the article proposes future directions to reinforce the research on the usage of TRC as a structural element.

This paper concerns a novel method of constructing shell structures from flat concrete plates by means of active bending. The method is described together with a series of experimental investigations. The theoretical background for this method is given in Berger et al., Actively bent concrete shells, Struct Concrete, 2020. The method makes use of the high capacity for rotation exhibited by thin concrete plates that are reinforced with highly elastic tensile reinforcement. When these plates are subjected to eccentrical forces introduced by external tendons they are raised and bent precisely into a desired curved shape. The method was investigated and refined along with a series of experiments which are the subject of this paper: uniaxial tensile tests on rovings to determine their elongation at fracture, bending tests on small concrete plates to determine possible radii of curvature, and large‐scale tests to demonstrate the erection process of actively bent shells. [ABSTRACT FROM AUTHOR]

Splitting forces due to bond action can lead to the premature failure of reinforced concrete structural components. In earlier research it was mentioned that it is mainly geometrical parameters that play a key role in the distribution and magnitude of the splitting forces in textile-reinforced concrete. However, so far no accurate geometrical characterisation of textile reinforcement has been performed which considers all the relevant properties of the material such as the regularly repeating variation in cross-sectional dimensions. In this paper, four geometrical parameters are introduced which permit a clear geometrical characterisation of fibre strands and allow for the comparison of different types of textile reinforcement. Furthermore, a broad parametric study was carried out for a pull-out test in which the parameters were varied, and the influence of these parameters on the splitting forces occurring in textile-reinforced concrete was visualised. Based on this parametric study, a mechanical model was established, which takes into account experimental data from previous research. This model allows for the calculation of the splitting forces occurring in textile-reinforced concrete when one short fibre strand is pulled out of the concrete. [ABSTRACT FROM AUTHOR]

In most countries, for the production and execution of concrete structures with textile reinforcement, building owners must have a general approval (e.g., "abZ" in Germany) or an individual license (e.g., "ZiE" in Germany). Therefore, it is quite common for building authorities to request experimental tests that evaluate the ultimate limit state (ULS) and the serviceability limit state (SLS). However, these experimental tests are detailed, time-consuming and expensive. A practical and simple design model would help to reduce the number of tests needed and would offer structural planners a useful tool. An important aspect is that such design model must fulfil a set of reliability requirements in order to guarantee an adequate safety standard. To this end, probabilistic calculations are required. For the setup of such model, different parameters must be considered, namely the effective depth d and the tensile failure stress of the textile ft for the concrete compressive strength fc. This article presents the probabilistic calculations needed to attain a general safety factor γT that satisfies all the safety requirements for the textile reinforcement of concrete structures with bending load. [ABSTRACT FROM AUTHOR]

Modelling of the anchorage behaviour of impregnated textile reinforcement The bond behaviour and the related anchorage behaviour of textile reinforcement cannot be deduced from the well‐established rules in RC‐building design, as textile reinforcement exhibits different geometric and mechanical properties. In cases where mechanical interlock is the decisive bond mechanism, a splitting failure was often observed in experimental testing. The assessment of component exposure to splitting failure has been conducted in the past mainly by experimental testing. In this paper a method is introduced on the contrary which allows for the calculation of the splitting failure mode for such a type of textile configuration. In the first step the bond relationship is extracted by means of experimental testing of specimens where a splitting failure can be ruled out. For this purpose a new test setup is introduced. Failure occurs by shearing off the ribs of the reinforcement (corresponds to the regularly repeating variation in cross‐sectional dimensions), which indicates high local stress concentrations in this area. On the basis of these findings a numerical model is established, where it is assumed that the bond transfer within a mesh width takes place in a discrete bond section (which represents the area with the high local stresses). This model allows for the prediction of the anchorage behaviour of textile‐reinforced concrete. Additionally the progress of the normal force in the fibre strand can be depicted. By comparing the normal forces per mesh width with a splitting resistance, an assessment can be given whether the component is exposed to splitting failure or not. [ABSTRACT FROM AUTHOR]

