Top PDF Behaviour of circular concrete columns reinforced with GFRP bars and GFRP helices

Behaviour of circular concrete columns reinforced with GFRP bars and GFRP helices

Behaviour of circular concrete columns reinforced with GFRP bars and GFRP helices

Fibre reinforced polymer (FRP) composite materials in the constructing of new structures and retrofitting of the existing structures is a novel invention that can replace the conventional steel bars and plates because FRP materials can eliminate the corrosion problem. Corrosion is a considerable issue in the humid, aggressive, and coastal areas that causes large maintenance cost and sometimes the structure loses its performance 1 . In general, FRP composite is produced in Glass (G), Carbon (C) and Aramid (A) fibre, while the glass fibre is most familiar to produce FRP bars because glass fibre is cheaper than carbon fibre and its characteristics is better than aramid fibre. However, the mechanical properties of GFRP bars are different than steel bars because GFRP bars have higher tensile strength to weight ratio and their modulus of elasticity is about a quarter of the steel bars. The behaviour of GFRP bars under compression is complex because some different parameters such as debonding or buckling of the fibres can play roles. Therefore, to figure out the behaviour and the effect of GFRP bars on the Reinforced Concrete (RC) columns and the lack of experimental studies in this field, 18 circular concrete columns were cast and reinforced with conventional steel and GFRP bars and helices. Four of the specimens were confined externally with CFRP sheets. The specimens were tested under concentric, eccentric and flexural loading in this study.
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Structural Behaviour of Circular High Strength Concrete (HSC) Columns Reinforced with Glass Fibre-Reinforced Polymer (GFRP) Bars and Helices under Different Loading Conditions

Structural Behaviour of Circular High Strength Concrete (HSC) Columns Reinforced with Glass Fibre-Reinforced Polymer (GFRP) Bars and Helices under Different Loading Conditions

Four specimens (the first specimen in each group) were tested under concentric axial load. Fig. 5.9 presents the axial load-axial deformation behaviour of the concentrically loaded specimens (S60E0, G60E0, G60E0F and G30E0F). The ascending part of the axial load-axial deformation curves of Specimens S60E0, G60E0, G60E0F and G30E0F experienced similar patterns up to the first peak load ๐‘ƒ ๐‘ƒ๐‘’๐‘Ž๐‘˜ 1 and was mainly governed by the compressive strength of the concrete. This is because the lateral confinement provided by the transverse reinforcement (steel or GFRP helices) had little or no effect up to the first peak load due to the relatively low lateral dilation of the concrete. Similar observations were reported in Cusson and Paultre (1994) [10] and in Paultre et al. (2010) [29] for the steel bar reinforced HSC and SFHSC columns, respectively, and in Afifi et al. (2015) [15] for the GFRP bar reinforced concrete columns. The concrete cover of the concentrically loaded specimens did not crack until the specimens reached about 95% of the first peak load, where hairline cracks began to appear. With further loading, the hairline cracks widened and developed into vertical cracks. The maximum axial load sustained by the reference Specimen S60E0 was 2735 kN, which was about 0.5% higher than the maximum axial load of Specimen G60E0. Although the direct replacement of the steel reinforcement with the same amount of GFRP reinforcement resulted in a reduction in the maximum axial load carrying capacity of the columns [17, 30], Specimen G60E0F sustained about 2% higher axial load than the reference Specimen S60E0. The higher axial load sustained by Specimen G60E0F was attributed to the presence of the steel fibre which led to an increase in the compressive strength of the concrete by restraining the formation of the cracks and thereby increasing the axial load of the specimen. Specimen G30E0F sustained about 9% higher first peak load (๐‘ƒ ๐‘ƒ๐‘’๐‘Ž๐‘˜ 1 ) than the reference Specimen S60E0.
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Behaviour of concentrically loaded geopolymer-concrete circular columns reinforced longitudinally and transversely with GFRP bars

