Sage Journals: Discover world-class research

Abstract

To study the reinforcement effect of textile-reinforced concrete (TRC) on concrete structures in a marine environment, a four-point bending loading method was used for graded loading to analyze the influence of the dry–wet cycle number, the reinforcement method, and chopped fiber addition on the flexural properties of load-holding reinforced concrete beams reinforced with textile-reinforced concrete. The results show that with the increase of dry–wet cycle numbers, the crack width and deflection of beams develop faster and the bearing capacity decreases. The performance of the prefabricated textile-reinforced concrete plate is close to that of a cast-in-place textile-reinforced concrete in limiting crack, bearing capacity, and deflection deformation. The addition of chopped fibers in fine-grained concrete can improve the reinforcement effect of textile-reinforced concrete. Based on the experimental results and referring to the relevant design codes and literature, the calculation formula of the bearing capacity of TRC-strengthened beam with a secondary load is established, and the calculated values are in good agreement with the actual values.

Keywords

Textile-reinforced concrete beam with a secondary load bending performance chloride environment dry–wet cycle

Introduction

Damage of concrete structures caused by insufficient durability is very common, especially the durability problem of marine concrete structures, which shows a yearly increasing trend. Most of these concrete structures are in a chloride corrosion environment, and with the increase of service time, the mechanical and overall properties deteriorate, damaging, or even destroying, the structures.¹ Therefore, the reinforcement and repair of concrete structures are necessary.

Fiber-reinforced polymer (FRP) is a typically used reinforcement material. Deng et al.² used infrared detection technology to record the interfacial fatigue behaviors between FRP and concrete, and the result showed good interfacial anti-fatigue properties of FRP. Chotickai and Somana³ showed that a chlorine salt dry–wet cycle environment had no significant effect on the bond strength of carbon fiber–reinforced polymer (CFRP) composite materials and the tensile side of the concrete beam. Zhu et al.⁴ carried out an experimental study on the bending capacity of reinforced concrete (RC) beams strengthened with CFRP considering secondary load, and the result showed that the flexural capacity of beams, strengthened with CFRP after damage, can also be improved significantly.

FRP can have a better reinforcement effect, but there are also some limitations, such as poor high-temperature resistance and fire resistance and difficulty working on wet concrete surfaces. The emergence of cement-based reinforcement materials can solve these problems better.⁵ Textile-reinforced concrete is a new type of cement-based composite material, which has good coordination with old concrete, and it can hardly change the original component section size when used to reinforce a structure.⁶ These characteristics provide TRC with a broad application prospect in the repair and reinforcement of marine concrete structures.

At present, scholars further research TRC-strengthened flexural members. The study of Larbi et al.⁷ showed that TRC could improve the bearing capacity and crack-limiting ability of beams to a certain extent, but could not provide significant gain in terms of ductility. Contamine and Larbi⁸ developed a kind of TRC material suitable for repairing reinforced concrete beams by in situ contact molding, and the composite is made of a polymer-modified cementitious matrix reinforced with grids of alkali-resistant (AR) glass yarns. The results from Verbruggen et al.⁹ showed that the TRC reinforcement layer had good crack bridging ability and its application on the full width of a beam was beneficial to bearing capacity improvement and crack width limitation. The experimental results of Truong et al.¹⁰ showed that the reinforcement effect of TRC was good and that it would not be affected by the precracking of the beam. Xu et al.¹¹ studied the mechanical properties of TRC-strengthened beams with a secondary load under conventional conditions. The experimental results showed that the increased amplitude of the ultimate load of the reinforced beams decreased with the damage degree increase and that the TRC thin plate could better limit crack development, showing good toughness. Furthermore, the research of Gopinath et al.¹² showed that TRC was an effective method for reinforcing the tensile zone of beams under chloride erosion. The results of Yin et al.¹³ and Sheng et al.¹⁴ showed that the bonding performance between TRC and old concrete would be affected by the coupling effect of load and the dry–wet cycle with chloride; furthermore, TRC still played a better role in improving the crack development and fatigue life of beams.