Two examples from practice for shear capacity of textile‐reinforced bridge decks Textile‐reinforced concrete (TRC) for new constructions combines high‐performance textiles with a new generation of high‐strength concretes. Due to the corrosion resistance of the non‐metallic reinforcement, the use of TRC for exterior applications is promising, especially with freeze‐thaw and de‐icing salt exposition. The concrete cover and dead loads can be reduced and the production of slender structural elements as well as thin slabs without additional waterproofing or protective decking becomes possible. During the design of several bridges in Remstal and in Ottenhöfen, theoretical models and experiences from previous research projects were used to apply TRC slabs without shear reinforcement. Accompanying the production and construction works, experimental investigations of shear capacity were carried out for quality control of the execution and for validation of assumptions. The present article shows the application potentials and challenges for the use of TRC in civil engineering structures. [ABSTRACT FROM AUTHOR]

With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases durability, and extends lifespan. For new components with such mixed reinforcement, applicable design concepts and engineering rules are necessary to accurately determine the structural and deformation behavior. To validate models and detailing rules previously developed, three large carbon reinforced concrete I-beams were designed and tested to failure with a realistic line load. CFRP bars served as principal bending reinforcement, whereas shear and flange reinforcement consisted of textile grids. Results showed that existing models for bending using variation of strain distribution as well as non-linear finite-element analysis predicted the flexural behavior of structural components with mixed reinforcement in ultimate limit state (ULS) appropriately. Yet, calculation of shear capacity requires further studies to determine textile reinforcement contribution and estimate reduction for concrete strength in reinforced compression struts. For serviceability limit state (SLS), three methods for determination of deflection delivered good results. In future, a rethinking is required with regard to the ductility and robustness of CFRP-reinforced concrete components. In this respect, pronounced cracking as well as the large ultimate strain and deflection compensate for the lacking yield capacity of the reinforcement. [ABSTRACT FROM AUTHOR]

In this study, the chloride ion diffusion and structural performance of beams reinforced with textile-reinforced concrete (TRC) were evaluated. The parameters investigated were chloride concentration, sustained load and number of textile layers. The results demonstrate that the content and diffusion coefficient of chloride increased with increasing chloride concentration. Higher chloride concentrations accelerated the crack propagation and deflection changes and caused the reduction of the load-carrying capacity of the beams. The sustained load promoted the chloride transport of the TRC, increasing the chloride ion content and diffusion coefficient and causing substantial damage to the microstructure of the TRC. In addition, the performance (such as cracking resistance, deflection and flexural capacity) of beams with a large sustained load ratio decreased to a less extent than did the performance of the unloaded beams. The content and diffusion coefficient of chloride in the unstrengthened beams were obviously larger than those in the strengthened beams, but increasing the textile layers number had little influence on these factors. In addition, for the unstrengthened beams, the cracks and deflections developed rapidly, and the load decreased greatly, especially the cracking load. Finally, in accordance with Fick's second law of diffusion, a chloride diffusion equation in TRC layers under new boundary conditions was proposed. [ABSTRACT FROM AUTHOR]

The service life of bridges is often threatened by an insufficient shear force capacity in the transverse direction as well as by leakages in the sealing layer, which leads to chloride ingress and therefore corrosion damages. To prevent expensive repair work and traffic obstructions, a thin, multifunctional interlayer of textile‐reinforced concrete called SMART‐DECK was developed. This interlayer provides three functions: A full‐surface moisture monitoring in real‐time, a preventive cathodic corrosion protection, and an increase of the shear force capacity. The operator of the bridge is able to monitor the condition of the sealer in real‐time. The relevant data are transmitted via the internet and show the condition of the sealer in a simple color scheme. If leakage occurs, the cathodic corrosion protection can be switched on to protect the reinforcement from corrosion damages. The renewing of the damaged bridge deck sealing has not to be carried out immediately but can be postponed over years, for example, to periods with little traffic. In this paper, the scientific approach for the realization of the system is presented, beginning with laboratory pretests on the materials and numerical simulations. The results are used to test the functions of the system in the laboratory and later on two demonstrators. An outlook will present the next research questions. [ABSTRACT FROM AUTHOR]

