Textile Reinforced Concrete Layers Research Articles

Compressive behaviour of concrete columns confined with textile reinforced concrete composites

The enhancement of strength and deformation capacity in confined concrete members could be achieved through the application of advanced composite materials. Textile reinforced concrete (TRC), a novel cement-based composite material, is considered as a viable alternative to fiber reinforced polymer (FRP) sheets, addressing the limitations associated with organic resins. This study delved into the impact of various parameters, such as cross-section shapes, concrete strengths, and the number of TRC layers, on the confinement effect. The results reveal a consistent augmentation in both axial compressive strength and deformation capacity of confined concrete with an escalation in the number of TRC layers, irrespective of the cross-sectional configurations. Notably, the maximum enhancements in axial peak stress for rectangular, square, and circular specimens are recorded at 45.96 %, 49.98 %, and 90.06 %, respectively, accompanied by corresponding increases in axial strains of 56.28 %, 53.74 %, and 86.00 %, respectively. The effectiveness of TRC confinement exhibits a substantial correlation with the geometry of the cross-sections. The circular ones have higher utilization rates followed by the square ones, and the rectangular ones with section aspect ratio greater than 1.0 have the lowest utilization rates. Furthermore, an evaluation of existing confinement identification models indicates that both the Mirminan Model and Wu Model could effectively delineate the hardening and softening characteristics of circular and rectangular specimens. However, there exists scope for improving the accuracy of these models. Therefore, a novel modified identification model, predicated on the Mirminan model, was proposed to refine the confinement assessment process. The revised modified confinement ratio (MCR) is recommended at a value of 0.045, aiming to elevate the precision and reliability of confinement evaluations in concrete structures.

Experimental and numerical evaluation of axial compression strengthening for corroded square reinforced concrete columns by carbon textile reinforced concrete

This research focuses on analyzing the behavior of reinforced concrete (RC) columns under axial compression, both in their uncorroded and corroded states, through a combination of experimental and numerical investigations. For the experiment, seven specimens were prepared and manufactured subjecting to centric compression. The cross-sectional side length of the square columns was 200 mm. The column height was selected as 800 mm based on the dimensions of the testing machine. The specimens were divided into three groups: (i) the control columns, (ii) the corroded columns without strengthening, and (iii) the corroded columns strengthened with an external carbon textile reinforced concrete (TRC) layer. The experimental results showed that when the corroded columns had approximately 10% mass loss in longitudinal reinforcement and stirrups, the ultimate load was reduced by 5.7%. Meanwhile, the axial compression capacity of corroded columns strengthened by TRC layer was approximately 28% higher than the corroded unstrengthened ones. All tested specimens failed due to the buckling of the longitudinal reinforcement. The strengthened columns failed at the corners due to the rupture of the textile reinforcement. To validate the experimental results, a finite element (FE) modeling was presented.

Flexural Durability and Chloride Diffusion Equation of TRC-Strengthened Beams under a Chloride Environment

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.

Performance of interface between TRC and existing concrete under a chloride dry-wet cycle environment

Textile-reinforced concrete (TRC) is suitable to repair and reinforce concrete structures in harsh environments. The performance of the interface between TRC and existing concrete is an important factor in determining the strengthening effect of TRC. In this paper, a double-sided shear test was performed to investigate the effects of the chloride dry-wet cycles on the average shear strength and slip at the interface between the TRC and existing concrete, also considering the existing concrete strength, bond length, textile layer and short-cut fiber arrangements. In addition, X-ray diffraction (XRD) technology was used to analyze the microscopic matter at the interface in the corrosive environment. The experimental results indicate that the interface performance between TRC and existing concrete would decrease with continued chloride dry-wet cycles. Compared with the specimen with a single layer of textile reinforcement, the specimens with two layers of textile with added PVA or AR-glass short-cut fibers could further improve the properties of the interface between the TRC layer and existing concrete. For the TRC with a single layer of textile, the average shear strength tended to decrease with increasing bond length. In addition, the strength grade of the existing concrete had a minor effect on the interface properties.

Experimental study on flexural and shear behaviour of sandwich panels using glass textile reinforced concrete and autoclaved aerated concrete

Textile-reinforced concrete (TRC) is a new composite material made of high-strength textiles embedded within fine grained concrete (FGC). The application of TRC leads to the design of thin and slender structures or for repairing and strengthening of existing structural members. Autoclaved aerated concrete (AAC) is an ultra-lightweight concrete, which can be combined with high strength TRC to form some kinds of precast curtain panels in construction. The concept of the TRC-AAC panel is based on the theory of sandwich construction with strong and stiff skins, like TRC layers, bonded to a lightweight AAC core. The resulting hybrid TRC-AAC panel can be used as structural or non-structural member for the housing construction. In this paper, the flexural and shear performance of hybrid TRC-AAC sandwich panels is presented by means of experimental results. The sandwich panels use three layers of different materials: TRC for the tensile layer, AAC for the core material and FGC for the compressive layer. Three different types of glass textile were used as reinforcements in the TRC layers.