However, the actual structure is generally sustaining a load when reinforced, and research on TRC-strengthened beams with a secondary load under an erosion environment is less at present, and so further study is needed. On the basis of summarizing the previous research and combining with engineering practice, this article studies a TRC-strengthened beam with a secondary load under a marine environment and considers the influence of the dry–wet cycle number, reinforcement method, and chopped fiber addition on the flexural properties of load-holding RC beams reinforced with TRC.

General experimental situation

Specimen design

A total of six beams, H1–H6, were made in the experiment. The size of the unreinforced beam was 100 mm × 190 mm × 1200 mm, the size of the reinforced beam was 100 mm × 200 mm × 1200 mm (the thickness of two textile layers was 10 mm), and the thickness of the protective layer was 20 mm. The detailed reinforcement is shown in Figure 1, and the detailed information of the beam is shown in Table 1.

Figure 1.

Size, reinforcement, and measurement equipment layout.

Table 1.

Information on the specimens.

Number	Dry–wet cycles	Reinforcement method	Chopped fiber
H1	240	Casting	–
H2	270	Casting	–
H3	300	Casting	–
H4	270	Prefabrication	–
H5	270	Casting	AR glass
H6	270	Casting	PVA

PVA: polyvinyl alcohol; AR: alkali resistant.

Concrete

In the experiment, C40 concrete was used. The mix proportion is cement:water:medium sand:gravel:water reducer = 415:161:643:1181:2.85, respectively. The average strength measured after curing the concrete cube standard test block of 150 mm × 150 mm × 150 mm for 28 days was 45.29 MPa.

Steel bar

Two main reinforcements were arranged in the tensile area; the grade was HRB400, the diameter was 12 mm, and the yield strength measured by tensile test was 518 MPa. Erection bars were two steel bars with a diameter of 12 mm and grade of HPB300, and the stirrups were steel bars with a diameter of 6.5 mm and grade of HPB300. The stirrup spacing of shear bending section was 60 mm and that of the pure bending section was 150 mm, as shown in Figure 1.

Textile

The experiment used the textile adopted in the literature;⁶ the carbon fiber bundle was used in the weft direction (enhancement direction) and the glass fiber bundle was used in the warp direction (fixation direction). The spacing of the fiber bundle was 10 mm × 10 mm. The mechanical properties are shown in Table 2. The literature⁶ suggested that the textile impregnated with epoxy resin and covered with sand had better effective confining ability, which could make full use of the crack-limiting and enhancement effect of the TRC reinforcement layer. In this experiment, all textiles were impregnated with epoxy resin and covered with sand. The weft direction was the main force direction, and so this article only provided the physical and mechanical parameters of the carbon yarn, which are shown in Table 3.

Table 2.

Mechanical properties of textile.

Fiber type	No. of filaments in yarn	Tensile strength (MPa)	Modulus of elasticity (GPa)	Ultimate strain (%)	Linear density (tex)	Density (g/cm³)
T700S	12,000	4660	231	2	801	1.78
E-glass	4000	3200	65	4.5	600	2.58

Table 3.

Mechanical properties of weft carbon yarn with epoxy resin impregnated.

Fiber type	No. of fibrils per bundle	Tensile strength (MPa)	Theoretical area (mm²)	Linear density (tex)	Density (g/cm³)
T700S	12,000	4100	0.45	801	1.78

Fine-grained concrete

The mix proportion of fine-grained concrete provided by the literature¹³ was cement:fly ash:silica fume:water:fine sand:coarse sand:water reducer = 475:168:35:262:460:920:9.1, respectively. The average strength measured after curing the concrete cube standard test block of 70.7 mm × 70.7 mm × 70.7 mm for 28 days was 52.5 MPa.

Chopped fiber

Polyvinyl alcohol (PVA) and AR-glass chopped fiber were used in the experiment, and the geometric parameters and mechanical properties are shown in Table 4.

Table 4.

Properties and geometric parameters of chopped fibers.

Type	Length (mm)	Diameter (µm)	Tensile strength (MPa)	Elastic modulus (GPa)	Density (kg/m³)	Volume content
PVA	12	40	1600	42	1.3	0.5%
AR glass	12	15	1700	72	2.7	0.5%

PVA: polyvinyl alcohol; AR: alkali resistant.