Design model with an iterative and closed approach for textile reinforced concrete structures with bending load – clear bending load and a combination with normal force For the realization of the known concrete structures with textile reinforcement the builder‐owner needed either a general approval (abZ) or an individual license (ZiE). Therefore the building authority requested detailed, time‐consuming as well as expansive experimental test for the ultimate limit (ULS) and serviceability limit state (SLS). Especially the research on bending behavior was necessary. A practical and simple design model could help to reduce the number of tests and offer the tool to the structural planer for the design. This article presents a general engineering model for a clear bending load and a combination with normal force. For this purpose the known material laws for the concrete from the code will be used. The suggestion for the stress‐stain‐curve for the textile reinforcement will be deviated from the published research work. The model will be verified by extensive experimental tests, where the necessary parameters are respected. Finally a design model will be suggested, which is based on the engineering model. The differences are the additional safety factors, which are required for the design. [ABSTRACT FROM AUTHOR]

The improved effect of the bonding behavior of concrete and reinforcement is a critical indicator for estimating the validity of strengthening measures. The bonding behavior of unconfined or textile reinforced concrete (TRC)-confined concrete and a plain or deformed reinforcement was comparatively analyzed via the pull-out tests, and the influence of chloride wet-dry cycles also was considered on the bonding behavior. Moreover, the bonding behavior was further revealed from the view of energy. The study results indicated that the bonding failure of specimens with a deformed reinforcement was changed after TRC confinement, showing a certain ductile failure characteristic, and the integrity of the confined specimens was ensured at failure. The impact of chloride attack on the bonding behavior of concrete and a plain or deformed reinforcement was different under the unconfined or TRC-confined condition. The deterioration mechanism of the bonding behavior needs to be further investigated when the reinforcement is corroded seriously. The results from the energy analysis are consistent with the pull-out test results. [ABSTRACT FROM AUTHOR]

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This special issue presents the latest advances in the field of Textile-Reinforced Cement Composites, including Textile-Reinforced Concrete (TRC), Textile-Reinforced Mortar (TRM), Fabric-Reinforced Cementitious Matrix (FRCM), etc. These composite materials distinguish themselves from other fibre reinforced concrete materials by their strain-hardening behaviour under tensile loading. This Special Issue is composed of 14 papers covering new insights in structural and material engineering. The papers include investigations on the level of the fibre reinforcement system as well as on the level of the composites, investigating their impact and fatigue behaviour, durability and fire behaviour. Both strengthening of existing structures and development of new structural systems such as lightweight sandwich systems are presented, and analysis and design methods are discussed. This Special Issue demonstrates the broadness and intensity of the ongoing advancements in the field of Textile-Reinforced Cement composites and the importance of several future research directions. [ABSTRACT FROM AUTHOR]

