Carbon Textile Reinforced Concrete Research Articles

Electrical Heating of Carbon Textile Reinforced Concrete—Possible Effects on Tensile Load-Bearing Behavior

Carbon-textile-reinforced concrete (CTRC) is currently used as a high-performance composite material in the construction industry, comprising concrete and a non-metallic reinforcement. In addition to remarkable material properties such as tensile-load-bearing behavior, durability and density, this innovative material features high electrical conductivity, offering the potential for electrical heat generation within building components. This paper contributes to the field by exploring the unique combination of properties exhibited by carbon-textile reinforcements (CTR) electrically heated up to 80 °C. The impact of the electrical heating of CTR was evaluated by conducting stationary tests on load-bearing behavior. The tests were conducted on two different CTRs: one impregnated with polystyrene, and the other with epoxy resin additionally surface-modified with quartz sand. In order to quantify the influence of individual material parameters, tensile tests were conducted on the components comprising CTR and mortar, as well as the composite CTRC. The analysis focused on electrically heated carbon-textile reinforcements, comparing them through experiments conducted at varying ambient temperatures. This study presents pioneering findings on heated CTRC, determining that electrical heating decreases tensile strength with increasing temperature for the investigated reinforcement materials. The softening of the impregnation materials proved to be a decisive factor. This interdisciplinary approach bridges materials science with thermal management in construction, offering insights into the practical applications of CTR in innovative building designs.

Material‐minimised construction with extruded textile reinforced concrete

AbstractThe use of textile reinforced concrete (TRC) is particularly suitable for producing sustainable, material‐minimised components, as it allows for a significant reduction in the amount of concrete cover required compared to steel reinforced concrete (SRC). Instead of steel, fibres made of glass, aramid or carbon are used as reinforcement, which are processed from rovings into textiles with a polymer or mineral impregnation. Among these, carbon reinforcements have the highest tensile strength and alkali resistance, making them the most durable in concrete and requiring less maintenance over time. An innovative approach is the production of TRC structures by means of extrusion, in which the stiff, fresh concrete is continuously pressed through a shaping mouthpiece, giving the product its final shape. Within the scope of the CRC/Transregio 280, a new mouthpiece was developed that enables the horizontal introduction of stiff, impregnated textiles. The carbon TRC produced in this process showed a textile stress of up to 4,000 MPa. Additionally, solutions are presented that allow the characterization of stiff, fresh concrete and technical limits for shaping fresh, extruded TRC elements. The potential of this new production method is illustrated through the example of a compound component made of extruded TRC elements.

Fabrication of lightweight, carbon textile reinforced concrete components with internally nested lattice structure using 2-layer extrusion by LabMorTex

This paper describes the concept, form finding, fabrication and experimental testing of prototype innovative concrete components made of extruded and transformed carbon textile reinforced concrete (TRC). The components consist of two thin-walled concrete facings that are connected by an internally nested lattice structure made of carbon TRC. Through an innovative process, thin carbon TRC stripes with a width of 10 mm were extruded with 2 textile grids and then shaped into a counter arched structure following a sinusoidal wave. The components with internally nested lattice structure represent a lightweight structural system with a drastic saving of dead load compared to conventional steel reinforced concrete (SRC) components. The design process as well as the manufacturing process, concrete mixing, material and experimental testing are presented. The results indicate that sandwich wall components with up to 76 % less use of materials in comparison to steel reinforced constructions can be realized. In addition, an outlook for the production of further components from extruded TRC components is given, which are suitable for use as ribbed ceilings and which show up to 30 % less emissions in Global Warming Potential (kg CO2e/(service life)) than a comparable component with steel reinforcement based on the Life Cycle Assessment (3cradle-to-gate) with up to 77 % concrete saving.

Study on the Axial Load Response of RC Columns Confined by CTRC Subjected to Dry-Wet Cycles

To investigate the axial load response of reinforced concrete (RC) columns confined by carbon textile-reinforced concrete (CTRC) under chloride attack, 24 CTRC-confined square columns and 12 unconfined columns were tested under axial load, while considering the influences of dry-wet cycles, textile ratios, stirrup ratios, and section sizes. The experimental results indicate that the corrosion resistance and compression performance of RC columns under chloride ion erosion were significantly improved by CTRC. The corrosion of the RC column with CTRC confinement was remarkably reduced with a maximum of 63.9% in the chloride salt environment. The maximum increments of bearing capacity and ductility of CTRC-confined columns were 30.9% and 87.7%, respectively, compared with unconfined columns. In addition, bearing capacity, ductility, and deformation energy were also affected by stirrup ratios and section sizes. Finally, the semi-empirical and semi-theoretical analytical models of the stress-strain relationship and axial-bearing capacity were proposed based on the experimental data and theoretical analysis. The compound confinement effects of CTRC and corroded stirrups on core concrete was considered in the proposed models. The models correlated well with the experimental data.

