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The paper explores the sensing capabilities of a carbon based textile reinforced concrete (TRC) composite element to monitor its structural mechanisms. The concept is based on continuous carbon rovings knitted into glass textile mesh that simultaneously serve as the structural reinforcement and as the sensory system. The loading procedures which starts from a healthy state, to micro and macro cracked state, and ends with a completely pull-out of the tensioned rovings is strongly affected by the micro-structural mechanism of the carbon rovings within the concrete matrix. It is found that the measured electrical resistance is characterized by this mechanism and can reflect the structural condition. Therefore, it can serve as a structural health monitoring system. The paper demonstrates these sensing capabilities along the entire range of the loading procedure, even up to progressive failure mechanism, where traditional sensing devices usually failed to produce meaningful information.

This paper presents the results of an experimental investigation into the durability behaviour of textile-reinforced concrete (TRC) subjected to both tensile and bending loads to compare its macroscale characterization. Composites are produced as a laminate material using 2 and 6 layers of glass fibre mat as reinforcements. The instantaneous and long-term (durability) properties of composite TRC are identified by tensile and flexural testing with specimens made from the same fresh mortar. The long-term tests are conducted in two ageing environments: natural ageing, which was conducted under the laboratory atmosphere (20 °C and 50% RH), and accelerated ageing, which consisted of immersion of the specimens in hot water at 50 °C. The durability performance of TRC is evaluated by the reduced macroscale performance and damage mechanisms. The effects of the reinforcement ratio, testing conditions, and thermal conditions on the long-term response of TRC are investigated, and the microstructure of both matrix and fibre is observed and discussed after the tests with observations via scanning electron microscopy (SEM). The addition of layers of glass fibre (reinforcement ratio) increased the strength capacity and the first macro-crack strength of TRC in both tensile and bending tests. The ultimate strength value of the TRC composites obtained from the tensile test is lower than that from the bending test over the same tested days as a result of the different redistribution mechanisms; however, the difference between tensile and flexural stress remains approximately equal with similar deviations. An increase in the tensile and flexural strength capacity over the ageing time is observed before 90 days of ageing. However, after 90 days, the test results showed a loss of ductility of the accelerated aged specimens.

A novel sandwich element design consisting of two facings made of carbon reinforced Textile Reinforced Concrete (TRC), a low density foamed concrete (FC) core and glass fibre reinforced polymer (GFRP) connecting devices was experimentally investigated according to quasi-static and cyclic quasi-static four-point bending. Optical measurements based on Digital Image Correlation (DIC) were taken during testing to enable a detailed analysis of the bending behaviour and level of composite action. A model, verified by the experiments, was developed based on non-linear finite element analysis (NLFEA) to gain further insight on the failure mechanisms. Under both loading conditions, the bending behaviour of the TRC-FC composite elements was characterized by favourable load bearing capacity, partial composite action, superior ductility and multiple fine cracking. The connecting devices were found to be the critical elements causing the initial failure mechanism in the form of localized pull-out within an element.

Textile-reinforced concrete (TRC) as a novel composite material offers a wide range of capabilities and flexibility in the manufacturing of thin-walled, lightweight structures. The application of textile reinforcement in fine aggregate high-performance concrete has enabled the dimensioning of structural concrete in very small thicknesses. This possibility allows for the fabrication of thin-walled TRC shell structures with complex geometries. On the other hand, structural planning and construction require new modeling approaches to comprehend the structural behavior of such forms. In this paper, we present the fabrication procedure of a large-scale TRC vault shell, together with the performed experimental study. The shell structure was tested under a two-step loading scenario to study the load-bearing behavior. The particular focus of the paper is on the analysis of the structural behavior by means of an anisotropic strain-hardening material model specifically developed for the simulation of TRC shells. The prediction obtained using the nonlinear finite element simulation has been compared with the test results to validate the modeling approach. The performed studies are used to evaluate and discuss the structural redundancy included in the applied linear ultimate limit state assessment procedure.

