Concrete Canvas Research Articles

Experimental study on the axial compressive mechanical performance of concrete short columns jointly confined with CC and CFRP after sulfate attack

By conducting axial compression tests on square concrete columns jointly reinforced by concrete canvas (CC) and carbon fiber-reinforced polymer (CFRP) after sulfate attack, the influences of the number of CFRP layers, the degree of erosion (number of wet and dry cycles) and the number of CC layers on the mechanical properties under axial compression were researched, and the failure morphologies, bearing capacities and deformation capacities of square concrete columns with joint reinforcement were analyzed. The results showed that sulfate attack would change the internal structure of the concrete, reduce the deformation capacities of the specimens, and make the brittle characteristics obvious. The square concrete column confined by CFRP after sulfate attack caused brittle damage to the specimen without obvious warning due to the stress concentration at the corner. The introduction of CC could relieve the corner stress concentration, improve the utilization of CFRP, avoid failure due to local destruction, and effectively improve the failure morphologies of the specimens so that the specimens had obvious precursors at failure. Based on the experimental study, the calculation model of the bearing capacity and the strain‒stress model of the square concrete column jointly confined by CC and CFRP after sulfate attack were established.

Optimization of mechanical property and microstructure for magnesium phosphate cement-based canvas using borax

As a type of excellent rapid protective material with fast hardening and high early strength characteristics, magnesium phosphate cement (MPC) is used as the cementitious material to fabricate concrete canvas. For a thick MPC canvas, sufficient hydration reaction is crucial in keeping its integrity. Borax is used to adjust the hydration progress of MPC in warp-knitted fabrics. The effects of different borax contents (0 %, 1 %, 2 %, 3 %, 4 %, 5 %, 6 %) on the compactness of reaction products and the mechanical properties of MPC canvas are evaluated. In addition, SEM, XRD, hydration heat, and X-CT are used to systematically analyze the hydration morphology, products, exothermic process, and pore structure of MPC canvas. The results show that borax can effectively delay the setting time of MPC, addressing the issue of incomplete hydration of MPC powder in thick canvas. The 4 % borax content (B4 sample) can ensure the complete reaction in a 20 mm thick MPC canvas, achieving the maximum compressive and flexural strengths of 26.37 MPa and 4.9 MPa at 7 d, respectively. Borax effectively optimizes the pore structure of MPC canvas and achieves a dense bond at the interface between MPC and the canvas fabric with the minimum porosity of 11 % in the B4 sample. Therefore, borax is crucial for ensuring the structural integrity of MPC canvas.

Flexural behaviour and strengthening of reinforced concrete beams using concrete canvas

Flexural behaviour and strengthening of reinforced concrete beams using concrete canvas

Composite Materials as the Basis of Concrete Canvas

Statement of the problem. Composite materials based on mineral components and organic and mineral systems are gradually expanding their presence in the domestic market of materials and building techno-logies. Concrete fabric, as one of the varieties of textile-concrete, can be considered as a composite material whose properties depend both on those of polymeric materials that form its enclosing surfaces and those of the core material, and on the nature of the interaction between the facing and core materials. The purpose of the research presented in the article is to evaluate the main strength characteristics of the concrete canvas, as well as to study the effect of the content of Portland cement, plasticizer and modifying additive on the properties of fine-grained concrete as the basis of the concrete canvas, as well as to evaluate the possible areas of application of the concrete canvas with the obtained properties. Results. In the process of processing the results of the experiment and analytical optimization of the response functions, the fundamentals of the methodology for selecting the composition of modified fine-grained concrete as the basis of the concrete canvas were developed. As a result of the tests, the following characteristics of the material were established: average density ––1450––1500 kg/m3; compressive strength –– not less than 36––38 MPa, puncture strength –– not less than 3 kN; ultimate strength in ben-ding 16––20 MPa. Conclusions. Despite the fact that the thickness of the concrete canvas in the hardened state does not exceed 10 mm, its properties are not inferior to those of other types of textile concrete, i.e., they have high strength characteristics with a relatively small thickness. The most promising areas of application of the concrete canvas are the repair and waterproofing of reinforced concrete structures of hydraulic structures, and the strengthening of slopes.