Reinforcement scheme

According to the reinforcement form of TRC, the scheme can be divided into the following two methods: cast-in-place and prefabricated reinforcement. The cast-in-place TRC can be divided into the following steps: first, the bottom surface of the beam was roughened and cleaned; roughening was done to increase the surface roughness, thereby enhancing the bonding performance between TRC and old concrete. Second, the beam was subjected to four-point bending loading with a load ratio of 0.2 (the load ratio is the ratio of the sustained load to the ultimate load of the unreinforced beam, which was obtained by calculating).¹⁴ Third, planks were placed on both sides of the beam and fixed with fixtures, keeping the edges of planks flush with the beam surface. Fourth, fine-grained concrete of 2–3 mm was evenly smeared on the surface of old concrete, and then, textile was laid and fixed on both sides of the planks using 3-mm wooden strip for controlling the total thickness of the reinforcement layer to be 10 mm. Fifth, the third step was repeated and the surface of the reinforcement layer was smoothed evenly. After reinforcement was completed, the beam bottom was covered with a plank, and the fixtures were used to tighten the connection to prevent falling of the reinforcement layer due to the weight of TRC, which would affect the interfacial performance between TRC and old concrete. The reinforcement diagram is shown in Figure 2.

Figure 2.

Reinforcement diagram: (a) picture of casing and (b) casing sketch under sustained load.

The prefabricated reinforcement can be divided into the following steps: first, the TRC reinforcement layer was prefabricated in advance, and the thickness of the prefabricated panel was controlled to be approximately 8 mm. The first, second, and third steps were then repeated for the cast-in-place reinforcement. Then, 2–3 mm of fine-grained concrete was evenly smeared on the surface of old concrete and the prefabricated panel was laid.

Chloride environment

The sustained load was removed after TRC was cured for 28 days under room temperature and the humidity of no less than 95%. Then, the marine environment was simulated, and a dry–wet cycle with chloride salt was carried out. The simulation system is as follows:¹³ after immersion in 5% sodium chloride solution for 12 h under room temperature and the humidity of 45%–75%, the chloride salt solution was drained and the specimens were dried for 12 h (using fans for assistance, which is equivalent to simulate sea breeze). This was a complete dry–wet cycle lasting for 24 h.

Loading mode and test content

After the specimens dried completely, the four-point bending loading mode was adopted. The upper part of the jack was a pressure sensor, and the loaded values were read through the display. To verify the plane section assumption, concrete strain gauges were attached to the mid-span part of the specimen; one gauge was installed on the top and four gauges were installed on the side at the distances of 40, 80, 120, and 160 mm from the top of the beam. The mid-span deflection and the fulcrum deformation were measured via a displacement meter. In addition, the steel strain gauges were attached to the middle part of the longitudinal tension reinforcement for judging the yield of the steel bar. During loading, the loading grade was 5 kN, and at 3–5 min after each loading, cracks were observed and the maximum crack width was measured. The DH-3816 static acquisition equipment produced by Jiangsu Donghua Test Co., Ltd. was used for the data acquisition. The crack width was measured via a crack width tester produced by Beijing Earth Long Science and Technology Co., Ltd., with an accuracy of 0.02 mm.

Experimental results and analysis

The cracking load P_cr, yield load P_y, and ultimate load P_u of the specimens are summarized in Table 5. Δ_cr, Δ_y, and Δ_u are the mid-span deflections corresponding to the cracking, yield, and ultimate load, respectively.

Table 5.

Summary of experimental results.

Number	P_cr/kN	Δ_cr/mm	P_y/kN	Δ_y/mm	P_u/kN	Δ_u/mm	Failure mode
H1	13.5	0.56	129	4.90	148	10.41	Textile snapped
H2	11.1	0.53	128	5.26	142	9.29	Textile snapped
H3	9.8	0.30	114	6.31	131	10.91	Partial debonding
H4	10.2	0.35	119	4.46	137	9.36	Partial debonding
H5	13.9	0.39	134	5.06	149	9.86	Textile snapped
H6	14.8	0.39	132	4.59	151	11.25	Textile snapped

Failure characteristics and crack analysis

In the experiment, the textile of all beams had tensile failure, and the concrete in the compression zone was finally crushed. There are two failure modes, including TRC and old concrete bonded together and cracks generated along the longitudinal steel bars. This is due to the good bonding between TRC and the old concrete, which is better than the bonding between the old concrete and steel bars; the yield of the steel bars also led to the weakening of the latter, as shown in Figure 3(a). Another failure mode is the partial debonding of TRC, as shown in Figure 3(b). That is because, on one hand, the load before reinforcement makes the beams have deflection deformation, and the beams have certain deformation recovery after unloading, which causes certain interaction between TRC and the old concrete, leading to the shearing force which weakens the interfacial bonding performance. On the other hand, the interfacial performance is reduced due to the effect of the dry–wet cycle and chloride corrosion, which make the interface between TRC and old concrete generate more microcrack.