Lightweight TRC sandwich panels with sustainable diatomite-based core for energy retrofitting of existing buildings

ABSTRACT Precast sandwich panels, characterized by external textile reinforced concrete (TRC) layers and an inner insulation core, represent a convenient system for energy retrofitting of existing façades. These elements fulfil all the requirements for façade systems and constitute a valid alternative to both external thermal insulation composite systems (ETICS) and ventilated façades. The main feature of this kind of panel is that it could be applied on an existing façade through four punctual connectors by means of a crane, without any scaffolding. The paper provides a solution that has been firstly designed within the European project ‘EASEE’ and it is now being developed in the ‘Smart P.I.QU.E.R.’ project, supported by Lombardy Region (Italy). Basing on the experience gained in the European project, the partners are trying to overcome some criticisms previously encountered, related to the use of expanded polystyrene as insulation material, the cost of the anchoring system and aesthetical issues related to TRC cracking. The main innovations concern: the development of a new eco-friendly insulation material based on inorganic diatomite; the optimization of TRC layers; the development of a new anchoring system. This paper focuses on the research developed at the material level referring to both external layers and insulating core.

Study on the compression performance of small eccentric degradation columns strengthened with TRC in a chloride environment

To explore the mechanical properties of small eccentric compression degradation columns strengthened with textile-reinforced concrete (TRC), the effects of using different numbers of textile layers and the degree of corrosion mass loss on the TRC reinforcement were studied. The results showed that compared with non-corroded columns, the brittle characteristics of the electrified corrosion column were more obvious, and the strengthening effect of the TRC was improved. These characteristics provided good resistance to chloride corrosion and restraint effects for strengthening the columns. The bearing capacity of the corroded column increased after being reinforced with a TRC layer. However, as the number of reinforcing layers increased, the increase in the bearing capacity decreased. When the number of TRC reinforcement layers increased to three layers, the damage pattern of the corroded column changed, and the damage position moved from the upper part of the column to the central region of the column. Finally, the ultimate bearing capacities of the small eccentric compression columns strengthened with TRC in dry-wet environments with chloride salt were calculated, and the calculation model was given.

Capillary transport of water through textile-reinforced concrete applied in repairing and/or strengthening cracked RC structures

The use of textile-reinforced concrete (TRC) has great potential for innovative solutions in repairing, protecting, and strengthening concrete and RC structures. The article at hand reports on an investigation on composite concrete specimens made of cracked ordinary concrete as substrate and textile-reinforced concrete (TRC) as a cover layer for its strengthening and repair. The TRC cover layer was assessed with regard to its effectiveness as a protective layer against the ingress of water through capillary action. Since in real applications such TRC layers may be cracked or presumed to be so, thereby activating the load-carrying function of the textile reinforcement, the TRC layer was cracked for purposes of this study. The water transport in the cracked ordinary concrete specimens without the TRC layer was used as a reference. Gravimetric measurements and neutron radiography served as the testing techniques. In ordinary concrete quick and deep ingress of water through relatively wide macro-cracks of approximately 100μm width, followed by transport through the capillary pore system, caused saturation of large areas in a rather short time. TRC applied to the RC surface reduced the ingress of water to a large extent. Its small crack widths of 15 to 20μm changed suction behaviour fundamentally. In the cracked substrate of ordinary concrete, capillary suction was prevented, and transport through the pore system of the matrix became the prevailing transport mechanism of capillary action. Not only was the mechanism altered, but the transport of water deep into inner regions was markedly retarded as well.

Properties and calculation of normal section bearing capacity of RC flexural beam with skin textile reinforcement

In order to overcome the wide crack of ordinary reinforced concrete (RC) at service stage which affects the service performance and durability of structures, a kind of concrete structure with skin textile reinforcement is proposed, namely a part of concrete cover of RC members is replaced by textile reinforced concrete (TRC). The flexural experimental results indicate that when the reinforcement ratios of steel bars are constant, compared with control beams, the average value of crack loads of the beams, whose reinforcement ratios of textile are 0.018%, 0.036% and 0.055%, increases by 15.5%, 20.4% and 31.1%, respectively, the average value of yield loads respectively increases by 12.5%, 19.9% and 21.1% and the average value of ultimate loads respectively increases by 8.5%, 26.0% and 44.0%, respectively. Considerable reduction in cracks width and spacing is observed for specimens with a TRC layer, and when the beams yield, the maximum crack width of the beam with textile stuck no sand and the beam with textile stuck sand is reduced by around 60% and 70%, respectively. Surface treatment of textile and mixing polypropylene fiber into fine grained concrete contribute to enhance the service performance of the flexural element. Embedding U-shaped hoop has almost no effect on the control of the crack width. Finally, the calculation method of ultimate bearing capacity of this flexural component with TRC layer was presented. Comparison between the calculated and the experimental values reveals satisfactory agreement, and the maximum error is no more than 6%.