• Modularity to facilitate the current construction of slender concrete shells. • Limited set of formworks whilst achieving a large variety of shell configurations. • Form finding and finite element simulations create and verify the obtained results. • Scaled-down prototype of one shell confirms the feasibility of the design method. • Design method strives towards making resource-effective innovative shell structures. Thin concrete shells can span large distances thanks to their structural efficiency, following the optimum force flow. Despite the efficient use of material of well-designed shells, their construction suffers from labor-intensive and time-consuming fabrication techniques. This research therefore proposes a design method for the facilitated manufacturing of freeform shell structures. The manufacturing process has been considered from the design phase on, by generating an extensive range of different shell configurations based on a limited set of form-found modules and thus formworks. The challenge was to define which curved module geometries, after assembly, lead to the largest variety of freeform surfaces. More than sixty configurations resulted from a set of four modules only. This paper will discuss the form-finding process as well as the geometrical arrangement using tessellation patterns for the achievement of those modular configurations, going from domed to undulating shell shapes. In order to evaluate the structural efficiency of the shapes, twenty modular configurations were selected and analyzed under self-weight, using finite element simulations. To conclude, a prototype of one modular base element has been built, using a reusable casting wax in combination with a grid shell box, as the main parts of the formwork. The results demonstrate the structural feasibility and limitations of the modular shell design strategy. The modular approach contributes to circularity by encouraging reuse and allowing various combinations with a repeating set of modules, striving as such towards resource-effective innovative shell structures. [ABSTRACT FROM AUTHOR]

The effectiveness of textile-reinforced concrete (TRC) and steel-reinforced concrete (SRC) in the flexural performance of rectangular concrete beams was investigated in this study. To better understand TRC behaviour, large-scale concrete beams of 120 × 200 × 2600 mm were tested and analysed in this work. Cover thickness, anchoring, and various layouts were all taken into consideration to assess the performance of beams. In addition, bi-axial and uni-axial TRC beams and SRC beams were classified according to the sort and arrangement of reinforcements. The findings showed that anchoring the textiles at both ends enhanced load resistance and prevented sliding. The ultimate load of the tow type of textile reinforcement was higher, attributed to the increased bond. Variations in cover thickness also change the ultimate load and deflection, according to the findings. Consequently, in this investigation, the ideal cover thickness was determined to be 30 mm. Furthermore, for the similar area of reinforcements, the ultimate load of TRC beams was noted up to 56% higher than that of the SRC control beam, while the deflection was roughly 37% lower.

Textile-reinforced concrete (TRC) as a novel high-performance composite material can be used as a strengthening material and component bearing load alone. The flexural performance of TRC beams strengthened with textile reinforcement such as carbon tows was experimentally examined and associated with those of steel-reinforced concrete (SRC) beams. Through four-point bending tests, this research explores the effects of textile layers and dosages of short textile fibre on the flexural strength of concrete beams. A total of 64 prism samples of size 100 mm × 100 mm × 500 mm were made, flexure-strengthened, and tested to evaluate various characteristics and the efficiency of TRC versus SRC beams. TRC beams performed exceptionally well as supporting material in enhancing concrete’s flexural capacity; in addition, TRC’s average ultimate load effectiveness was up to 56% than that of SRC specimens. Furthermore, the maximum deflection was about 37% lesser than SRC beams. The results showed that by increasing the number of layers, the TRC’s effectiveness was significantly increased, and the failure mode became more ductile.

Shear strength of carbon‐reinforced concrete members without shear reinforcement – Experimental investigations of the influence of the reinforcement ratio on load‐bearing behaviour Fibre‐reinforced polymers (FRP) as reinforcement for concrete members in structural engineering are becoming increasingly important. Compared to conventional steel reinforcement, FRP reinforcement is different in terms of modulus of elasticity, tensile strength and bond behaviour. If concrete compression failure can be excluded, members with the same mechanical ratio of longitudinal reinforcement have the same bending load bearing capacity. The high tensile strengths of FRP reinforcement can lead to a reduced required reinforcement area and thus geometric ratio of longitudinal reinforcement. This effect leads to a reduced shear strength and increased crack widths and spacings. This article presents and evaluates experimental investigations on the shear strength of concrete members without shear reinforcement. Two different member types were analysed: slabs with textile carbon reinforcement and beams with carbon bars. For a direct comparison with conventionally reinforced members, reference tests with steel reinforcement and comparable mechanical reinforcement ratio were carried out. In addition to a detailed description of the specific properties of the used materials and a comparison of the load‐bearing and deformation behaviour of the members, a precise evaluation of the cracking behaviour is shown. Finally, the influence of the reinforcement ratio on the shear strength is presented and the resulting conclusions are summarised. [ABSTRACT FROM AUTHOR]

