Research Article  Open Access
Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data
Abstract
Reinforcement corrosion is a major cause of degradation in reinforced concrete structures. The fragile rust layer and cracking and spalling of the cover caused by splitting stress due to rust expansion can alter bond behaviors significantly. Despite extensive experimental tests, no stochastic model has yet incorporated randomness into the bond parameters model. This paper gathered published experimental data on the bondslip parameters of pullout specimens and beamend specimens. Regression analysis was carried out to identify the best fit of bond strength and the corresponding slip value in the context of different corrosion levels from the recollected test results. An test confirmed the regression effect to be significant. Residual data were also analyzed and found to be well described by a normal distribution. Crack width data of the tested specimens were also collected. A regression analysis of the bond strength and maximum crack width was carried out given the comparative simplicity of measuring crack width versus rebar area loss. Results indicate that maximum crack width can also be used to predict bond strength degradation with similar variation magnitude.
1. Introduction
The civil engineering field generally accepts that reinforced concrete structures possess durability problems. One of the harshest environments for concrete structures is the marine environment, as it contains corrosive chloride ions [1]. Chloride ions can diffuse into concrete, accumulate at the reinforcement surface, and depassivate the protective layer. Corrosion of reinforcement occurs when chlorides surpass a threshold value; it is the main cause of performance degradation in aged concrete structures. Corrosion products of reinforcement expand in volume with a strength much lower than that of steel, reducing the effective reinforcement area. Expansion of reinforcement rust can also lead to cracking and spalling of the concrete cover when expansion stress surpasses the tensile strength of concrete [2].
The effects of reinforcingbar corrosion on bond behaviors have been widely studied by many scholars [3–7] for over 30 years using different test setups. Abdullah et al. [8] studied the bond behavior of reinforced concrete members including ultimate bond strength, freeend slip, and failure modes in the precracking, cracking, and postfracture stages. Fang et al. [9] conducted a pullout test to evaluate the effects of corrosion on bond and bondslip behavior in specimens with and without stirrups that provided confinement. Wei et al. [10] designed beamend specimens to study the bond between corroded steel and concrete. However, bond strength reduction due to the fragile corrosion products between concrete and steel has been often neglected in the field.
The research disparity persists between industry and academia in the absence of a unified and feasible model that considers the degradation of bond behaviors. Several factors influence bond performance and the complex nature of interface behaviors between concrete and reinforcement, especially when accounting for the effects of reinforcement corrosion [11]. The roughness of the reinforcement surface and confinement of concrete have been shown to exert significant effects on bond performance. Rebar corrosion can certainly change the surface between rebar and concrete; the expansion of corrosion products can also lead to cracking and spalling of the concrete cover, thus degrading confinement. Recent studies [12, 13] have revealed that stirrup corrosion can also degrade the confinement of rebar and concrete, potentially altering the bond failure type, strength, and ductility of confined concrete. In some research, these factors are considered collectively; as experiments often implement different test setups [9, 14], the results of each test are often unique. Additional studies on the effects of corrosion on bond parameters are necessary to further develop a widely applicable bondslip model for assessment of corroded reinforcement concrete structures.
This preliminary study recollected the test data on bond strength and corresponding slip value and maximum crack width from published literatures. Regression analysis was applied to obtain the best fit for the above three parameters. An test [15] was carried out to verify the regression analysis results. Residuals were also analyzed and modeled as a normal distribution to consider variation in bond behaviors.
2. Pullout Specimens
Two different rebars were used for pullout specimen tests: plain rebar (Table 1) and deformed rebar (Table 2). These two types of rebar exhibit different bond behaviors; the rib of deformed rebar can hook to concrete and change the stress field around the rebar and concrete interface, whereas plain rebar bonds have no similar working mechanism. Each type will be discussed separately in the following sections.


2.1. Plain Rebar
2.1.1. Dimensionless Bond Strength
Table 1 lists the collected test parameters, where is the rebar diameter, is the concrete cover depth, and is the bond length. “” indicates the parameter was not reported in the literature. As setups involved test specimens with different levels of concrete strength, dimensionless bond strength was used in this paper. The dimensionless bond strength of a corroded rebar was defined as , where and denote the tested bond strength of corroded steel and noncorroded steel, respectively. In tests with more than one noncorroded specimen, represents the mean value of the bond strength of the tested noncorroded specimens.