Strengthening concrete elements by confinement within textile reinforced concrete (TRC) shells – Static and impact properties

In this paper the mechanical behavior under static and impact loading of concrete elements strengthened with shells of textile reinforced concrete (TRC) made of carbon, alkali-resistant glass and polyethylene fabrics is presented. Testing of the strengthened elements for flexure by static and impact loading showed that the TRC reinforced elements exhibited an improvement in load capacity, energy absorption and impulse absorption. The improvement in static loading was found to be higher than in impact loading. The carbon TRC layers provided the greatest improvement and the polyethylene TRC layers the smallest. These results correlate well with the behavior of the TRC shells and with the properties of the fabrics themselves.

Flexural Behavior of Reinforced Concrete Beams with TRC Tension Zone Cover

This research makes a further contribution to the existing knowledge regarding textile-reinforced concrete (TRC) structural members, and the proposed component combines the advantages of TRC and reinforced concrete (RC). This concrete member was experimentally studied and its analytical formulae were derived. Test results of the flexural experiment study indicated that the beams with the TRC layer had some increases in the first crack load, the yield load, and the ultimate moment capacity, compared with the ordinary RC beams, and furthermore the ultimate moment capacity had significant increases with the increase of the reinforcement ratio of textile. A considerable reduction in the crack width and spacing was also observed for the beam with a TRC layer, and thus the postcracking stiffness of the beam was improved. Furthermore, this concrete member has satisfactory flexural ductility. For a single reinforced concrete beam with a rectangular cross section, two types of limit failure states are presented with respect to different reinforcement ratio of textile, and for each state, the relationship between the reinforcement ratio of textile and the reinforcement ratio of steel bar is derived. The calculation methods for the ultimate moment capacity for three failure modes and the midspan deflection during the entire loading process are also presented. A comparison between the calculated and the experimental results reveals a satisfactory agreement and verifies the feasibility of the formulae.

Permeation of water and gases through cracked textile reinforced concrete

Textile reinforced concrete (TRC) is a high-performance, cement-based composite consisting of fine-grained concrete and textile reinforcement, the latter usually consisting of glass or carbon multi-filament yarns. When subjected to tensile loading, TRC shows pronounced strain hardening behaviour accompanied by multiple cracking. The superior mechanical performance of TRC can be used very efficiently in the strengthening and repair of structural elements made of reinforced concrete or other traditional materials. The durability of restored structures with such TRC layers depends directly on the resistance of TRC to the transport of fluids and gases into and through the repair material. In this experimental study the effects of multiple cracking on the permeation of water and gases through TRC are investigated. For permeability testing special equipment was developed to facilitate in situ measurement of the water and gas transport properties of cracked TRC at chosen strain levels under uniaxial tensile loading. Further parameters of the study were the fineness and coating of the yarns comprising the textile reinforcement. In the case of uncoated textile, an increase in the fineness of the yarns as well as the residual strain led to a considerable increase in water absorption. The permeation of oxygen and water through cracked TRC correlated with the induced strain and the crack characteristics, i.e. the number of cracks and crack width. The crack pattern itself depended on the choice of the particular textile reinforcement. The influence of imposed strain on the permeation of water in cracked TRC was described by a simple model based on Hagen–Poiseuille’s Law. Furthermore, the effect of self-healing phenomena on the transport properties of TRC was investigated. The self-healing of fine cracks led to a very pronounced reduction in the transport rates over time.

Numerical design approaches of textile reinforced concrete strengthening under consideration of imprecise probability

The paper focuses on numerical approaches valuable in the design of strengthening layers made of textile reinforced concrete (TRC) applied on surfaces of RC structures. The presented methods aim at the design of structures that are components of significant buildings, e.g. power stations, historic valuable buildings and life lines. The generally existing uncertainty of material and geometry parameters of the RC structures and the TRC layers is modelled by imprecise probability. Reliability, lifetime and robustness are assessed by means of generalised uncertainty measures and considered as design objectives or constraints. Three computational methods are developed for the computation of preferential designs under consideration of imprecise probability. The methods are applied for the design of a porch roof strengthening comparing the robustness of different variants and for the reliability-based design of a T-beam strengthening.