Figure 3.

Failure modes of beams: (a) textile snapped and (b) partial debonding.

Different dry–wet cycle numbers

Beams H1 and H2 have the failure mode shown in Figure 3(a), while beam H3 has the failure mode shown in Figure 3(b). The partial debonding of beam H3 may be due to the increase of the dry–wet cycle numbers, which leads to the increase of holes and microcracks in the interfacial microstructure between TRC and the old concrete, decreasing the interfacial bonding performance. Meanwhile, chlorine salt crystallizes and corrosion products are produced in the concrete. With the increase of the dry–wet cycle numbers, the corrosion time increases and the corrosion products increase, resulting in internal expansion stress, which causes deterioration of the concrete performance.¹⁵ As seen from Figure 4(a), the crack width development of the three beams is almost the same before a certain load, and in the later stage, due to the partial debonding of beam H3, the crack-limiting performance of TRC is reduced, making the crack develop faster and with a width larger in the later stage.

Figure 4.

Load-maximum crack width diagram of beams: (a) H1, H2, H3 and H4 and (b) H2, H5 and H6.

Different reinforcement methods

Beam H4 has the failure mode shown in Figure 3(b). On one hand, because the beam was reinforced with a sustaining load, it has a certain deflection before strengthening, and the prefabricated board is a whole, and so the interfacial bonding between TRC and the old concrete is damaged after unloading. On the other hand, the surface roughness of the prefabricated TRC board is lower, which reduces the interfacial bite force. The damage accumulates after the dry–wet cycle and chloride corrosion, affecting the interfacial performance to a certain extent. It can be seen from Figure 4(a) that the crack-limiting ability of the prefabricated panel reinforced beam is similar to the cast-in-place reinforced beam; however, in the later stage of loading, the control ability of prefabricated panel to crack decreases and the crack develops faster a little. On the whole, however, the prefabricated TRC board can also play a good role in structural reinforcement.

Chopped fiber content

Beams H5 and H6 have the failure mode shown in Figure 3(a). As seen from Figure 4(b), at the same loading level, the maximum crack width of beams H5 and H6 is smaller than that of beam H2, and the crack development is slower. This result indicates that the crack-limiting ability of beams H5 and H6 is better than that of H2, especially in the later stage of loading. This is because the fiber plays a bridge role, which contributes to the stress transfer at the surface between textile and fine-grained concrete and reduces the stress concentration at the crack tip, limiting the concrete cracking. Moreover, the fiber addition can improve the pore structure and reduce the internal porosity of the concrete, which makes its structure denser; therefore, the resistance of TRC to chloride ion permeation is improved, alleviating the deterioration caused by chloride erosion.¹⁶

Bearing capacity analysis

Different dry–wet cycle numbers

With the increase of dry–wet cycle numbers, the cracking, yield, and ultimate load of beams decrease, as shown in Table 5. Compared with beam H1, the cracking load of beam H3 decreases by 27.41%, the yield load decreases by 11.63%, and the ultimate load decreases by 11.49%. On one hand, as described in section “Different dry–wet cycle numbers” under “Failure characteristics and crack analysis,” with the increase of dry–wet cycle numbers, the interfacial bonding performance between TRC and old concrete decreases. On the other hand, microcracks generate inside the concrete when the beam has a reinforced sustaining load, which promotes the penetration and erosion of chloride ions, making the concrete performance decrease; therefore, the bearing capacity of reinforced beam is affected. From the perspective of the failure mode of beam H3, the partial debonding causes the TRC reinforcement layer to not play its full role, affecting the improvement of bearing capacity.