Behaviour of concentrically loaded geopolymer-concrete circular columns reinforced longitudinally and transversely with GFRP bars

and C.E. values of the tested columns. Based on the experimental results, the ductility index and confinement efficiency increased when the amount of transverse reinforcement increased. These results are consistent with Afifi et al.โ€™s [39] findings on circular concrete columns reinforced with GFRP bars and spirals. Sharma et al. [58] also reported a similar trend regarding the ductility of the confined columns for conventional RC columns. The geopolymer concrete columns with spiral reinforcement, in general, showed higher ductility and confinement efficiency than those with circular hoops. These findings are not consistent with those of Mohamed et al. [40] wherein they concluded that the FRP circular hoops have similar confining efficiency as the FRP spirals. This could be expected since they utilized hoops with longer lap or splice lengths, approximately 2.5 to 5 times longer than that of the hoops employed in this study. The ductility and confinement efficiency of the slender geopolymer concrete columns were not considered in this study, mainly because of the nature of failure of these specimens.
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Experimental investigation of the behaviour of concrete beams reinforced with GFRP bars under static and impact loading

Experimental investigation of the behaviour of concrete beams reinforced with GFRP bars under static and impact loading

FRP has been used extensively for strengthening structural components including the application of FRP sheets or plates as external reinforcement to the exterior surface of beams [1] and slabs [2]. Also, FRP sheets have been used to repair damaged reinforced concrete (RC) columns [3]. The use of FRP as external reinforcement not only provides additional strength but also provides confinement to a deteriorated structure. FRP bars have also been used as internal reinforcement in reinforced concrete beams [4] and slabs [5]. The use of FRP bars in civil infrastructures is advantageous especially for structures located in marine and salt environments. As FRP is a non-corrosive material, they are resistant to corrosion due to the exposure to de-icing salts. It is noted that, for conventional steel RC structures, exposure to harsh environments including moisture and temperature reduces the alkalinity of the concrete and causes corrosion of the steel reinforcement and ultimately results in the loss of serviceability and strength. Internal FRP reinforcement is also beneficial in increasing the load carrying capacity of beams, especially for beams constructed with high strength concrete [6]. Also, increasing the FRP tensile reinforcement ratio is a key factor in enhancing load carrying capacity and controlling deflection [7].
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Evaluation of the flexural strength and serviceability of geopolymer concrete beams reinforced with glass-fibre-reinforced polymer (GFRP) bars

Evaluation of the flexural strength and serviceability of geopolymer concrete beams reinforced with glass-fibre-reinforced polymer (GFRP) bars

Reinforced concrete (RC) is one of the most commonly used composite materials in the construction of roads, bridges, buildings, and other civil infrastructures. The demand for this material is expected to increase in the future owing to the rise of infrastructure needs in many developing and industrialised countries. In fact, it is estimated that the total global infrastructure demand amounts to USD 4.0 trillion with a gap of at least USD 1.0 trillion per year [1]. Due to the serviceability and economic issues owing to the costly repair and rehabilitation of damaged RC structures caused by the corrosion of the steel bars and the sustainability issue owing to the extremely resource- and energy-intensive process of producing steel and cement materials, however, many engineers and researchers have sought viable alternatives. Among the solutions that are currently being employed are replacing cement- based concrete with geopolymer concrete and replacing steel bars with fibre-reinforced polymer (FRP) bars. Neither, however, can solve the issues altogether.
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Three-dimensional nonlinear finite element analysis of concrete deep beam reinforced with GFRP bars

Three-dimensional nonlinear finite element analysis of concrete deep beam reinforced with GFRP bars