Figure 1(a) shows the recollected test results of dimensionless bond strength and corresponding corrosion level (the mean rebar mass loss is identical to area loss). Nonlinear regression analysis of the test data included the following equation:where is the proportion (i.e., percentage) of the extent of steel corrosion. is 0.445, and is the coefficient of determination, interpreted as the proportionate reduction in total variation associated with the predictor variable; the closer it is to 1, the greater the degree of association between the predictor and response variables. As shown in Figure 1(a), the dimensionless bond strength first increased and then decreased with an increase in corrosion level.
(a) Dimensionless bond strength versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless bond strength
An test was further applied to test the significance of the regression curve:where is the explained sum of squares, is the residual sum of squares, is the predicted value corresponding to the abscissa, is the average of all predicted values, is the value of dimensionless bond strength, and is the total number of data. When is greater than , the regression effect is considered significant at .
The value of pullout specimens with plain rebar was 21.0, greater than the corresponding at a significance level of ; hence the regression effect was significant. The bond between corroded steel bars and concrete is also affected by other factors, such as concrete strength, protective layer thickness, the existence of stirrups, the diameter of corroded steel bars, and test setup. The central limit theorem states that, under some conditions (including finite variance), the averages of sample observations of random variables drawn from independent distributions converge in a normal distribution; that is, they become normally distributed when the number of observations is sufficiently large. In the present study, dimensionless values have also been used to try to eliminate the effects of these factors; residuals were further assessed to verify the above assumption. Figure 1(b) plots the residuals after nonlinear regression analysis; the residuals are distributed randomly along the horizontal axis. Figure 1(c) presents a histogram of the distribution of residuals, which appear to fit a normal distribution with a mean value () of 0.00738 and standard deviation () of 0.355. The regression formula and normal distribution of residuals will be applied to model the bonds of corroded plain rebar and concrete later in this paper.
2.1.2. Dimensionless Slip Value Corresponding to Bond Strength
Given different setups of test specimens with different levels of concrete strength, the dimensionless slip value corresponding to bond strength was studied as follows. The dimensionless slip value corresponding to bond strength of corroded rebar was defined as , where and are the slip values corresponding to the bond strength of corroded steel and noncorroded steel, respectively. In cases with more than one noncorroded specimen, denotes the mean value of the noncorroded specimens as that of bond strength.
Figure 2(a) shows the variation in dimensionless slip value corresponding to bond strength at certain corrosion levels. Nonlinear regression analysis of the test data employed the following equation: is 0.540, indicating the existence of unexplained factors. Figure 2(b) shows that the residuals are randomly distributed along the horizontal axis on the negative and positive sides. Figure 2(c) indicates the residual data is well fitted by a normal distribution with an expectation () of 0.0133, which is close to zero, and a standard deviation () of 0.263.
(a) Dimensionless slip value versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless slip value
2.2. Deformed Rebar
Table 2 shows collected references of pullout tests with deformed rebars. Deformed rebar specimens can be divided into two subgroups: with and without stirrups. As confinement can change bond behaviors significantly, these subgroups will be discussed separately in subsequent sections. Stirrup density can also affect the bond properties of corroded steel bars. However, because stirrup density was randomly distributed in these tests, it was not considered in this preliminary study; a dimensionless value was used in relevant analyses instead.
2.2.1. Dimensionless Bond Strength without Stirrups
Figure 3(a) shows the variation in dimensionless bond strength at different corrosion levels. Nonlinear regression analysis of the test data applied the following equation: is 0.384. The value of pullout specimens with deformed rebar (i.e., no stirrups) was 187, while the corresponding critical value was 6.72 at a significance level of . Thus, the regression effect was significant, and the residuals could be analyzed.
(a) Dimensionless bond strength versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless bond strength
Figure 3(b) illustrates that the residuals are distributed randomly around the horizontal axis. Figure 3(c) displays a histogram of residuals on a curve fitted with a normal distribution with a mean value () of 0.000425 and standard deviation () of 0.253, suggesting the residual data fit the proposed normal distribution well.
2.2.2. Dimensionless Slip Value Corresponding to Bond Strength without Stirrups
Figure 4(a) shows the dimensionless slip value corresponding to bond strength compared to the corrosion level. The nonlinear regression analysis of the test data used the following equation:The corresponding is 0.377. Figure 4(b) shows the residuals are nearly symmetrically distributed along the horizontal axis. Figure 4(c) presents the histogram of the residuals, which fit a normal distribution well with expectations () of 0.00110, which is close to zero, and a standard deviation () of 0.234.