Experimental and numerical study of G-HPC slabs rapidly repaired by G-HPC canvas and G-UHPC under contact detonations

The rapid repair of engineering structures damaged due to explosions can enhance the structural impact resistance after an explosion, thereby reducing the potential for casualties and property losses. A novel concrete canvas was firstly proposed based on G-HPC (geopolymer-based high performance concrete), UHMWPEWF（ultra-high molecular weight polyethylene woven fabric), and 3D BFG (basalt fiber grid) to rapidly repair engineering structures and render their blast resistance. A sequence of contact blast tests was systematically conducted to verify the feasibility of the proposed G-HPC canvas. A normal reinforced concrete slab and a steel-wire mesh (SWM) reinforced G-HPC slab were initially damaged by the contact blast loading, afterwards, the damaged concrete slabs were rapidly repaired by G-UHPC (geopolymer-based ultra-high-performance concrete) and the novel G-HPC canvas. The rapidly repaired concrete slabs were subsequently tested by contact blast loading. A precise 3D finite element model was then developed and calibrated based on the experimental results. Eventually, numerical simulations were performed to better understand the contribution of main parameters including repair materials filling the internal slab, steel-wire mesh, G-HPC canvas location and its thickness towards the improvement of the rapidly repaired slabs against the contact blast loading. The experimental and numerical results indicated that the SWM reinforced G-HPC slab has superior blast-resistance compared with the RC slab and the proposed method to rapidly repair the damaged slabs was feasible. The G-HPC canvas should be placed properly since the location of the G-HPC canvas is related to whether fragments are produced on the rear surface of the damaged slab. Increasing the G-HPC canvas thickness and the layers of SWM could significantly reduce the damage area of the repaired slab.

Study on Axial Compression Performance of Corroded Reinforced Concrete Columns Strengthened by Concrete Canvas and Carbon Fiber Reinforced Plastic under Secondary Corrosion

To investigate the effects of concrete canvas (CC) and carbon fiber reinforced plastic (CFRP) reinforcement on the mechanical properties of corroded reinforced concrete columns (compressive strength, flexure strength, strength of extension, and so on), 42 columns in four groups were designed and axial compression experiments were carried out. For the corroded reinforced concrete columns reinforced with CC and CFRP, the effects of initial corrosion rate (5%, 10%), secondary corrosion time (15 d, 30 d), number of CC layers (0, 1), and number of CFRP layers (1, 2, 3) on the failure morphology, load carrying capacity, and ductility of concrete columns were analyzed. The test results show that the properties of the single layer CC confined specimens are improved to a certain extent, and the ductility properties are enhanced. The properties of the CC–CFRP composite constrained specimens are greatly improved, the plastic deformation ability is enhanced, and the typical ductile damage characteristics are shown. The corrosion inhibition of CC for specimens with a theoretical corrosion rate lower than 20% showed an increasing trend, and the corrosion inhibition rate ranged from 23.0% to 31.2%. CC and CFRP restrain the concrete jointly, hindering the expansion inside the concrete, and the peak strain of the joint restraint specimen itself changes greatly, while the overall peak strain of the corrosion specimen is very small under the action of the joint steel bar. Finally, according to the existing peak stress–strain model and the experimental data in this paper, a peak stress–strain model suitable for corroded reinforced concrete columns is established. The established calculation model has a high accuracy, which provides a certain theoretical basis for subsequent research.