Reinforcement and repair of reinforced concrete structures is often more economical and sustainable (less cement consumption, less CO 2 production) than reconstruction. Currently, the solution of reinforcement/repair by carbon-epoxy materials applied to outer surfaces of the structures is routinely used. However, these composites have limitations in terms of cost, fire resistance and sustainable development criteria. The textile reinforced concrete (TRC) mineral-based composite is envisaged as an alternative solution that can solve, at least partially, the above drawbacks. This work aims to experimentally assess contributions of the strengthening/repair of slender reinforced concrete beams subjected to bending by applying the TRC composite. In the first approach, the use of TRC composites in the case of the repair/strengthening of tank shells will be evaluated on the basis of slender beams. Twelve reinforced concrete “beams” are tested for quasi-static monotonic loading by bending tests over four points among 10 beams that have been reinforced/repaired by composite materials . Several parameters including two different modes of curing conditions (28 days immersion in water at 20 °C; 28 days left in air at 20 °C, 50 RH), and two different types of configurations of the beams (with and without pre-cracking) have been considered. This study highlights the mechanical performance of TRC in strengthening/repair of the reinforced concrete beams by analysing the changes in global behaviour (e.g., load/deflection, failure mode, flexural rigidity) and local behaviour (e.g., deformation of steel, pattern cracking, the crack opening). Further evaluation of the local behaviour of TRC should be conducted to address the damage mechanism by multi-cracking of the material and changing the opening of the crack located on the face of the composite.

The objective of this study is to provide, by describing the experimental approach, a detailed description of the behaviour of multilayer Textile-Reinforced Concrete (TRC) composites under axial (tensile) olygocyclic fatigue. Different multilayer TRC composite configurations are proposed based on the carbon grid and glass grid associated with the carbon and/or glass fibre rods. A parametric study is conducted to validate the performance of these composite configurations with fatigue loads of 60% and 80% of the rupture load over 100 cycles. The experimental results show an increase in the rigidity and the dissipative capacity of the composite under fatigue loading with an invariance of the degradation mechanisms. An improvement in composite performance is observed with the addition of carbon and/or glass rods. Damage to composite during experiments is characterized by cracks orthogonal to the effort; their density is proportional to the applied fatigue load. The monotonous tensile tests (Post Fatigue) show that global and macroscopic performances have not declined after 100 cycles. The latex resin integration allows an improvement in residual capacities of composites that are subjected to cyclic tensile loading of up to 1000 cycles. The TRC composite performance increases with the rate of loading in the case of reinforcement with large size mesh.

In the present work, the flexural behavior of carbon textile reinforced concrete (TRC) I-beams is investigated. Four-point bending tests were performed in I-beams, considering SBR-laminated textile and the following conditions: (a) plain cementitious matrix; (b) plain matrix and sand-coated textile; and (c) strain hardening cement-based composite (SHCC) matrix. The main goal of the research was to correlate the improvements on interface and matrix properties with the crack pattern, failure mode and ductility. For a comprehensive discussion, full mechanical characterization was performed and a design model is proposed for a better evaluation of the experimental results. Cracking behavior was greatly improved for conditions (b) and (c) with respect to (a), due to enhanced bonding between reinforcement and matrix in the former and due to fiber bridging mechanism in the latter. Beams with plain matrix exhibited brittle failure, whereas the beam having SHCC matrix showed premature local failure near load application point, resulting in an apparent ductility due to concrete softening mechanism. The reduced cracking load and the premature flange detachment along web-flange junction for condition (a) are also discussed. The proposed model is also validated through comparison with experimental results available in the literature.