(a) Dimensionless slip value versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless slip value
2.2.3. Dimensionless Bond Strength with Stirrups
Figure 5(a) shows the variation in dimensionless bond strength with the corrosion level. The nonlinear regression analysis of the test data employed the following equation: is 0.505. The value of pullout specimens with a deformed rebar (stirrups) was 211, larger than the corresponding critical value of 6.76 at a significance level of . Thus, the regression effect was significant, and the residuals could be analyzed.
(a) Dimensionless bond strength versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless bond strength
Residuals are shown in Figure 5(b), randomly distributed well along the horizontal axis. Figure 5(c) plots the histogram of the residuals and indicates they fit with a normal distribution. The expected value () is nearly zero (0.0000770), and the standard deviation () is 0.190.
2.2.4. Dimensionless Slip Value Corresponding to Bond Strength with Stirrups
Figure 6(a) illustrates the variation in dimensionless slip value corresponding to bond strength with the corrosion level. Nonlinear regression analysis of the test data involved the following equation: is 0.224, relatively smaller than the previously mentioned cases, presumably due to highly scattered data. Figure 6(b) shows that the residuals are also nearly symmetrically distributed along the horizontal axis. Figure 6(c) presents the histogram of the residuals fitting to a normal distribution with a mean value () of 0.0242 and standard deviation () of 0.274.
(a) Dimensionless slip value versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless slip value
3. BeamEnd Specimens
3.1. Dimensionless Bond Strength
Table 3 lists the collected beamend tests. Figure 7(a) shows the variation in the dimensionless bond strength of beamend specimens by corrosion level. The nonlinear regression analysis of the test data employed the following equation: is 0.422. The values of beamend specimens confirmed the regression effect was significant, and the residuals could be analyzed. Figure 7(b) plots the residuals after nonlinear regression analysis, randomly distributed along the horizontal axis. Figure 7(c) is the histogram of the residuals, which fit a normal distribution well. The expected value () is 0.000970, and the standard deviation () is 0.170.

(a) Dimensionless bond strength versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless bond strength
3.2. Dimensionless Slip Value Corresponding to Bond Strength
Figure 8(a) shows the variation in dimensionless slip value corresponding to bond strength with the corrosion level of the beamend specimens. The nonlinear regression analysis of the test data shows the following equation:The corresponding is 0.402. Residuals analysis suggested they are randomly distributed well along the horizontal axis as shown in Figure 8(b). Figure 8(c) provides the histogram of the residuals, which were well fitted to a normal distribution with a mean value () of 0.00488, close to zero, and standard deviation () of 0.215.
(a) Dimensionless slip value versus corrosion level
(b) Residuals versus corrosion level
(c) Histogram of residuals of dimensionless slip value
4. Discussions
The above regression analysis outlines the degradation of bond parameters based on the measured rebar corrosion level. In engineering practice, it is nearly impossible to measure rebar area loss without structural damage to the site; however, crack width can be easily measured without resultant damage. Fortuitously, many recollected test results also recorded the maximum crack width involved in rebar corrosion. Figures 9(a) and 10(a) show dimensionless bond strength degradation with an increase in maximum crack width. The two different specimens, pullout and beamend, were discussed individually. The dimensionless bond strength clearly decreased as maximum crack width increased. The regression analysis involved the following formula for degradation:where is the maximum crack width. The corresponding values are 0.231 and 0.397 for pullout specimens and beamend specimens, respectively. The mean value () and standard deviation () of the residuals are 0.00304 and 0.297 (see Figure 9(c)) for pullout specimens. The mean value () and standard deviation () of the residuals are 0.0142 and 0.193 (see Figure 10(c)) for beamend specimens. Results confirmed that the crack opening could serve as an index to stochastically evaluate bond strength degradation.
(a) Dimensionless bond strength versus maximum crack width
(b) Residuals versus maximum crack width
(c) Histogram of residuals of dimensionless bond strength
(a) Dimensionless bond strength versus maximum crack width
(b) Residuals versus maximum crack width
(c) Histogram of residuals of dimensionless bond strength
From the above studies, the degradation of dimensionless bond parameters can be modeled by the following stochastic process:where parameters , , , , , , , , and are the variables determined from regression analysis and is the normal distribution of residuals. Variables and standard deviations are listed in Table 4. The above analysis was based on recollected data indicating a general area loss of less than 20%; as such, these results are only applicable to corrosion levels below 20%. Additional data are still needed to refine the proposed formulas.