The shear capacity of deep beams is a major issue in their design. The behavior of reinforced concrete deep beams is dif- ferent from that of slender beams because of their relatively larger magnitude of shearing and normal stresses. Unlike slen- der beams, deep beams transfer shear forces to supports through compressive stresses rather than shear stresses. There are two kinds of cracks that typically develop in deep beams: ๏ฌ‚exural cracks and diagonal cracks. Diagonal cracks eliminate the inclined principal tensile stresses required for beam action and lead to a redistribution of internal stresses so that the beam acts as a tied arch. The arch action is a func- tion of a/d (shear span/depth) and the concrete compressive strength, in addition to the properties of the longitudinal reinforcement. It is expected that the arch action in FRP rein- forced concrete would be as signi๏ฌcant as that in steel rein- forced concrete and that the shear strength of FRP- reinforced concrete beams having a/d less than 2.5 would be higher than that of beams having a/d of more than 2.5 [2]. The application of the reinforced concrete deep beams within structural engineering practice has risen substantially over the last few decades. More specially, there has been an increased practice of including deep beams in the design of tall buildings, offshore structures, wall tanks and foundations. They differ from shallow beams in that they have a relatively larger depth compared to the span length. As a result the strain distribution across the depth is non-linear and cannot be described in terms of uni-axial stress strain characteristics [3]. Prediction of behavior of deep beams by design codes which contain empirical equations derived from experimental tests has some limitations. They are only suitable for the tests con- ditions they were derived from, and most importantly, they fail to provide information on serviceability requirements such as structural deformations and cracking. Likewise, the strut and tie model, although based on equilibrium solutions thus pro- viding a safe design, does not take into account the non-linear material behavior and hence also fails to provide information on serviceability requirements. Cracking of concrete and yielding of steel are essential features of the behavior of
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A Systemically Reconsideration of Torsional behaviour of Rectangular Reinforced Concrete Beams Bound with GFRP

A Systemically Reconsideration of Torsional behaviour of Rectangular Reinforced Concrete Beams Bound with GFRP

ABSTRACT: Environmental degradation, improved service loads, reduced capability because of the aging, degradation owing to terrible construction materials and workmanships and the basic need for rehabilitation and repair of existing structures have been demanded by conditional need for seismic retrofitting. Fibre reinforced polymers has been utilized effectively in a lot of such uses for factors like lower weight, higher power and durability. In the experimental action up, performance and behaviour of concrete beams rectangular in shape is actually strengthened with externally bonded GFRP (glass fiber reinforced polymer) for research of torsion. Investigate was carried out on rectangular RC beams bonded with GFRP. This set was under test to determine to detect result of transferring transfer torque to main part of the beam utilizing cantilever situated at reverse arms. Every arm in the set up was situated under a few static load. This was damaging sort of testing need and all beams are actually meant to get produce fail results so far as torsion in considered. Out of 8 beams under test one beam is actually call as management beam and any other beams are actually strengthened using various kinds of configuration to confirm the impact of various configuration. KEYWORDS: Concrete Beams, Wrapping, GFRP, reinforced concrete, T- beam, torsional strength
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Flexural analysis of concrete beams longitudinally reinforced with GFRP bars using discrete element model

Flexural analysis of concrete beams longitudinally reinforced with GFRP bars using discrete element model

Finch, E., et al. (2003) developed a discrete element model to observe the difference between weak and strong sedimentary covers deformation in response to basement thrust faulting. The model was used to study the influence of the dip of the basement fault and the strength of the sedimentary overburden on the geometry of the folds generated by block movements in the basement and the rate of fault propagation. The discrete element model used circular particles connected by breakable elastic springs. Particles are bounded until the separation between them reaches a defined breaking strain and the bond breaks. The discrete element model proved to be great help in studying tectonic processes and related geological structures as it has the ability to record the developments of structures with large deformation.
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Shear strength analysis of concrete beams reinforced with GFRP bars using strut and tie model

Shear strength analysis of concrete beams reinforced with GFRP bars using strut and tie model

Through a collaboration project between the University of Sherbrooke, the Ministry of Transportation of Quebec (MTQ), and an FRP manufacturer, new FRP (carbon and glass) stirrups have been recently developed and characterized according to B.5 and B.12 test methods of ACI 440.3R-04 (ACI Committee 440., 2004). The behavior of these stirrups in large-scale beam specimens, however, had not been investigated. To achieve this, an experimental program was conducted to investigate the shear performance of FRP stirrups in large-scale beam specimens. The first phase evaluated the structural performance of carbon FRP (CFRP) stirrups in beam specimens. There is a recent increase in demand for glass FRP (GFRP) bars because of its many successful applications, including bridge deck slabs,(Benmokrane et al., 2006,2007) barrier walls, (El-Salakawy et al., 2003; El-Gamal et al.,2008) parking garages (Benmokrane et al.,2006), continuous pavement (Benmokrane et al.,2008), and other concrete structures. Furthermore, considering the lower costs of GFRP bars in comparison to CFRP and aramid FRP (AFRP), GFRP reinforcement is becoming more attractive for the construction industry.
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Mechanical Charecterization Of Glass Fiber Reinforced Polymer (GFRP) Bars.