The study examines the use of hybrid carbon-based textile-reinforced concrete elements with self-sensing capabilities to quantitatively detect wetting events within cracked zones. The self-sensory structural element combines the advantages of AR-glass and carbon-based textile-reinforced concrete for thin-walled structural elements with those stemming from the electrical properties of reinforced carbon rovings. The article investigates the sensitivity of sensory carbon rovings to distinguish between the magnitudes of various wetting events, which is associated with the severity of the cracking, according to two electrical setups (DC and AC circuits). The sensing concept takes advantage of the continuous configuration of the carbon rovings, which enables direct connection of the roving ends to the data acquisition system, and of the manufacturing process that two carbon rovings are placed adjacent to one another. Therefore, it is assumed that wetting events electrically short-circuit the two adjacent rovings. The sensitivity of the two electrical setups is experimentally investigated and performed on a couple of bared carbon rovings and on a cracked textile-reinforced concrete beam. Test results demonstrate the sensitivity of the sensing capabilities of the carbon rovings to detect and distinguish between the magnitudes of the wetting events and consequently the severity of the cracking. [ABSTRACT FROM AUTHOR]

Featured Application: The present paper contributes to the discussion on modeling methods appropriate for the structural analysis of thin-walled concrete shells, a rapidly developing field of material and structural design utilizing the high-performance cementitious composites reinforced with non-metallic reinforcement. An effective modeling support is paramount for the derivation of reliable and economic design and assessment principles in a wide range of applications. The paper focuses on the specifics of macro-scale modeling of thin-walled textile-reinforced concrete shells. Application of layered shell finite elements requires systematic procedures for identification of material characteristics associated with the individual layers within the cross section. The identification of the material parameters describing the tensile behavior of a composite cross section is done using data obtained from the tensile test. Such test is usually performed only for a reference configurations with a simple layup of fabrics and a chosen thickness. The question is how to derive the strain-hardening response from the tensile test that is relevant for a changed cross-sectional configuration. We describe and discuss scaling and mixture rules that can be used to modify the material parameters for modified cross-sectional layups. The rules are examined in the context of the test results obtained on a shell that was reinforced non-uniformly, with varying types of textile fabrics and varying thickness within the shell surface. [ABSTRACT FROM AUTHOR]

A reliable and economic utilization of textile-reinforced concrete in construction requires appropriate design concepts. Unlike designs for bending, the development of models for shear is still the subject of current research. Especially for thin slabs, systematic experimental investigations are lacking. In this paper, the results of an experimental campaign on 27 carbon-textile reinforced slab segments tested in three-point bending are presented. The shear-span to depth ratio and member size were key variation parameters in this study. Increasing the structural depth of members led to a reduction in relative shear strength, while variation of shear slenderness controlled the efficiency of direct stress fields between load introduction and support. Interestingly, direct load transfer was activated up to a shear slenderness ratio of 4, which is significantly higher than in reinforced concrete (a/d < 2.5–3) and may result from the bond characteristics of the textile reinforcement. The experimental shear strengths were compared to predictions from existing models for shear of fiber-reinforced polymer (FRP)-reinforced concrete. The study shows that these FRP calculation models also predict the ultimate shear force for textile-reinforced concrete (TRC) tests presented in this paper with sufficient accuracy. Existing approaches for the size effect seem transferable as well. In order to validate the models for general use in TRC shear design, a compilation and comparison with larger experimental databases is required in future works. [ABSTRACT FROM AUTHOR]