Different reinforcement methods

It can be seen from Table 5 that, compared with beam H2, the cracking load of beam H4 decreases by 8.11%, the yield load decreases by 7.03%, and the ultimate load decreases by 3.52%. As explained in section “Different reinforcement methods” under “Failure characteristics and crack analysis,” the unloading after sustaining load has a certain influence on the interfacial bonding performance between a prefabricated TRC panel and old concrete, and the dry–wet cycle with chloride weakens the bonding force further, decreasing the reinforcement effect of TRC to some extent. It can also be seen from the failure mode of beam H4 that, in the later stage, the textile is snapped and then the middle part exfoliates, which indicates that the bonding performance is worse than that of cast-in-place TRC, decreasing the ultimate bearing capacity of beam H4.

Chopped fiber content

As shown in Table 5, the cracking, yield, and ultimate load of reinforced beams increases with the addition of chopped fiber and the cracking load increases more. Compared with beam H2, the cracking loads of beams H5 and H6 increase by 25.23% and 33.33%, respectively. As explained in section “Chopped fiber content” under “Failure characteristics and crack analysis,” the addition of chopped fiber can improve the interfacial performance between the textile and the fine-grained concrete as well as alleviate the erosion of chloride ions, improving the role in reinforcement of TRC and limiting the concrete cracking. Therefore, the beam damage is delayed, which greatly increases the bearing capacity.

Load–mid-span deflection analysis

Different dry–wet cycle numbers

It can be seen from Figure 5(a) that, under the same load, as the dry–wet cycle numbers increase, the mid-span deflection of the beam increases. As explained in section “Different dry–wet cycle numbers” under “Failure characteristics and crack analysis,” with the increase of dry–wet cycle numbers, the bonding performance between TRC and old concrete decreases, which affects the reinforcement effect of TRC and accelerates the deterioration of concrete affected by chloride erosion, decreasing the stiffness of reinforced beams. Therefore, the mid-span deflection of the beam develops relatively faster. In particular, the mid-span deflection of beam H3 has the fastest development, and it can also be seen from the failure mode of beam H3 that the poor bonding performance between TRC and old concrete finally causes partial debonding. However, it can be seen from the deflection curves of the three beams shown in Figure 5(a) that TRC can still limit the mid-span deflection variation better before the yield of steel bars.

Figure 5.

Load-mid-span deflection diagram of beams: (a) H1, H2, H3 and H4 and (b) H2, H5 and H6.

Different reinforcement methods

As shown in Figure 5(a), the two deflection curves are almost the same, but the beam reinforced with prefabricated TRC yields earlier, which results in the quick change of the deflection curve after the steel bars yield. From the viewpoint in section “Different reinforcement methods” under “Failure characteristics and crack analysis,” the interfacial performance between the prefabricated TRC panel and old concrete is poorer, which limits the reinforcement role of TRC in the later stage, thus affecting the limiting effect of TRC on deflection, and the deflection of the reinforced beam changes greatly. However, the overall deflection curves of the two are not much different, and so from the perspective of deflection, the prefabricated TRC reinforcement method is also suitable.

Chopped fiber content

It can be seen from Figure 5(b) that, under the same load, the deflection of beams H5 and H6 is smaller than that of beam H2 and the change is relatively slower. As explained in section “Chopped fiber content” under “Failure characteristics and crack analysis,” the addition of chopped fiber can improve the reinforcement effect of TRC and improve the crack-limiting ability of the reinforced beam, thus delaying the deterioration of concrete and better controlling the descending process of stiffness. From the failure mode of the beam shown in Figure 6, it can be observed that the crack of beams H5 and H6 is more and dense and the upward extension is longer, which indicates that the TRC plays a better role in limiting cracking, better controlling the beam deflection.

Figure 6.

Failure modes of beam: (a) H5 and (b) H6.