Flexural strengthening of RC beams by advanced concrete canvas

AbstractIn this study, concrete canvas (CC) layers were used as a novel method to strengthen reinforced concrete (RC) beams because of their flexibility, rapid installation, fast curing, and rapid strengthening. Due to the importance of the CC mechanical properties, various combinations of cement including ordinary (OPC) and High Alumina (HAC), as well as silica fume, were investigated to determine the optimal mixture for strengthening RC beams. The results indicate that substituting 75% of HAC with OPC significantly boosted flexural strength by 33%, and increased tensile strength in the warp and weft directions by 25% and 21%, respectively. The study examined six RC beam specimens in a four‐point flexural test, assessing their flexural properties, ductility, cracking behavior, and energy dissipation. The number of CC layers and the bonding method, which involved either the conventional externally bonded reinforcement (EBR) technique or the externally bonded reinforcement on grooves (EBROG) technique were studied. The experimental results revealed the superiority of the EBR method over the EBROG technique due to the uniform bond between CC and the concrete surface. Using the EBR technique, improvements of 35% and 51% were observed in the load‐carrying capacity of the beams strengthened with one and two CC layers, respectively. It is while for the beam with an improved loading capacity of 51%, the crack width decreased from 5.3 to 2.1 mm, and the energy dissipation increased by three times compared to the control specimen. Theoretical analysis also was performed to calculate the load‐carrying capacity of the RC beams strengthened with CC layers.

Advantages of using CONCRETE CANVAS materials in railway track construction

Purpose. Justification of the feasibility of using new types of drainage materials, such as Concrete Canvas (CC), under the upper structure of the railway permanent way. Methodology. The tasks were solved by a complex research method, including analysis and generalization of literary and patent sources, analytical, experimental studies, using computer and mathematical modeling methods. Tests were conducted with and without the CC layer in a multi-level shear box. After the shear test, the specimens were also tested for load-bearing capa­city (E2, according to the Hungarian standard) and particle breakage. The contact surface between the bottom of the ballast and the CC was measured using a precision 3D laser scanner (GOM ATOS) and visualized graphically using AutoCAD software. Findings. Experimental testing of the vertical load during connection and analysis compared with the test results of geocomposite/geogrid structures, internal shear resistance, and other parameters proved the structure’s higher load-bearing capacity with the CC layer. Based on the results, the Concrete Canvas structure provides higher reinforcement than the average geogrid type. Originality. The advantages of using new Concrete Canvas materials in the structure of a railway track have been demonstrated for the first time to provide greater internal shear resistance than the average for geogrids. Practical value. These results may provide primary data for using Concrete Canvas in railway tracks and superstructures in the future.

Mechanical performance of concrete canvas reinforced with insert-bar structures under quasi-static and impact loading

Concrete canvas (CC) is a promising composite based on a combination of three-dimensional fabric and cement-based powder, with the comprehensive advantages of easy storage and transport, convenient construction, rapid strength development, and low dust pollution. In civil and military engineering, interest and exploration work within the field of CC have been ongoing for many years. While external measures exist to enhance the mechanical properties of CC, substantial internal measures are still lacking. In this paper, an internal stiffening strategy was proposed by coupling warp-knitted spacer structure with a series of insert-bar structures, attempting to improve the mechanical performance of CC. The reinforcing effect of flexible bar stiffeners were investigated through quasi-static bursting test and impact test. Damage morphology analysis was then performed to reveal the progressive failure mechanism. The obtained results demonstrated that flexible bar stiffeners with low modulus were highly beneficial reinforcements for CC due to their favorable synergy and great stress dissipation capacity. The load-bearing capacity and toughness of CC were increased with the insertion height and groups of bar combination. The vertical combination could further enhance the penetration resistance by altering stress transfer.

Behavior of high-performance concrete canvas Miura-origami structures under flexural loading

Rapid construction and reducing building weight have been the favorite objectives of civil engineers in recent years. Canvas concrete is a promising material for rapid construction in which 3D spacer fabric is used for reinforcement and Origami construction has attracted attention for its structural efficiency and low weight in addition to its architectural aspects. The present study investigated the behavior of folded plates with origami patterns made of canvas concrete. The Miura pattern was used as the origami structure that was combined with high-performance concrete reinforced with 3D spacer fabric. Three Miura models were constructed as both non-sandwich and the core of the sandwich specimens. The specimens were subjected to four-point flexural loading, which showed that the Miura models with the same amount of materials increased the load-bearing capacity of a structure. By comparing specimens, the Miura patterns with sharper angles provided greater load-bearing capacity, energy absorption, and maximum load/weight ratios.