• An experimental and analytical study on the flexural creep of concrete reinforced with resin-impregnated woven fabrics is performed. • An analytical viscoelastic model is developed based on multi-scale micromechanics, classical lamination theory, and Alfrey's correspondence principle to predict the upper and lower limits of creep deformation of TRC. • Short-term and long-term creep tests are conducted to evaluate the proposed model. • The results showed that a probabilistic model is more appropriate to predict the creep behavior of TRC rather than a deterministic model. Textile-reinforced concrete (TRC) is a promising composite material that has growing demands in the construction industry. The time-dependent behavior of TRC is a less-studied characteristic of these materials. Since the wide use of TRC in constructing thin-walled concrete structures, the present study performed an experimental and analytical study on the flexural creep of concrete reinforced with resin-impregnated woven fabrics. An analytical viscoelastic model is developed based on multi-scale micromechanics, classical lamination theory, and Alfrey's correspondence principle to predict the upper and lower limits of creep deformation of TRC. Due to uncertainty observed in the cracking force of TRC, this parameter is considered a random variable with normal distribution. Probabilistic intervals are calculated for TRC midspan creep deflections. Short-term and long-term creep tests are conducted to evaluate the proposed model. The results showed that a probabilistic model is more appropriate to predict the creep behavior of TRC rather than a deterministic model. [ABSTRACT FROM AUTHOR]

In most countries, for the production and execution of concrete structures with textile reinforcement, building owners must have a general approval (e.g., “abZ” in Germany) or an individual license (e.g., “ZiE” in Germany). Therefore, it is quite common for building authorities to request experimental tests that evaluate the ultimate limit state (ULS) and the serviceability limit state (SLS). However, these experimental tests are detailed, time-consuming and expensive. A practical and simple design model would help to reduce the number of tests needed and would offer structural planners a useful tool. An important aspect is that such design model must fulfil a set of reliability requirements in order to guarantee an adequate safety standard. To this end, probabilistic calculations are required. For the setup of such model, different parameters must be considered, namely the effective depth d and the tensile failure stress of the textile ft for the concrete compressive strength fc. This article presents the probabilistic calculations needed to attain a general safety factor γT that satisfies all the safety requirements for the textile reinforcement of concrete structures with bending load.

With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases durability, and extends lifespan. For new components with such mixed reinforcement, applicable design concepts and engineering rules are necessary to accurately determine the structural and deformation behavior. To validate models and detailing rules previously developed, three large carbon reinforced concrete I-beams were designed and tested to failure with a realistic line load. CFRP bars served as principal bending reinforcement, whereas shear and flange reinforcement consisted of textile grids. Results showed that existing models for bending using variation of strain distribution as well as non-linear finite-element analysis predicted the flexural behavior of structural components with mixed reinforcement in ultimate limit state (ULS) appropriately. Yet, calculation of shear capacity requires further studies to determine textile reinforcement contribution and estimate reduction for concrete strength in reinforced compression struts. For serviceability limit state (SLS), three methods for determination of deflection delivered good results. In future, a rethinking is required with regard to the ductility and robustness of CFRP-reinforced concrete components. In this respect, pronounced cracking as well as the large ultimate strain and deflection compensate for the lacking yield capacity of the reinforcement.

This special issue presents the latest advances in the field of Textile-Reinforced Cement Composites, including Textile-Reinforced Concrete (TRC), Textile-Reinforced Mortar (TRM), Fabric-Reinforced Cementitious Matrix (FRCM), etc. These composite materials distinguish themselves from other fibre reinforced concrete materials by their strain-hardening behaviour under tensile loading. This Special Issue is composed of 14 papers covering new insights in structural and material engineering. The papers include investigations on the level of the fibre reinforcement system as well as on the level of the composites, investigating their impact and fatigue behaviour, durability and fire behaviour. Both strengthening of existing structures and development of new structural systems such as lightweight sandwich systems are presented, and analysis and design methods are discussed. This Special Issue demonstrates the broadness and intensity of the ongoing advancements in the field of Textile-Reinforced Cement composites and the importance of several future research directions.