Mechanical Charecterization Of Glass Fiber Reinforced Polymer (GFRP) Bars.

ride-free environment. When reinforcing bars undergo oxida- tion due to chloride attack, oxidation products of steel with considerably larger volume are produced. This oxidation prod- uct volume increase in turn generates additional radial tensile stresses around the bar, in matrix. With the advent of fiber reinforced polymers (FRP) consisting of high-strength fibers in a polymer matrix, an alternative has been found for reinforcing concrete structures to address corrosion problems. The fibers in FRP composites are the main load-carrying elements. The polymer matrix (cured resin) protects the fibers from damage, ensures good alignment of fibers, and allows load distribution among individual fibers. Fibers are selected based on the strength, stiffness, and durability requirement for specific ap- plications. Resins are selected based on the function and manufacture of the FRP bar. Fiber types that are typically used in the construction industry are carbon and glass, with thermo- set epoxy, vinyl ester, polyester, and urethane resins, even though aramid has been used occasionally.
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STUDY OF TORSIONAL BEHAVIOUR OF RECTANGULAR REINFORCED CONCRETE BEAMS WRAPPED WITH GFRP

STUDY OF TORSIONAL BEHAVIOUR OF RECTANGULAR REINFORCED CONCRETE BEAMS WRAPPED WITH GFRP

The present experimental study is made on the torsional behavior of rectangular RC beams strengthened by uni-directional and bi-directional GFRP fabrics. Nine rectangular RC beams having same reinforcement detailing and designed to fail in torsion and are cast and tested till collapse. During testing deflections and strain measurements are observed with the help of dial gauges and strain gauge. Following conclusions are drawn from the test results and calculated strength values:

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Ductile Failure of Concrete Beam Reinforced with GFRP

Ductile Failure of Concrete Beam Reinforced with GFRP

61 Significant research has been devoted to beams and columns retrofitted with FRP and numerous models were proposed. Some of it in the strengthening of steel structures, where carbon FRP is preferred to glass FRP due to its much higher elastic modulus and strength. The critical difference between FRP-to-concrete and FRP-to- steel bonded interfaces is that the concrete is usually the weak link in the former, while in the latter the adhesive is the weak link. Failure at the steel/adhesive and FRP/adhesive interfaces can be avoided by careful selection of the adhesive and appropriate surface preparation of the steel and FRP [10]. Avoiding adhesive failure has been addressed in a separate study [11]. Different test methods for bonded joints have been used by different researchers [12]. The bond performance of sand- coated glass fiber-reinforced polymer (GFRP) bars into geopolymer concrete with a compressive strength of 33 MPa was investigated under a direct pullout test. The effects of parameters such as bar diameter (12.7, 15.9, and 19.0 mm) and embedment length (5, 10, and 15 d b , where d b is the bar diameter) were evaluated. The results showed that the maximum average bond stress obtained is around 23 MPa. As GFRP bar diameter increases, the average bond stress decreases. The specimens with shorter embedment length failed because of pullout of the bars, whereas those with longer embedment lengths failed because the concrete split. The results further revealed that the geopolymer concrete reinforced with GFRP bars have a bond strength similar to that of steel-reinforced geopolymer concrete. Finally, bond-slip models for the ascending branch up to maximum bond stress of the bond-slip curves for GFRP bars and geopolymer concrete were proposed. [13]. New approach that incorporates the effects of temperature, design life, and relative humidity (RH) of exposure into the environmental reduction factor (RF) for glass fiber reinforced polymer (GFRP) bars used as concrete re-inforcement. By using time extrapolation and time-temperature shift approaches, a new equation for design strength of GFRP bar under various exposure time and temperature was proposed [14]. Eight beams, including two control beams reinforced with only steel or only GFRP bars, were tested. The amount of reinforcement and the ratio of GFRP to steel were the main parameters investigated experimentally and theoretically. Hybrid GFRP/steel-reinforced concrete beams with normal effective reinforcement ratios exhibited good ductility, serviceability, and load carrying capacity.
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Ductility Behaviour of Steel Fibre Reinforced Concrete Beam Strengthened with GFRP Laminates