5. Conclusions
This paper carried out nonlinear regression analysis of recollected test data on bond strength, corresponding slip value, and crack width following rebar corrosion. Four different test groups were discussed: pullout tests of plain rebars, pullout tests of deformed rebars with stirrup confinement, pullout tests of deformed rebars without stirrups, and beamend specimens. An test indicated the regression formulas were significant. The residuals were further analyzed and fitted by normal distributions. Unified formulas for a stochastic process describing dimensionless bond strength, corresponding slip value as corrosion level, and maximum crack width increases were proposed. Our findings suggest the following:(1)Regarding dimensionless bond strength of plain bars, the regression formula indicates the bond strength first increased significantly and then decreased as the corrosion level increased. Maximum dimensionless bond strength was reached at an approximate corrosion level of 1.5%. Bond strength varied significantly, showing a standard deviation () of 0.355. The dimensionless slip value decreased as the corrosion level increased.(2)For deformed rebars of pullout specimens and beamend specimens, the regression analysis revealed the dimensionless bond strength initially degraded slightly as rebar corroded and then degraded significantly as the corrosion level continued to rise. Clear bond strength variations appeared between specimens with and without stirrups. As the corrosion level increased, the dimensionless slip value declined significantly.(3)The dimensionless bond strength could also be predicted from the maximum crack width. Regression analysis showed the crack opening could serve as an index to stochastically evaluate bond strength degradation.
This paper represents a preliminary study based on recollected test specimens with a corrosion level below 20% (i.e., the proposed formula applies only to specimens with a corrosion level lower than 20%). The standard deviations reported in this paper were large in some cases, requiring additional experimental tests to further calibrate and improve the proposed formulas.
Data Availability
The collected data that support the findings of this study are available from the corresponding author, L. X. Li, upon reasonable request.
Conflicts of Interest
The authors declare that there are no conflicts of interest regarding the publication of this paper.
Acknowledgments
The work described in this paper was financially supported by the National Natural Science Foundation of China (Grant no. 51378313) and the Ministry of Science and Technology for the 973project (no. 2011CB013604). The first author gratefully acknowledges the support of the China Scholarship Council for a 1year visit as a visiting research scientist in the Department of Civil Engineering and Engineering Mechanics, Columbia University.
References
 M. M. S. Cheung, K. K. L. So, and X. Q. Zhang, “Life cycle cost management of concrete structures relative to chlorideinduced reinforcement corrosion,” Structure Infrastructure Engineering, vol. 8, no. 12, pp. 1136–1150, 2012. View at: Google Scholar
 I. Khan, R. François, and A. Castel, “Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams,” Cement and Concrete Research, vol. 56, pp. 84–96, 2014. View at: Publisher Site  Google Scholar
 W. Jin, “Effect of corrosion on bond behavior and bending strength of reinforced concrete beams,” Journal of Zhejiang University Science A, vol. 2, no. 3, p. 298, 2001. View at: Publisher Site  Google Scholar
 Y. X. Zhao and W. L. Jin, “Test study on bond behavior of corroded steel bars and concrete,” Journal of Zhejiang University (Engineering Science), vol. 36, no. 4, pp. 352–356, 2002 (Chinese). View at: Google Scholar
 Y. C. Xv, Research on bond performance between the rusted bar and concrete by pullout tests, Huazhong University of Science Technology, 2006.
 C. M. Li, Experimental study on bond properties of nonuniformly corroded bar and concrete, North China University of Water Resources and Electric Power, 2012.
 F. Tondolo, “Bond behaviour with reinforcement corrosion,” Construction and Building Materials, vol. 93, pp. 926–932, 2015. View at: Publisher Site  Google Scholar
 A. A. Almusallam, A. S. AlGahtani, and A. R. Aziz, “Effect of reinforcement corrosion on bond strength,” Construction and Building Materials, vol. 10, no. 2, pp. 123–129, 1996. View at: Publisher Site  Google Scholar
 C. Fang, K. Lundgren, L. Chen, and C. Zhu, “Corrosion influence on bond in reinforced concrete,” Cement and Concrete Research, vol. 34, no. 11, pp. 2159–2167, 2004. View at: Publisher Site  Google Scholar
 J. Wei, H. Zhang, G. Xv et al., “Experimental Study on the bond behavior between concrete and corroded steel bars,” Journal of Railway Science and Engineering, vol. 6, no. 4, pp. 28–31, 2009 (Chinese). View at: Google Scholar
 H. Zhou, J. Lu, X. Xv, Y. Zhou, and F. Xing, “Experimental study of bondslip performance of corroded reinforced concrete under cyclic loading,” Advances in Mechanical Engineering, vol. 7, no. 3, pp. 1–10, 2015. View at: Publisher Site  Google Scholar
 H. J. Zhou, J. L. Lu, and X. Xv, “Effects of stirrup corrosion on bondslip performance of reinforcing steel in concrete: An experimental study,” Construction Building Materials, vol. 93, pp. 257–266, 2015. View at: Publisher Site  Google Scholar
 H. J. Zhou and X. B. Liang, “Variation and degradation of steel and concrete bond performance with corroded stirrups,” Construction Building Materials, vol. 138, pp. 56–68, 2017. View at: Publisher Site  Google Scholar
 X. L. Zhang, Experimental study on degradation of basic mechanical properties of corroded reinforced concrete, Shenzhen University, 2016.
