Papers by Keyword: Concrete Reinforcement

Abstract: When discussing graphene materials, their mechanical strength, impermeability, flexibility, thermal and electrical conductivity, and lightness are key reference points, earning them the moniker "all-in-one material. “This versatility makes graphene suitable for various applications, including electronics, medicine, plastics, coatings, construction, and renewable energies. However, it's crucial to note that the behavior of these materials at the nanometric scale depends on factors such as the type of graphene, functionalization, concentration, and the specific processes involved in each industry. Since the isolation of graphene in 2004, significant efforts have been made to comprehend its multifunctional properties. Nevertheless, the primary challenge lies in translating this knowledge from the laboratory to industrial applications, hampered by the high cost and low yield of graphene. Fortunately, the construction industry, particularly the concrete and coatings sector, appears to be one of the most promising fields for the integration of this nanotechnology. In this context, we present a diverse array of representative trials conducted on various concrete designs and environmentally friendly, antimicrobial, and anticorrosive coatings enhanced with graphene materials. These trials showcase the multifunctional enhancement of properties thanks to the incorporation of graphene materials in different commercially available products tailored for industrial applications, demonstrating that graphene not only represents a technological innovation but is also a catalyst for more sustainable practices in various industries. Its ability to improve the efficiency of different products and applications, becomes graphene as a key material in the immediate future with which industries operate within ecological limits while meeting human needs.

Abstract: The research builds upon the analysis of bent glass-fibre-reinforced-polymer reinforcement. The presented work focuses on examining the influence of anchor length on the overall tensile strength of bent FRP rebar. In general, to ensure secure anchoring of the reinforcement in concrete, it is necessary to determine a specific length of the straight section of the rebar beyond the bend, which prevents the reinforcement from being pulled out of the concrete. A total of 27 pieces of bent rebar were tested in the research and divided into four subgroups based on the anchor length beyond the bend. The reference value of the load-carrying capacity of the straight reinforcement was tested on four experimental samples. The research results confirmed that the reduction in tensile strength depends on the anchor length and suggest that the minimum anchorage length stated in the literature should be sufficient; exceeding it does not lead to a significant increase in the load-carrying capacity of the rebar. The research findings expand the Czech Republic’s design knowledge of FRP reinforcement and facilitate the resolution of subsequent phases of the project.

Abstract: This research aims to analyze the mechanical behavior of concrete reinforced with polyolefin fibers. The intention is to evaluate the possibility of using concrete as a structural material without steel bars in its interior. For this purpose, specimens with different dosages of polyolefin fibers were prepared, and bending and compression tests were carried out. The results show no significant increase in mechanical strengths, especially in bending, but it is interesting in the mechanical behavior after the first cracking. Controlling cracking is considered beneficial for sustainability.

Abstract: The construction concrete printing requires new approaches at reinforcement performing. Only successful integration of the existing reinforcement systems will provide for the opportunity to design concrete structures and make objects with the help of additive technologies. The paper dwells upon the issues of possibilities and the efficiency of disperse reinforcement with basalt fibers. It presents a composition of a composite material for 3D printing of a type of fine-grained fibrous concretes with the required technological properties: a necessary plasticity and a high plastic strength for printing large-dimensioned items and structures without timbering by means of extrusion with a high material adhesion between the layers and controlled setting periods. The author studied a possibility to reclaim basalt fiber production wastes as a high-disperse fibrous filler for the reinforcement of polymer-modified concretes. The article provides the dependence of plastic strength on the fiber content in concrete. The authors consider the influence of components and the mechanism of modifying disperse particles of basalt fibrous concrete at obtaining the material for 3D printing. The obtained polymer-modified basal fibrous concrete has a good impact resistance, low water absorption and high crack resistance.