Bearing capacity calculation of TRC-reinforced beam with a secondary load

Ultimate load analysis

In some practical engineering studies of reinforcing beam structures, due to the environmental constraints, some residual load will exist on the upper part of the beam during reinforcement, which will make the beam produce certain initial stress and deflection. Compared with the original component, the reinforcement layer has certain strain lag after reinforcement, which has certain impact on the reinforcement effect. Therefore, it must be considered in the calculation in order to be more in line with the actual project. Referring to previous literature,¹⁷ the initial strain $ε_{i}$ is determined according to $α_{f}$ and the initial bending moment, as shown in formula (1), which is used to determine the post-strain of the textile

ε_{f 0} = \frac{α_{f} M_{i}}{E_{s} A_{s} h_{0}}

(1)

where $ε_{f 0}$ is the post-strain of the textile, $M_{i}$ is the initial bending moment, $E_{s}$ is the elastic modulus of steel bar, $A_{s}$ is the section area of tensile steel bar, $h_{0}$ is the effective section height, and $α_{f}$ is a calculation influence coefficient, which is determined to be 0.975 according to the literature.¹⁷

According to the literature,¹⁸ the nominal tensile strain of textile is defined as $ε_{f n}$ , and then, the nominal tensile strain of textile is the actual strain $ε_{f}$ plus the post-strain $ε_{f 0}$ . The nominal tensile strain can be obtained from the plane section assumption,¹⁸ and thus, the actual tensile strain of the textile can be obtained as follows

ε_{f} = ε_{f n} - ε_{f 0}

(2)

Then, according to the actual strain of the textile, the actual stress $σ_{f}$ is obtained. Referring to the calculation theory of a previous study,¹⁸ the formula for calculating the ultimate load of the TRC-reinforced beam with a secondary load is obtained, as shown in formula (3)

M_{u} = f_{y} A_{s} (h_{0} - \frac{x}{2}) + λ σ_{f} A_{f} (h + \frac{t_{f}}{2} - \frac{x}{2})

(3)

where $f_{y}$ is the standard value of the measured tensile strength of the steel bar, $x$ is the height of the concrete compression zone, $A_{f}$ is the section area of textile, $h$ is the height of the beam, $t_{f}$ is the thickness of the TRC reinforcement layer, and $λ$ is the environmental influence coefficient introduced by considering the effect of the dry–wet cycle. It is determined that $λ = 3.72 - 0.012 N$ ( $N$ is the dry–wet cycle number) by referring to the literature.¹⁹

Comparison of theoretical and experimental values

The stress lag is introduced into the calculation, and beams H1, H2, and H3 experiencing different dry–wet cycle times are used for verification, as shown in Table 6.

Table 6.

Comparison of sustained load beam theoretical and experimental values.

Number	Calculated value (kN)	Actual value (kN)	Calculated value/actual value
H1	151.21	148	1.02
H2	145.89	142	1.03
H3	140.59	131	1.07

It can be seen from Table 6 that the error between the calculated value and the actual value of specimen is small, which indicates that the calculation formula can better calculate the ultimate load value of the TRC-strengthened beam with a secondary load under different dry–wet cycle numbers. As shown in Table 6, the error of beam H3 is the greatest, which may be because beam H3 is damaged as a result of sustaining load before reinforcement and the dry–wet cycle numbers are greater. These factors have great influence on the interfacial performance between TRC and old concrete, making the beam become partially debonded, and so the bearing capacity of the beam is greatly affected.

Conclusion

With the increase of dry–wet cycle numbers, the crack width and deflection of beams with a secondary load increases and the bearing capacity decreases. The overall change range is lower; therefore, TRC is suitable for reinforcing damaged beams under a chloride environment.

When the prefabricated TRC panel is reinforced to the bottom of the beam, its performance in limiting crack, bearing capacity, and deflection is close to that of cast-in-place reinforced beams in the early stage, but it is a little insufficient in the later stage.

The addition of chopped fiber has a good modification effect on TRC, which improves the crack-limiting performance of TRC and improves the reinforcement role played, which in turn improves the overall performance of the beam with a secondary load.

Based on the experimental results, the calculation formula of bearing capacity of TRC-strengthened beams with a secondary load under chloride erosion is established, and the calculated values are in good agreement with the actual values. For practical application however, much experimental verification is needed.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was funded by the Fundamental Research Funds for the Central Universities (grant no. 2017XKZD09).

ORCID iD

Shiping Yin

References

Gjorv

OE.

Durability design of concrete structures in severe environments. 2nd ed. Boca Raton, FL: CRC Press, 2014, pp. 629–630.