 J. B. Wang, Z. J. Qian, W. M. Qian et al., Probability and Statistics: Engineering Mathematics, Tongji University Press, 1994.
 L. G. Chen and C. Q. Fang, “Bond property of reinforced concrete with corroded reinforcement,” Industrial Construction, vol. 34, no. 5, pp. 15–17, 2004. View at: Google Scholar
 G. Xv, Study on Bond Performance of Corroded Reinforced Concrete, Huazhong University of Science Technology, 2007.
 L. Wang, Y. F. Ma, and J. R. Zhang, “Contrast experimental study on bond property of corroded reinforcement,” Joutnal of highway and transportation research and development, vol. 27, no. 6, pp. 91–96, 2010. View at: Google Scholar
 C. B. Bao, Experimental study on the bond of corroded reinforced concrete, Shandong University, 2015.
 J. P. Zhong, “Effect of rust corrosion on bond performance between steel bar and concrete,” Low Temperature Architecture Technology, vol. 34, no. 11, p. 6, 2012. View at: Google Scholar
 J. Wei, G. Xv, and Q. Wang, “Bond strength modeling for corroded reinforcing bar in concrete,” Journal of Building Structures, vol. 29, no. 12, pp. 123–126, 2008. View at: Google Scholar
 C. Fang, K. Lundgren, M. Plos, and K. Gylltoft, “Bond behaviour of corroded reinforcing steel bars in concrete,” Cement and Concrete Research, vol. 36, no. 10, pp. 1931–1938, 2006. View at: Publisher Site  Google Scholar
 Y. Zhao, H. Lin, K. Wu, and W. Jin, “Bond behaviour of normal/recycled concrete and corroded steel bars,” Construction and Building Materials, vol. 48, pp. 348–359, 2013. View at: Publisher Site  Google Scholar
 A. R. L. Kivell, Effects of bond deterioration due to corrosion on seismic performance of reinforced concrete structures, 2012.
 Y. S. Choi, S. T. Yi, and M. Y. Kim, “Effect of corrosion method of the reinforcing bar on bond characteristics in reinforced concrete specimens,” Construction Building Materials, vol. 54, no. 3, pp. 180–189, 2014. View at: Publisher Site  Google Scholar
 D. Y. Tan, Experimental study on bond behavior of corroded reinforced concrete, Chongqing University, 2012.
 X. Q. Xiao, Experimental study on bond behavior of corroded reinforced concrete, Central South University, 2011.
 H. Yalciner, O. Eren, and S. Sensoy, “An experimental study on the bond strength between reinforcement bars and concrete as a function of concrete cover, strength and corrosion level,” Cement and Concrete Research, vol. 42, no. 5, pp. 643–655, 2012. View at: Publisher Site  Google Scholar
 A. Kivell, A. Palermo, and A. Scott, “Complete model of corrosiondegraded cyclic bond performance in reinforced concrete,” Journal of Structural Engineering (United States), vol. 141, no. 9, Article ID 04014222, 2015. View at: Publisher Site  Google Scholar
 J. G. Cabrera, “Deterioration of concrete due to reinforcement steel corrosion,” Cement and Concrete Composites, vol. 18, no. 1, pp. 47–59, 1996. View at: Publisher Site  Google Scholar
 L. Chung, J.H. Jay Kim, and S.T. Yi, “Bond strength prediction for reinforced concrete members with highly corroded reinforcing bars,” Cement and Concrete Composites, vol. 30, no. 7, pp. 603–611, 2008. View at: Publisher Site  Google Scholar
 S. Coccia, S. Imperatore, and Z. Rinaldi, “Influence of corrosion on the bond strength of steel rebars in concrete,” Materials and Structures, vol. 49, no. 12, pp. 537–551, 2016. View at: Publisher Site  Google Scholar
 H.S. Lee, T. Noguchi, and F. Tomosawa, “Evaluation of the bond properties between concrete and reinforcement as a function of the degree of reinforcement corrosion,” Cement and Concrete Research, vol. 32, no. 8, pp. 1313–1318, 2002. View at: Publisher Site  Google Scholar
 Y. Zeng, Degradation of bond behavior of corroded reinforced concrete and its effect on bending stiffness of beams, Chongqing University, 2014.