Thin-walled shell structures made of textile-reinforced concrete (TRC) exhibit a high load-bearing capacity and considerable ductility. However, the material behavior exhibits several interacting mechanisms of material disintegration that result in a complex, highly nonlinear structural response. In this paper, an anisotropic material model for TRC will be discussed that is able to capture those effects. The calibration of the material model is performed based on an inverse analysis using the strain-hardening response measured in a uniaxial tensile test. Finally, we validate the material model through a finite-element simulation of three-point bending tests as well as the complex biaxial load-bearing behavior as observed in slab tests with central loading. In this context, further issues such as the influence of large deflections and geometrical nonlinearity will be investigated. The calibrated model provides a valuable tool for an in-depth analysis of the structural behavior of thin-walled TRC shell structures. This is especially important for a realistic prediction of the deflections in the cracked state as well as load-bearing reserves resulting from stress redistributions.

Textile reinforced concrete (TRC) has been increasingly used in strengthening existing structures and building new lightweight structures, and the interfacial bond plays a fundamental role in optimising the structural performance and design. This paper, for the first time, presents an analytical solution to predict the interfacial response of a textile reinforced concrete composite between two cracks. The closed form expressions not only apply to predict pull-out force vs. displacement relation, but also simulate interfacial response between two locations. The interfacial behaviour, including the interfacial relative slip, the shear stress distribution, and the axial stresses of the reinforcement and the matrix, could be obtained. While the numerical parametric studies are based on carbon fibre textile reinforced concrete, the theoretical solutions are applicable to other embedded type reinforced composites. The accuracy of the derived theoretical model has been validated using previously published researches of similar problems and the FEM simulation. The numerical parametric studies concluded that increasing the load difference at the two ends of the reinforcement (increasing β value) may shift the critical failure mode from interfacial debonding to material yielding. Furthermore, using micro/short fibres in the concrete matrix (triggering a negative η value) will significantly improve the interfacial performance. It is also found that for a concrete composite with a high reinforcement ratio, it is necessary to use either ultra-high strength concrete or fibre reinforced concrete matrix to fully use the high tensile strength capacity of carbon fibres.

This paper presents the design and experimental validation of a durable textile reinforced concrete (TRC) panel that can be used to furnish a stay-in-place (SIP) formwork and a protective layer over the outer surface of the reinforced concrete (RC) elements, which require high durability and long service life. The objectives of this study are to increase the flexural capacity and to improve the durability of the RC elements by employing an SIP TRC formwork panel. A durable binder system was designed to offer excellent durability performance in a chloride-rich environment. Six full-scale RC slab-type specimens were casted on the SIP TRC formwork. The load-deflection behaviour of the full-scale slab specimens was compared with the analytical solutions. The results of a full-scale flexural failure test indicated that the ultimate flexural capacity of the slab specimens with the TRC formwork was at least 141% greater than that of the RC slab without the TRC formwork.

Textile-reinforced concrete is ideally suited to complement ordinary steel-reinforced concrete, as the use of textile reinforcement with its outstanding mechanical properties and durability allows the construction of slender, lightweight structural elements. Despite the increased interest in this innovative composite material making it a subject of various research projects carried out during the past two decades, questions regarding its specific properties remain. An economically driven trend towards using rovings with a high yarn count and coated with a stiff impregnation material has surfaced in recent years, which has led to an increased occurrence of splitting failures in textile-reinforced concrete elements. This paper describes investigations aimed at clarifying the theoretical background of this failure mode. Preliminary experimental studies were carried out to identify and quantify the impact of several influencing parameters thought to be responsible for inducing longitudinal cracking in textile-reinforced concrete. In subsequent numerical computations with a particular focus on bond behaviour, the stress distribution in the concrete during fibre strand pull-out was visualised. The analysis of the different investigations carried out by the authors showed that the geometric characteristics of the fibre strands have a significant influence on bond behaviour and particularly on splitting failure in textile-reinforced concrete.