Alkali-activated slag mortar molded by non-stirring molding: Compressive strength, hydration properties and microstructures

Alkali-activated slag (AAS) characterized by fast hardening and high early strength has potential application prospects in concrete canvas (CC), where a non-stirring molding method is required to prepare mortar. This paper provides a new method for the preparation of alkali-activated slag mortar (AASM) by non-stirring (sprinkling-molding), where mechanical properties, hydration properties, and microstructures were investigated. The results suggest that the compressive strength of the sprinkling-molding mortar was slightly lower than that of the conventional stirring-molding mortar, and the compressive strength with sodium silicate content of 15 % the slag mass at 28d can reach 44.5 MPa. The hydration products are dominated by amorphous C-A-S-H gels, with small amounts of hydrotalcite. There are differences in degree of hydration and microstructures of each layer in the sprinkling-molding mortar.

Inner shear resistance increasing effect of Concrete Canvas in ballasted railway tracks

Purpose. To prove that the GCCM (geosynthetic cementitious composite mat) – type Concrete Canvas (CC) – is an adequate supplementary layer on the top of the subgrade. As its drainage function is known, this article tries to prove the reinforcement possibility. This layer is relatively thin; nevertheless, it can behave like the geogrids. It is the main path to finding out the opportunity of the interlocking effect and its impact on the railway ballast’s inner shear resistance. Methodology. The laboratory measurements were performed in a multi-level shear box, which allows simulating the multi-level shift of the ballast layer. The tests were planned with and without the CC layer. After shearing, the samples were also tested for load-bearing capacity (E2; according to the Hungarian Standard) and particle breakage. On the other hand, the contact surface between the lowest part of the ballast and CC was also measured by a sophisticated 3D laser scanner (GOM ATOS) and graphically by AutoCAD software. Findings. After the results of the laboratory experiments are analyzed, the following parameters are calculated and determined: 1) the reinforcement ratio as the tangent of the inner shear resistance curves in the 5–15 mm horizontal shearing interval as well as the area under graphs by integration in the 0–40 mm interval; 2) the change in load-bearing capacity of the layer-structure with and without CC; 3) the amount of the cement particles; 4) the amount of the broken particles; 5) contact surface between the lowest layer of ballast and CC; 6) flatness of CC sheets after shearing. Based on the results, the Concrete Canvas provides significant reinforcement to the railway ballast. Originality. Any other type of measurement with Concrete Canvas in a multi-level shear box is unknown. The topic is unique. Practical value. In the future, these results may provide baseline data to verify the suitability of the Concrete Canvas in the railway sub- or superstructure for various types of transport.

Experimental study on the mechanical properties of concrete canvas and CFRP jointly confined circular concrete columns under axial compression

Concrete canvas (CC) has good corrosion resistance and fire resistance, but it is rarely used in civil engineering. In this study, CC and carbon fiber-reinforced polymer (CFRP) are jointly used to reinforce concrete columns (i.e., jointly confined specimens) to expand their engineering application. To explore the axial compressive performance of combined CC-CFRP confinement concrete columns, 13 sets of specimens were designed in this study based on the number of CFRP layers, number of CC layers and volumetric stirrup ratio. The conclusions are as follows: 1) based on acoustic emission (AE) technology, the presence of CC can improve the uneven deformation of the concrete, and the jointly confined specimen has better energy dissipation capacity; 2) based on the experimental data, the peak stress of the jointly confined specimen is reduced by up to 10% compared with the CFRP-confined specimen (i.e., the single confined specimen), and the ultimate strain is increased by at least 56.2%, which shows that the jointly confined method is reasonable and feasible; and 3) the peak stress and ultimate strain models of the jointly confined specimen are obtained by numerical fitting, and a stiffness-based design-oriented compressive stress–strain model for the jointly confined specimen is proposed. Compared to existing models, the proposed model has higher accuracy, which can provide a theoretical basis for further research.