Investigation of the Failure Modes of Textile-Reinforced Concrete and Fiber/Textile-Reinforced Concrete under Uniaxial Tensile Tests

Recently, innovations in textile-reinforced concrete (TRC), such as the use of basalt textile fabrics, the use of high-performance concrete (HPC) matrices, and the admixture of short fibers in a cementitious matrix, have led to a new material called fiber/textile-reinforced concrete (F/TRC), which represents a promising solution for TRC. Although these materials are used in retrofit applications, experimental investigations about the performance of basalt and carbon TRC and F/TRC with HPC matrices number, to the best of the authors' knowledge, only a few. Therefore, an experimental investigation was conducted on 24 specimens tested under the uniaxial tensile, in which the main variables studied were the use of HPC matrices, different materials of textile fabric (basalt and carbon), the presence or absence of short steel fibers, and the overlap length of the textile fabric. From the test results, it can be seen that the mode of failure of the specimens is mainly governed by the type of textile fabric. Carbon-retrofitted specimens showed higher post-elastic displacement compared with those retrofitted with basalt textile fabrics. Short steel fibers mainly affected the load level of first cracking and ultimate tensile strength.

Influence of mechanical characterization technique on Carbon-TRC constitutive relations

The behavior of textile reinforced concrete (TRC) structures depends on the properties of the matrix and fiber used, as well as on the interface between them. A variety of tension and compression tests has been developed towards the derivation of constitutive mechanical relations for the material. This article investigates the influence of testing conditions on the carbon TRC mechanical properties and the experimental program includes pullout, tensile and compressive tests. TRC materials with four different types of coating, namely plain and sand-coated styrene-butadiene, acrylate, and epoxy were analyzed. Compression and tension tests revealed a strong influence of setup and type of coating on both properties and TRC compressive strength showed a reduction concerning the plain matrix in all cases investigated. Constitutive relations can be indirectly determined from tensile tests, including nominal bond stress, effective modulus of elasticity, and concrete tensile strength. The application of various sets of properties to the beam mechanical models and comparisons with experimental results showed tensile tests with screws of 80 mm width and 400 mm gauge length are the most suitable technique for the determination of properties to be used in moment-curvature and moment-crack opening relations.

Influence of Selected Impregnation Materials on the Tensile Strength for Carbon Textile Reinforced Concrete at Elevated Temperatures

Carbon textile reinforced concrete (CTRC) has been investigated in terms of its elevated temperature and fire behavior in order to evaluate the influence of impregnation materials. Elevated temperature tests have already been carried out for material combinations of CTRC. For the tensile strength and the bond behavior between textile reinforcement and concrete, the impregnation of the textile reinforcement is the influencing factor. Impregnation materials such as epoxy-resin (EP) or styrene butadiene rubber (SBR) showed a deterioration of the elevated temperature behavior compared to unimpregnated materials. The aim of this paper is to close the research gap on the elevated temperature behavior of carbon textile reinforced specimens impregnated with silicic acid ester, epoxy-resin, and epoxy-resin additionally surface-modified with quartz sand. For this purpose, stationary and transient tensile tests at elevated temperatures up to 1000 °C were performed. Furthermore, thermal analysis of the impregnation materials was performed to analyze the tensile tests by correlating the chemical examination with the experimental test results, and the ignitability of the reinforcements was studied using single flame tests. For the investigated reinforcement materials, the failure temperature of the specimens increases with decreasing tensile strength load level for all test specimens. In comparison to the epoxy-resin impregnation material, the silicic acid ester impregnation resulted in higher failure temperatures for comparable load levels. The decomposition of the impregnation materials proved to be a decisive factor due to comparatively evaluated thermal analysis.