The paper presents a non-linear structural model for evaluating the macro-structural response as well as the distribution of the internal stress resultants of textile reinforced concrete composites under uniaxial static loading. The equilibrium equations and the appropriate boundary conditions are derived on the basis of the variational principle of the minimum potential energy approach. Various aspects related to the unique micro-structural behavior associated to the bonding mechanism of the yarns and the concrete matrix, as well as the nonlinearity of both materials, are taken into consideration and implemented in the variational principle. The obtained set of nonlinear equilibrium equations is formulated according to the mixed formulation which yields a set of first order nonlinear ordinary differential equations. The solution procedure is conducted by the mixed-half-station interlacing-grid finite-difference scheme and by Newton–Raphson method. Results provided by the proposed model are compared to experimental tests from the literature and demonstrate its generality, accuracy, simplicity, and its easy implementation in various experimental setups. It is further demonstrated that the presented structural model can successfully capture the macro-structural response and gives an insight into the micro-structural mechanism involved in the load carrying capacity of the TRC composite element.

Retrofitting of damaged and/or ancient masonry structures is of significant importance to increase their structural safety. In this study, a retrofitting technique of basalt-textile-reinforced concrete (BTRC) was used to repair partially damaged rectangle masonry columns, and the repairing efficiency was assessed by different parameters. Compression tests with different eccentricities were conducted to explore the mechanical behaviors of initial and BTRC retrofitted masonry columns. The data in terms of crack patterns, load-displacement curves, peak load, ductility and longitudinal strains were analyzed and discussed in depth. Results show that BTRC retrofits can substantially improve the load carrying capacity and ductility of the partially damaged masonry columns under different eccentric loads that display different damage characteristics. The uniaxial constitutive (NTR-PP, NTR-PB and Sargin) models of masonry predict a relatively safe bearing capacity of BTRC-confined columns under eccentric loadings. This BTRC retrofitting technique with the features of cheap, easy-to-construct, long durability and environmental friendliness shows promising potentials in engineering applications. The findings of this study provide an effective way for repairing ancient and/or damaged masonry structures with BTRC.

Textile-Reinforced Concrete (TRC) is a new construction material that offers several advantages over steel reinforced concrete. These advantages are particularly relevant for applications requiring thin-walled, structural elements with a high load-carrying capacity. For example, sandwich panels, made of two thin TRC facings and a core of polymeric rigid foam present an attractive choice for modern building envelopes. These combine low weight with a high structural capacity, while simultaneously fulfilling structural and physical demands. The development of sandwich panels made of TRC has been the subject of several research projects at the Institute for Structural Concrete of RWTH Aachen University in Germany. The present paper outlines the testing procedure of sandwich sections made of TRC and their load-carrying behaviour subjected to tension, shear forces, and bending moments.

This experimental and numerical study is related to the repair and strengthening of reinforced concrete beams with TRC (textile-reinforced concrete) and hybrid (TRC + carbon and glass rods) solutions that are positioned relative to the more traditional ones such as the CFRP (carbon fibre-reinforced polymer) solutions. Beyond the good performances highlighted experimentally, especially in terms of bearing capacity and different failure modes (e.g., possibility to avoid peeling off), it is clear from this work that the TRC, despite its nonlinear behaviour (multi-cracking), does not allow a significant gain in ductility. From a numerical perspective using numerical modelling (smeared crack approach), the overall behaviour of beams reinforced with TRC (or the hybrid solutions) based only on the textile “efficiency factor” (or the average contribution of the filaments) as a calibration coefficient was found to be significantly satisfactory. Numerical modelling performed on all the beams also highlighted the fact that the axial stiffness of reinforcements (even in the case of a cracking material) governing the overall behaviour of beams could, at least in part, explain the observed failure modes.

Composite tubes comprised of a plastic core and a textile reinforced concrete coating offer many advantages compared to conventional tube materials. The inner plastic tube, highly resistant against incrustation and aggressive substances provides a sealing function and transports the medium; the outer coating of the concrete tube resists both inner and outer pressure. The positive properties of the comprising materials are ideally combined and compensate for their disadvantages. The reinforcing textiles are bi-axial multi-plies manufactured on Malimo stitch-bonding machines. They have been machine coated to ensure maximum fibre strength and good processing properties. The addition of short fibres to the concrete further improves the excellent load bearing capacity of the composite tubes.