Examination of Concrete Canvas under Quasi-Realistic Loading by Computed Tomography

The current paper concerns the investigation of CC (Concrete Canvas), a unique building material from the GCCM (geosynthetic cementitious composite mat) product group. The material is suitable for trench lining, trench paving, or even military construction activities, while the authors’ purpose is to investigate the application of the material to road and railway substructure improvement. This research was carried out to verify the material’s suitability for transport infrastructure and its beneficial effects. The authors’ previous study reported that the primary measurements were puncture, compression, and the parameters evaluated in four-point bending (laboratory) tests. However, based on the results, finite element modeling was not feasible because the testing of the composite material in a single layer did not provide an accurate indication. For this reason, the material characteristics required for modeling were investigated. A unique, novel testing procedure and assembly were performed, wherein the material was loaded under quasi-realistic conditions with a crushed stone ballast sample and other continuous particle size distribution samples in a closed polyethylene tube. In addition, the deformation of the material following deformed bonding was measured by computed tomography scanning, and the results were evaluated.

Mechanical properties of short concrete columns reinforced with carbon fiber reinforced composite strips and concrete canvas under axial compression based on acoustic emission

To study the mechanical properties and failure mechanism of short concrete columns reinforced with carbon fiber reinforced polymer (CFRP) strips and concrete canvas (CC), 38 short concrete columns with variable CFRP strip width, number of CFRP layers, and section form and with and without reinforcement bars were subjected to axial compression, and the damage of the strengthened specimens was monitored with acoustic emission (AE) technology. The test results show that the strength and ductility of the reinforced specimens are increased by 59–96 % and 108–126 %, respectively over those of the unreinforced ones. Reinforcement bars and concrete strength grade have little impact on the bearing capacity of the jointly reinforced specimens. The constraint effect of CC increases with increasing CFRP strip width. The columns form strong and weak constraint areas that correlates with the areas wrapped with strips and not wrapped with strips. With increasing strip width, the energy released when the specimen fails increases, and the ductility increases. These data are used to establish a strength calculation model for a short concrete column constrained with CFRP strips and CC. This model shows high fitting accuracy with the test results and can be used as a reference for practical reinforcement projects.

Flexible canvas produced from uncured-natural rubber composites filled with high calcium oxide fly ash/cement hybrid filler

Concrete canvas (CC) is an attractive composite based on a combination of textile and cement, applying for the slope protection and ditch lining. However, there is no binder between both the materials and its high thickness causes a strong detachment of cement particles, and the complex designing of CC shapes is limited. Therefore, the possibility of incorporating natural rubber (NR) as a binder for extending the applications of cement-based composites has been considered. In the present work, NR composites with fly ash (FA) and cement (CM) are prepared through an internal mixer and a two-roll mill with a total filler concentration of 1000 phr. It can be found that, FA/CM hybrid filler is successfully adhered together through the NR matrix, and it promotes the flexible canvas composites with controlled thickness and provides complex shapes. The existing calcium oxide (CaO) present in the filler reacts with water molecules, and the NR composites become hardened and restrict the deformation and decomposition. The optimum ratio of FA/CM hybrid filler has been fixed at 300/700 phr, which has recognized as the product-like concrete canvas. Tensile properties, dynamic properties and thermal stability are improved upon the incorporation of hybrid fillers and its flexibility is found to be sustained on soaking with water. The structural changes are confirmed from the infrared spectrum which clearly explains the transformation of CaO to the CSH network structure in the NR composites. Un-crosslinked composites exhibited similar mechanical properties compared to the chemically crosslinked NR with sulfur curing system. Thus the composites can be used as the flexible canvas, although it has not been vulcanized. To clarify this statement, tensile properties, abrasion resistance and bending propagation of NR composites, NR vulcanizates and commercial concrete canvas are compared. The composites exhibited comparable properties with superior flexibility performance. Along with the waste utilization, the uses of FA, provides an opportunity of using FA/CM as the flexible canvas.