 Q. C. Mo, Study on Bond and Slip Behavior of Corroded Reinforced Concrete and Ultrasonic Testing, Harbin Institute of Technology, 2016.
 X. Li, Experimental research on the effect of corroded deformed bars and concrete bonding properties, Yanshan University, 2013.
 H. W. Lin, Experimental study on bond behavior of corroded reinforced concrete under monotonic and repeated load, Zhejiang University, 2017.
 Y. Auyeung, P. Balaguru, and L. Chung, “Bond behavior of corroded reinforcement bars,” ACI Structural Journal, vol. 97, no. 2, pp. 214–221, 2000. View at: Google Scholar
 Y. Ma, Z. Guo, L. Wang, and J. Zhang, “Experimental investigation of corrosion effect on bond behavior between reinforcing bar and concrete,” Construction and Building Materials, vol. 152, pp. 240–249, 2017. View at: Publisher Site  Google Scholar
 H. Lin, Y. Zhao, J. Ožbolt, and R. HansWolf, “The bond behavior between concrete and corroded steel bar under repeated loading,” Engineering Structures, vol. 140, pp. 390–405, 2017. View at: Publisher Site  Google Scholar
 W. P. Zhang and Y. Zhang, “Experimental Study on the Degradation of Bonding Properties of Corroded Reinforced Bars and Concrete after Swelling,” Building Structure, vol. 1, pp. 31–33, 2002. View at: Google Scholar
 G. Xv, J. Wei, and Q. Wang, “Beam Test Study on Bond Behavior of Corroded Reinforcing Bar in Concrete,” Journal of Basic Science and Engineering, vol. 17, no. 4, pp. 549–557, 2009. View at: Google Scholar
 Y. L. Zhang, “Bond properties and Bearing capacity of corroded reinforced concrete member,” Xi'an University of Architecture Technology, 2011. View at: Google Scholar
 X.J. Hong and M. Zhao, “Loading velocity effects on bond performance between corroded bar and concrete,” Tongji Daxue Xuebao/Journal of Tongji University, vol. 30, no. 7, pp. 792–796, 2002. View at: Google Scholar
 D. W. Law, D. Tang, T. K. C. Molyneaux, and R. Gravina, “Impact of crack width on bond: Confined and unconfined rebar,” Materials and Structures/Materiaux et Constructions, vol. 44, no. 7, pp. 1287–1296, 2011. View at: Publisher Site  Google Scholar
 H. C. Wang, S. Q. He, and J. X. Hong, “Experimental studies on the bond character between corroded reinforcement and concrete subjected to freezethaw cycles,” Concrete, vol. 8, p. 1, 2007. View at: Google Scholar
 S. Q. He, Experimental Study on Durability of Reinforced Concrete Members in Chloride Environment, Dalian University of Technology, 2004.
 H. Lin and Y. Zhao, “Effects of confinements on the bond strength between concrete and corroded steel bars,” Construction and Building Materials, vol. 118, pp. 127–138, 2016. View at: Publisher Site  Google Scholar
 A. Shetty, K. Venkataramana, and K. S. B. Narayan, “Effect of corrosion on flexural bond strength,” Journal of Electrochemical Science Engineering, vol. 4, no. 3, 2014. View at: Google Scholar
 P. S. Mangat and M. S. Elgarf, “Bond characteristics of corroding reinforcement in concrete beams,” Materials and Structures/Materiaux et Constructions, vol. 32, no. 216, pp. 89–97, 1999. View at: Google Scholar
 M. M. Yang, Experimental study on the influence of the concrete cover thickness and steel bar position on the bond behaviors between corrosion steel bars and concrete, Dalian University of Technology, 2016.
 H. N. He, M. M. Yang, and J. X. Hong, “Influence of cover thickness on bond behaviors between concrete and slight corroded bars,” Journal of Water Resources and Architectural Engineering, vol. 14, no. 4, pp. 25–30, 2016 (Chinese). View at: Google Scholar
Copyright
Copyright © 2018 H. J. Zhou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.