Flexural behavior of layered CTRC-ECC reinforced cementitious composite plates

In this paper, three-point flexural testing was used to study the flexural properties of polyvinyl alcohol fiber-reinforced engineered cementitious composites (PVA-ECC) and carbon textile-reinforced concrete (CTRC)-layered composite plates. Taking the layer thickness of the two materials and the material type of the tensile plate surface as factors, eight research conditions were established. The effects of these factors on the cracking mode, cracking load, ultimate load, deflection, and toughness of CTRC-ECC plates were discussed. The test results show that the ultimate load and toughness of the specimen with CTRC as the tensile face are significantly larger than those of the specimen with ECC as the tensile face. C–P12–C1 has an ultimate load of 2.04 times that of P–P12–C1, C–P9–C2 has an ultimate load of 1.19 times that of P–P9–C2, and C–P6–C3 has an ultimate load of 1.30 times that of P–P6–C3. The greater the thickness of the CTRC layer is, the greater the ultimate load and toughness of the CTRC-ECC layered composite plate are. The ultimate loads of P–P12–C1, P–P9–C2, and P–P6–C3 are 39%, 157%, and 369% higher than that of P–P18–C0, respectively. When the thickness ratio of the CTRC layer to the ECC layer is two, the composite plate shows much higher toughness. The formulas were derived to calculate the flexural strength of the layered composite plate with CTRC as the tensile face, which can be used to guide the design of flexural members of layered composites.

Experimental investigation on the tensile strength degradation in curved reinforcement of textile reinforced concrete

Recently, textile reinforced concrete (TRC) has become a new approach for strengthening the existing reinforced concrete and masonry structures. When TRC wraps around the structural members, the direction of textile reinforcements changes according to the curvature radius of the structural corner. This paper presents an experimental investigation into the tensile strength degradation in curved glass and carbon reinforcement of TRC specimens. The results show that the ultimate tensile load decreases as the diameter of the semi-circle parts reduce. At the same diameter, the carbon TRC specimens have a higher tensile load-bearing capacity than glass textile-reinforced concrete. The failure modes of all the experiment cases are the fracture of the textile reinforcement in the middle of the semi-circle parts or at the transition region of the straight and curved region. The tensile strength degradation of both glass and carbon textile reinforcement has a linear relationship with the diameter of the semi-circle parts of the TRC specimens. The value only reaches up to 41% and 60% tensile strength of the individual filaments for glass and carbon fiber, respectively.

Influences of surface treatment on the mechanical performances of carbon and basalt textiles-reinforced concretes under harsh environments

The exposure to elevated temperatures and alkaline concrete pore solution can deteriorate the polymer coating in textile-reinforced concrete (TRC) and degrade its mechanical performance. To address this concern, this study experimentally investigated the influence of surface treatments on the elevated temperature resistance of carbon textile-reinforced concrete (CTRC) and basalt textile-reinforced concrete (BTRC) and durability performance in the marine environment. Three types of surface treatments, including epoxy impregnation, immersion in nano-silica suspension, and combined treatment with the silane coupling agent and nano-silica, were utilized to enhance the elevated temperature resistance and durability properties of CTRC and BTRC. The flexural strength results revealed that the modification effect of nano-silica immersion on the interfacial bonding of CTRC was greater than that of the BTRC, and the improvement can be further enhanced by using the silane coupling agent. In addition, the in-situ three-point flexural tests of CTRC and BTRC specimens were conducted under elevated temperature conditions to examine their elevated temperature resistance. It was found that exposure to elevated temperature decreases flexural performances such as first cracking strength, flexural strength, and flexural toughness of CTRC and BTRC. The elevated temperature resistance of nano-silica-treated specimens is higher than those treated with epoxy impregnation. Furthermore, the treatment with nano-silica increases the aging resistance of both CTRC and BTRC specimens in the simulated marine environment. The research outcomes can serve as a solid base for applying TRC materials in the harsh marine environment.

Study on the compression performance of RC columns confined with CTRC based on ICCP technology in chloride environment

In this paper, to study the corrosion resistance and compression performance of RC columns confined by carbon textile-reinforced concrete (CTRC) under impressed current cathodic protection (ICCP) technology in a chloride environment, a total of 30 CTRC-confined square columns were examined through axial compression tests. The effects of the parameters such as different protection potentials of ICCP technology, textile ratios, stirrup ratios, and specimen sizes on the bearing capacity and deformation performance were investigated. The experimental results indicated that the corrosion of the reinforcement in the protected specimens in a chloride environment was significantly reduced under the ICCP technology compared to the control columns. In addition, the maximum reduction in the corrosion level (mass loss degree) of the transverse and longitudinal reinforcement reached 96.43 % and 96.30 %, respectively corresponding to a potential of −0.70 V and −1.00 V. The bearing capacity and deformation performance of the CTRC-confined RC columns were significantly improved by using the ICCP technology. The maximum load and nominal effective deformation of the protected columns were increased by 29.87 % and 62.54 %, respectively, corresponding to the potential of −0.70 V. In addition, the compression performance was also found to have been affected by textile ratios, stirrup ratios, and specimen sizes. Finally, semi-empirical and semi-theoretical analytical models for predicting corrosion level and bearing capacity were established and validated through the experimental data. The proposed models exhibited a good correlation with the experimental data of CTRC-restrained RC columns subjected to axial loads under the protection of ICCP technology.