Abstract: This paper will systematically study the different shapes of steels corrosion rate under different corrosion environments through accelerated corrosion test of orthogonal experiment and the corresponding physical tests and electrochemical detection methods. The experimental results show that the corrosion resistance of the deformed bar is poorer than the plain round bar. In the same corrosive environment, its tensile strength, yield strength and elongation decline are more significantly than the round steel, and the change of the elongation is more obvious. Experimental results also show that in the environment which is absence of chloride ion, reinforced is basically with uniform corrosion in previous time, late stage for the development of local corrosion, the mechanics performance index is also present a corresponding positive correlation with the corrosion situation. But the uneven corrosion condition appears at the previous period when it is in the chlorine ion environment. In this condition, the mechanical performance and corrosion situation is no longer in linear relationship, but the trend of rapidly decline. Results of weightlessness rate test confirm that the correlation of degree of corrosion and the mechanical properties.

Abstract: In order to achieve internal reinforcement of concrete bridges quantitative nondestructive testing, this paper has adopted linear polarization method to test reinforcement passivation in the pore solution of simulated concrete and corrosion current density value in the corrosion process under different external environments and has built calculation model for amount of reinforcement corrosion based on detection signal. That is to say a new idea, which makes the evaluation results more effective, has been put forward to efficiently correspond with reinforcement corrosion ratio with potential signal, and the quantification evaluation for damage of reinforced concrete can be carried directly. It has modified theoretical model and analyzed the error through weightlessness tests. The research result shows that the calculation model after modified can significantly improve the detection accuracy for the actual rate of reinforcement corrosion. CLC: TU528.33 Document code:

Abstract: The carbon fiber is applied to the bridge reinforcement as the intelligent material because of the electrocaloric effect, which can improve the bearing capacity and the deformation capacity of the bridge. This paper investigated the application of the carbon fiber concrete in the maintenance of Guan Yin Dang bridge. With the combination of the analytical and experimental methods, we can obtain the calibration coefficient for the structure. The maximum calibration coefficient of the stress at the mid-span is less than 1, and meets the requirement of the criterion. The results demonstrate that applying the carbon fiber concrete in the bridge reinforcement is an effective method, which may provide a basis for the bridge intelligence of reinforcement and health inspection.

Abstract: This paper presents a new non-destructive testing (NDT) for reinforced concrete structures, in order to identify the components of their reinforcement. A time varying electromagnetic field is generated close to the structure by electromagnetic devices specially designed for this purpose. The presence of ferromagnetic materials (the steel bars of the reinforcement) immersed in the concrete disturbs the magnetic field at the surface of the structure. These field alterations are detected by sensors coils placed on the concrete surface. Variations in position and cross section (the size) of steel bars immersed in concrete originate slightly different values for the induced voltages at the coils.. The values ​​for the induced voltages were obtained in laboratory tests, and multi-layer perceptron artificial neural networks with Levemberg-Marquardt training algorithm were used to identify the location and size of the bar. Preliminary results can be considered very good.

Abstract: Thermomechanical controlled processing of concrete reinforcement bars, comprising quenching and autotempering, produces a microstructural gradient across the diameter - tempered martensite near to the surface, bainite and/or degenerated pearlite in the intermediate layers and pearlite-ferrite within the core. Since martensite is the strength controlling phase in steels, its fractional thickness in TMCP bars have beeen correlated to tensile properties. The developed empirical model, helped in revealing that upto a fractional rim of about 20%, volume fraction of ferrite-pearlite predominantly influenced the YS, UTS and % elongation, whereas at higher fractions, martensite found to control these properties.

Abstract: This paper describes the work that is being done at the University of Minho concerning the development of braided rods for concrete reinforcement. A preliminary research study has been conducted to understand the mechanical behaviour of braided fabrics. Various samples have been produced varying the type of fiber (glass, polyester and aramid), the type of braided fabric (simple, hybrid and core reinforced) and in the latter case, the number of core reinforcing yarns. The tensile properties of these samples have been evaluated and the results presented. The influence of each factor on the tensile properties of braided fabrics has also been analysed and discussed. In order to produce braided reinforced composite rods to use as a concrete reinforcement, a special technique has been developed using a standard vertical braiding machine. The braided reinforced composite materials have been produced in rib structure to improve adhesion between them and the concrete. Special samples have been prepared and tested to evaluate the adherence between both materials involved. The tensile and bending properties of braided reinforced composite rods have been evaluated and the results obtained presented and discussed.