Ductility Behaviour of Steel Fibre Reinforced Concrete Beam Strengthened with GFRP Laminates

The use of concrete structures reinforced/ pre-stressed with fibre-reinforced polymer (FRP) composite materials has been growing to overcome the common problems caused by corrosion of steel reinforcement. FRP composites are lightweight exhibit high tensile strength and specific stiffness, are easily constructed. Due to these advantageous characteristics, FRP composites have been included in new construction and rehabilitation of structures through its use as reinforcement in concrete, bridge decks, modular structures, formwork, and external reinforcement for strengthening and seismic upgrade. Extensive research programs have been conducted to investigate the flexural behaviour of concrete members reinforced with FRP reinforcement. The structural elements can be strengthened by varieties of Fibre Reinforced Polymer (FRP) such as Carbon fibre reinforced polymer (CFRP), Glass fibre reinforced polymer (GFRP), Steel fibre reinforced polymer (SFRP) or Wooden fibre reinforced polymer (WFRP).
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Flexural response of GFRP-reinforced geopolymer concrete beams

Flexural response of GFRP-reinforced geopolymer concrete beams

Many studies have shown that geopolymer concrete has physical and mechanical properties that are suitable for structural applications (4-6). In fact, the geopolymer concrete internally reinforced with steel bars has been successfully utilised in the construction of several civil infrastructures such as pavement, retaining walls, and bridges. However, in order to maximize its full potential for various structural applications especially in harsh environment, the corrosion of steel reinforcements must be avoided or must be eliminated, if possible, since this phenomenon results in geopolymer concrete cracking and spalling that can lead to early strength degradation and loss of serviceability of the structure before reaching its expected service life. Among the possible solutions that are being implemented to address this concern is to utilise fibre reinforced polymer (FRP) bars because, aside from being corrosion- resistant, these bars have high tensile strength, lightweight, high fatigue endurance, electromagnetic neutrality, and have low thermal and electrical conductivity (7).
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Experimental study on diagonal shear cracks of concrete beams without stirrups longitudinally reinforced with gfrp bars

Experimental study on diagonal shear cracks of concrete beams without stirrups longitudinally reinforced with gfrp bars

An experimental study on diagonal shear cracks of concrete beams without stirrups was carried out. A total of twenty four reinforced concrete beams, consisted of twelve beams reinforced with GFRP bars and twelve beams reinforced with conventional steel bars, were tested up to failure. Test variables in this study were: (1) concrete compressive strength; (2) longitudinal reinforcement ratio; and (3) shear span-effective depth ratio. Beam capacities, slope of the diagonal shear cracks, strains at the maximum concrete compression fiber and selected position of longitudinal reinforcement were observed during the test. The diagonal shear cracking loads obtained from the test were compared to that calculated using empirical equations available in ACI code and Eurocode 2. The test results showed that shear strength of beams reinforced with GFRP bars was lower than that of the beams with conventional steel bars. It was found that the ratio of longitudinal reinforcement significantly influences the failure type and crack pattern in the shear span zone. In addition, the tensile strain of longitudinal reinforcement at the support considerably increases after the occurrence of diagonal cracks.
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Flexural performance of concrete slabs reinforced with GFRP rebars

Flexural performance of concrete slabs reinforced with GFRP rebars

Figure 2 shows the mechanical loading test set-up. In this test, the slab specimens were simply supported with a span of 2400 mm and a shear span of 800 mm. All concrete specimens were subjected to two concentrated loads, each applied at one third of the 2400 mm tested length. Strain gauges, 5 mm long type BFLA-5-3 [ 6 ], were bonded longitudinally onto the rebars of each test specimen. They were positioned halfway between two spiral wraps. Each rebar had one 5 mm strain gauge placed at midpoint of the GFRP rebar. The idea of using strain gauges was to monitor the movements of the GFRP rebars under applied loads.
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Exterior Concrete Beam-column Connection Reinforced with Glass Fiber Reinforced Polymers (GFRP) bars under Cyclic Loading

Exterior Concrete Beam-column Connection Reinforced with Glass Fiber Reinforced Polymers (GFRP) bars under Cyclic Loading