Confinement behavior and stress–strain response of square concrete columns strengthened with carbon textile reinforced concrete (CTRC) composites

In this study, with the aim of investigating the confinement behavior and stress–strain response of concrete columns strengthened with carbon textile reinforced concrete (CTRC) under a uniaxial load, a total of 20 column specimens with square cross-sections were cast and subjected to monotonic axial compression. Next, the effects of the number of textile layers, stirrup reinforcement ratio, concrete strength and short fibers on the efficiency of CTRC confining system were evaluated. The experimental results indicated that the CTRC-confined columns obtained a maximum improvement of up to 67.3% in bearing capacity and 65.2% in displacement ductility compared to the un-strengthened reference columns, and exhibited a more significant ductile failure characteristic. Moreover, the bearing capacity and displacement ductility of the confined columns were characterized by increasing with an increase in the number of textile layers and stirrup ratio, and a decrease in the concrete strength. The short fibers mixed in the strengthening layers also made a beneficial contribution to the bearing capacity and displacement ductility, particularly to the cracking load of the confined columns. Finally, a semi-empirical model was proposed to predict the axial stress and strain of concrete column specimens strengthened with CTRC based on the experimental results and theoretical analysis. The results calculated by the proposed model were evidenced to be fundamentally consistent with the experimental results. Therefore, the proposed model in this study could effectively predict the stress–strain response of square RC columns confined with CTRC composites.

Effectiveness of carbon textile reinforced concrete in shear strengthening short-span corroded reinforced concrete beams

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.

Experimental investigation and analytical modeling of the crack width effect on the fire performance of carbon textile-reinforced concrete composite

In comparison with fiber-reinforced polymer (FRP) composite, the textile-reinforced concrete (TRC) presents stability in mechanical performance at elevated temperatures thanks to a thermal protection layer by the cementitious matrix. This paper presents the experimental characterization and analytical modeling for fire performance of carbon TRC under the thermomechanical regime at constant tensile force. The carbon TRC is manufactured from the cementitious matrix with good thermal properties (refractory matrix) and the reinforcement of carbon textiles. In the experiment, the ultimate strength of the carbon TRC specimen was firstly identified from the direct tensile tests at ambient temperature. Afterwards, in the thermomechanical regime, the fire performance of carbon TRC specimens according to 5 loading levels ranging from 10% to 75% related to its ultimate strength was determined. As a result, the effect of crack appearance on this thermomechanical performance was highlighted and analyzed. For the analytical modeling, a model was calibrated with the experimental results to predict the fire performance of carbon TRC by taking into account the effect of crack width.

Reinforced Concrete Slabs Strengthened with Lap-Spliced Carbon TRC System

Construction with precast or prefabricated elements requires the connecting of structural joints. This study presents an accelerated construction method to strengthen reinforced concrete (RC) slab-type elements in flexure using precast lap-spliced textile-reinforced concrete (TRC) panels. The objectives of this study are to identify the tensile behavior of a TRC system with lap-spliced textile, and to experimentally validate the performance of the proposed connecting method by flexural failure test for the concrete slabs strengthened by TRC panels with lap-spliced textile. Twenty-one coupon specimens were tested in tension with two different matrix systems and three different lap splice lengths. The influence of the lap splice length and matrix properties on the tensile performance of the TRC system was significant. Five full-scale RC slabs were strengthened by the precast TRC panels with and without the lap splice, and was tested in flexure. The results of the failure test for the strengthened specimens showed that the ultimate load of the strengthened specimen with the TRC panel increased by a maximum of 24%, compared to that of the unstrengthened specimen. Moreover, the failure-tested specimens were re-strengthened by a new TRC panel system and tested again in flexure. The objective of the re-strengthening of the damaged RC slabs by the TRC panel is to investigate whether the yielded steel reinforcement can be replaced by the TRC panel. The initial cracking load and the stiffness of the re-strengthened specimens were significantly increased by re-strengthening.

Strengthening of Concrete Element with Precast Textile Reinforced Concrete Panel and Grouting Material.