Deng

Liu

et al . Interfacial behavior of RC beams strengthened with FRP under fatigue loading. Adv Struct Eng 2015; 18(2): 283–293.

Chotickai

Somana

Performance of CFRP-strengthened concrete beams after exposure to wet/dry cycles. J Compos Constr 2018; 22(6): 04018053.

Zhu

Liao

Zheng

et al . Experimental study on RC beams’ bending capacity strengthened with CFRP considering secondary load. Build Struct 2010; 2: 379–381 (in Chinese).

D’Ambrisi

Focacci

Flexural strengthening of RC beams with cement-based composites. J Compos Constr 2011; 15(5): 707–720.

Yin

Wang

Investigation on the flexural behavior of concrete members reinforced with epoxy resin-impregnated textiles. Mater Struct 2015; 48(1–2): 153–166.

Larbi

Agbossou

Hamelin

Experimental and numerical investigations about textile-reinforced concrete and hybrid solutions for repairing and/or strengthening reinforced concrete beams. Compos Struct 2013; 99: 152–162.

Contamine

Larbi

AS.

Development of a textile reinforced concrete (TRC) to retrofit reinforced concrete structures. Eur J Environ Civ En 2016; 20(6): 626–642.

Verbruggen

Tysmans

Wastiels

Bending crack behaviour of plain concrete beams externally reinforced with TRC. Mater Struct 2016; 49(12): 5303–5314.

10.

Truong

Bui

Limam

Experimental investigations of reinforced concrete beams repaired/reinforced by TRC composites. Compos Struct 2017; 168: 826–839.

11.

Xun

Experimental research on secondary bending behavior of reinforced concrete beams strengthened with textile reinforced concrete sheets. Ind Constr 2015; 45(1): 173–178 (in Chinese).

12.

Gopinath

Murthy

Iyer

et al . Investigations on textile-reinforced concrete as cover for RC beams. Mag Concrete Res 2016; 68: 1040–1050.

13.

Yin

Sheng

Wang

et al . Experimental investigations of the bending fatigue performance of TRC-strengthened RC beams in conventional and aggressive chlorate environments. J Compos Constr 2016; 20(2): 04015051.

14.

Sheng

Yin

Wang

et al . Experimental study on the fatigue behaviour of RC beams strengthened with TRC after sustained load corrosion. Constr Build Mater 2017; 131: 713–720.

15.

Wang

Corrosion damage of concrete under multi-salt soaking, freezing-thawing and dry-wet cycles. J Jilin Univ 2015; 45: 112–120 (in Chinese).

16.

Huang

Shi

Wang

et al . The influence of fiber on the resistance to chloride-ion penetration of concrete under the environment of carbonation. Mater Rev 2015; 2: 546–549 (in Chinese).

17.

Ouyang

Wang

Zhang

YC.

Calculation and analysis of flexural and shear capacity of RC beams strengthened with BFRP sheets. Ind Constr 2007; 37(6): 24–27 (in Chinese).

18.

Yin

Flexural behavior of reinforced concrete beams with TRC tension zone cover. J Mater Civil Eng 2014; 27: 4320–4330.

19.

Yin

et al . Axial compression performance of reinforced concrete column strengthened with TRC under chloride dry-wet cycles. China J Highway Transport 2017; 30(6): 230–238 (in Chinese).

Flexural properties of load-holding reinforced concrete beams strengthened with textile-reinforced concrete under a chloride dry–wet cycle

Abstract

Keywords

Introduction

General experimental situation

Specimen design

Concrete

Steel bar

Textile

Fine-grained concrete

Chopped fiber

Reinforcement scheme

Chloride environment

Loading mode and test content

Experimental results and analysis

Failure characteristics and crack analysis

Different dry–wet cycle numbers

Different reinforcement methods

Chopped fiber content

Bearing capacity analysis

Different dry–wet cycle numbers

Different reinforcement methods

Chopped fiber content

Load–mid-span deflection analysis

Different dry–wet cycle numbers

Different reinforcement methods

Chopped fiber content

Bearing capacity calculation of TRC-reinforced beam with a secondary load

Ultimate load analysis

Comparison of theoretical and experimental values

Conclusion

Footnotes

Declaration of conflicting interests

Funding

ORCID iD

References