By connecting the maximum story drift points corresponding to each displacement level, the load-story drift envelope curve is obtained. In Figure 14a and b, the load-story drift envelope curve of the specimens reinforced with steel and FRF are illustrated. ACI Committee [33] suggested provisions for a connection to be accepted as an element of a moment resistant frame in seismic regions. Based on this code, in the third cycle in which the drift of 3.5% is obtained, the maximum applied load in each loading direction should not be less than 75% of the maximum lateral strength in the aforesaid direction to satisfy the fracture criterion. Moreover, the observed energy ratio should not be less than 0.125, and the secant stiffness about zero (the secant stiffness corresponding to the drifts ranged from -0.35% to 0.35%) should not be less than 5% of the initial stiffness at the first cycle of the aforesaid direction. Based on Figures 14a and b and the requirements of ACI Committee [33], the seismic behavior of the specimens were assessed. Accordingly, the behavior of the specimens reinforced with the steel bars is acceptable. Moreover, the specimens reinforced with the FRP bars satisfied the acceptance criteria of ACI Committee [33], and the behavior of the specimen 7 and 8 with high strength concrete were acceptable as well. Note that; the specimens 5 and 6 did not satisfy the criteria of the 3.5% drift. Hence, they could not be accepted. According to Corleyโ€™s suggestions [25], the performance of specimens 5 and 6 was not satisfactory. Corley [25] suggested the third cycle in which the drift of 3% was occurred for satisfying the fracture criterion. In this displacement, the connection behavior ought to be stable. Specimens 5 and 6 were not able to reach the drift of 3% although the behavior of specimen 5 was stable in drifts beyond 3% due to the compressive forces. Based on the load-story drift envelope curves, usage of GFRP bars in connection showed an acceptable drift capacity, assuming a minimum drift demand of 3% as suggested in the literature for ductile frame structures [25].
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Behavior of High Strength Concrete (HSC) Reinforced Beam with GFRP Bars Using Plastic Damaged Concre
                ย 

Behavior of High Strength Concrete (HSC) Reinforced Beam with GFRP Bars Using Plastic Damaged Concre ย 

Abstract โ€” Reinforced concrete structures consists of two main components and the behavior of these structures influenced by gender and material properties, in order to investigate the behavior of concrete reinforced beam that most important flexural element in reinforced concrete structures, we chosen High Strength Concrete (HSC) for concrete and GFRP and steel bars for reinforcement. For compare the new beam element(high strength concrete and GFRP bars) ,with general beam (general concrete and steel bars) finite element software ABAQUS used, therefore flexural beam models in this software after simulation and analysis, the results shows that the stress in this elements are reduced.
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Shear behaviour of macro-synthetic fibre-reinforced concrete beams GFRP reinforcement

Shear behaviour of macro-synthetic fibre-reinforced concrete beams GFRP reinforcement

The test results revealed that the inclusion of different volumes of macro synthetic fibre enhanced the shear failure behaviour of GFRP reinforced concrete beams, and [r]

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Study on Reinforced Concrete Beam Strengthened with GFRP and PCM

Study on Reinforced Concrete Beam Strengthened with GFRP and PCM

Concrete is the most widely-used construction material in the world of civil infrastructure over several decades. Reinforced-concrete (RC) structures are subjected to deterioration during their service life. Thus rehabilitation works are often required to restore the performance of these deteriorated structures. There are several materials that have been introduced in the construction industry for repairs of deteriorated structures. Among them, the most commonly used materials are polymer cement mortar (PCM), fiber-reinforced polymer (FRP) and ultra-high- strength fiber-reinforced concrete (UFC) panels. Fibre- reinforced plastic (FRP) is a composite material made of a polymer matrix reinforced with fibres. The use of FRP composite materials with various types of fibre reinforcements has become an alternative for reinforcement in various concrete members. Carbon Fibre Reinforced Polymer (CFRP) is the best type of FRP strengthening. But because of its high cost, its use is being limited. Thus, this makes Glass Fibre Reinforced Polymer (GFRP), the most commonly used type of FRP strengthening technique. Polymer Cement Mortar (PCM) is a cementitious material having better adhesive strength and resistance to aggressive environments compared to ordinary mortar and concrete.
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