Review on the design and application of concrete canvas reinforced with spacer fabric

Concrete canvas reinforced with spacer fabric has increasingly gained popularity due to its lightweight, great flexibility, high strength and low contamination compared to ordinary concrete. In order to fully explore the structure and performance of this novel composite, this review illustrates how to design high-performance concrete canvas and presents a summary of recent application status of it. Firstly, the structure and properties of knitted and woven spacer fabric and concrete material that comprise concrete canvas is introduced. Secondly, internal and external mechanisms affecting the properties of concrete canvas have been described. To illustrate how to evaluate and test the mechanical behavior of concrete canvas, typical mechanical experiments such as tensile and flexural experiment and failure mechanisms are explained. In terms of the characteristics of concrete canvas, the present article reviews current applications of it in disaster relief tent, slope protection, ditch lining and furniture design areas. Nevertheless, its practical applications are still in the preliminary stage, it is of great necessity to expand its application from the point of view of replacing traditional materials, changing structural design, external reinforcement and perfecting performance evaluation system.

Acoustic Emission Assessment of Corroded RC Columns Jointly Reinforced with Concrete Canvas and CFRP

To explore the crack behaviors of corroded concrete columns jointly reinforced by concrete canvas (CC) and carbon fiber reinforced polymer (CFRP), a total of six specimen sets with different reinforcement forms and corrosion rates are designed and tested by acoustic emission (AE) technology. The assessed methods are AE characteristic parameters, RA-AF values, b values, and AE event spatial location map. The results show that the presence of CC changes the failure morphology of the specimen and improves the uneven deformation of concrete in the core area, which proves that the jointly reinforced method exhibits high plasticity deformation ability. The crack mode of the jointly reinforced specimen undergoes multiple transformations between tensile cracks and shear cracks, before ending in the final crush failure. The fluctuations in both amplitude and frequency of the b values of the jointly reinforced specimens increase significantly with time. The crack activity of concrete is more intense in this period, which proves that the jointly reinforced method ensures a more complete failure. Moreover, the increases in corrosion rate reduced the probability of shear cracks in the core concrete and further increased the failure degree of the specimen. The present study demonstrated that AE monitoring can effectively capture the characteristics of the cracking process of jointly reinforced concrete.

Development of adaptive technologies for the operation of irrigation canals covered with a concrete canvas

The relevance of the study is to expand and obtain new theoretical knowledge on the application of adaptive technologies of irrigation canals operation depending on the type of facing materials, namely geosynthetic materials. The object of the study is a concrete canvas. The analysis included methods of empirical and experimental-theoretical level. The work considered and compared such cladding materials as geomembrane, bentonite mats and concrete cladding as a traditional cladding material. The given theoretical provisions of the work allow for the possibility of applying small mechanized equipment when carrying out works on cleaning the canal beds covered with concrete canvas from sediments.

Axial compressive responses of concrete canvas and CFRP reinforced corroded concrete short columns

To evaluate the axial compression performance of corroded concrete short columns reinforced by concrete canvas (CC) and carbon fiber reinforced polymer (CFRP), a total of 16 specimen sets with different reinforcement forms and corrosion rates are designed and examined in this paper. Specimens are subjected to electrochemically-induced corrosion before being mechanically tested under the compressive load. The assessed variables are theoretical corrosion rate (0, 5%, or 10%), number of CFRP wrapping layers (0, 1, 2, or 3), and number of CC layers (0 or 1). Through the signal localization of acoustic emission (AE) and the variation in characteristic parameters, it is found that the presence of CC changes the failure morphology of the specimen and improves the uneven deformation of concrete in the core area. Also, under the same number of CFRP wrapping layers, the peak stress of the CC and CFRP jointly reinforced specimens is reduced by about 10% but has a more than 70% increase in the ultimate strain compared with those of CFRP reinforced only, which proves that the jointly reinforced method exhibits high plasticity deformation ability. With an increase in corrosion rate, compared with the uncorroded specimens, the peak stress of JC specimens decreases by more than 6.9% but the ultimate strain increases by more than 15.4%. The JC specimens’ peak stress and ultimate strain models are then determined through fitting, from which a good correlation with those observed is witnessed. The comparison shows that the model has good accuracy and can provide a theoretical basis for further research for CC- and CFRP-reinforced corroded concrete short columns.