Textile reinforced concrete (TRC) has widely been used for strengthening work for deteriorated reinforced concrete (RC) structures. The structural strengthening often requires accelerated construction with the aid of precast or prefabricated elements. This study presents an innovative method to strengthen an RC slab-type element in flexure using a precast panel made of carbon TRC. A total of five RC slabs were fabricated to examine the flexural strengthening effect. Two of them were strengthened with the precast panel and grouting material and another set of two slabs was additionally strengthened by tensile steel reinforcement. The full-scale slab specimens were tested by a three-point bending test and the test results were compared with the theoretical solutions. The results revealed that the ultimate load of the specimens strengthened with the TRC panel increased by at least 1.5 times compared to that of the unstrengthened specimen. The application of the precast TRC panel and grouting material for the strengthening of a prototype RC structure verified its outstanding constructability.

Experimental and Numerical Evaluation of Concentrically Loaded RC Columns Strengthening by Textile Reinforced Concrete Jacketing

Nowadays, Textile Reinforced Concrete (TRC) has become a very popular strengthening technique for concrete structures. This paper presents an investigation on the applicability of TRC for strengthening reinforced concrete column. Both experimental and numerical studies are conducted to evaluate the confinement effects of various TRC strengthening schemes. The experimental study is performed on a series of six reinforced concrete square columns tested to failure. Two of them were un-strengthened as references, the other four were strengthened by one or two layers of Carbon Textile Reinforced Concrete (CTRC). The results indicated that the application of carbon TRC enhanced the ductility and ultimate strength of the specimens. Failure of all strengthened columns was together with tensile rupture of textile reinforcements at the corners of column. Finite element models of the CTRC strengthened columns based on ATENA software package were developed and verified with the experimental results. The analytical results show that in the specimen corner areas, textile reinforcements are subjected to a 3D complicated stress state and this may be the cause of their premature failure.

Flexural and Shear Behavior of Reinforced Concrete Beams Strengthened with Carbon Textile Reinforced Concrete

Flexural and Shear Behavior of Reinforced Concrete Beams Strengthened with Carbon Textile Reinforced Concrete

Carbon textile reinforced concrete: materials and structural analysis

Textile reinforced concrete (TRC) is a composite made of a cementitious matrix and non-corrosive fabrics with excellent mechanical behavior and elevated load-bearing capacity. Therefore, TRC is highly recommended for structural applications. Due to the reinforcement’s non-corrosive property, this material is interesting in replacing the reinforced concrete (RC). This work presents a study on the characterization of carbon TRCs under tensile and bending loadings. Direct tensile tests were performed and the effect of the polymeric coating used on the fabric manufacturing, the number of layers and an epoxy resin and sand coating was analyzed. The results showed that the composites mechanical behavior depends mainly on the reinforcement-matrix bond. In order to evaluate the fabric-matrix interface, pull-out tests were carried on. The TRC potential as a structural application is also addressed. Thus, structural beams reinforced with carbon TRC with and without dispersed steel fibers on the matrix were submitted to bending. Compared with RC, the TRC beams presented less ductile behavior. Nevertheless, the current standards for the concrete structures design establish a maximum element displacement of span/250. At this level, the load–displacement curves of TRC and RC beams were coincident, and the applied load was considerably distant from the failure load.

Mesoscale experimental investigation of thermomechanical behaviour of the carbon textile reinforced refractory concrete under simultaneous mechanical loading and elevated temperature

In comparison with carbon fiber reinforced polymer material, the carbon textile reinforced concrete (TRC) is usually coted to have a better fire behaviour. The aim of this paper is to analyse the elevated temperature behaviour of TRC. This paper presents the experimental results conducted on carbon TRC at mesoscale in the range of temperature from 25 °C to 700 °C. The carbon TRC consists of refractory matrix and carbon textile which has been treated with amorphous silica products for a good bond with the cement matrix. As a result, carbon TRC showed the strain-hardening behaviour with different phases and brittle behaviour depending on the temperature. The evolution of carbon TRC properties with elevated temperature (the ultimate stress, the crack stress, the initial stiffness) was experimentally identified. The mechanical property evolution of carbon textile and refractory concrete (the ultimate strength, the Young’s modulus) depending on temperature was also presented. The thermal tests on carbon TRC cylinder specimens were also performed to identify the diffusivity coefficient of this composite. All results obtained were analyzed in order to find the contribution of carbon textile and refractory matrix to fire resistance of carbon TRC. Its ultimate strength has been improved about 2 times compared with non-reinforced matrix at elevated temperature ranging from 25 °C to 400 °C. The efficiency coefficient of carbon textile could be calculated in this study.