O.H. Adejo, D.V. Abere, S.A. Ojo , F.U. Uzuh and O.M. Ogunronbi
Keywords: steel, bars, corrosion, degradation, concrete, atmosphere, unexposed, expose
Abstract:
Reinforcement steel bars are often exposed to the atmosphere before use in concrete
structures. This exposure results in corrosion of these reinforcement bars. Corrosion of
reinforcement bars is a common form of degradation of reinforced concrete structures. The
electrochemical attack affects the mechanical properties of steel rebars. This study analysed
the effect of exposure to rainfall on the mechanical and corrosion properties of reinforcing
steel bars. The bars were divided into two; one part was exposed to the atmosphere for a
period of four months during the rainy season while the other was unexposed. Afterwards;
mechanical, corrosion and metallographic tests were carried out on the steel samples. The
results obtained showed that the hardness, impact strength and ductility increased with
exposure while the yield and tensile strengths decreased with exposure. The exposed bar had
higher corrosion rates than the unexposed bar in 1M hydrochloric acid (HCl) while in 1M
sodium chloride (NaCl), the corrosion rates for both the exposed and unexposed bars did not
follow a particular trend
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ISSN 1466-8858 Volume 22, Preprint 53 first submitted 23 September 2019 Investigation of the Effect of exposing reinforcement steel bars to Atmosphere O.H. Adejo1, D.V. Abere1*, S.A. Ojo2, F.U. Uzuh1, O.M. Ogunronbi1 1 National Metallurgical Development Centre, Jos Nigeria Department of Mechanical Engineering, University of Akron, Ohio USA 2 *Corresponding Author: aberevictor@gmail.com Abstract Reinforcement steel bars are often exposed to the atmosphere before use in concrete structures. This exposure results in corrosion of these reinforcement bars. Corrosion of reinforcement bars is a common form of degradation of reinforced concrete structures. The electrochemical attack affects the mechanical properties of steel rebars. This study analysed the effect of exposure to rainfall on the mechanical and corrosion properties of reinforcing steel bars. The bars were divided into two; one part was exposed to the atmosphere for a period of four months during the rainy season while the other was unexposed. Afterwards; mechanical, corrosion and metallographic tests were carried out on the steel samples. The results obtained showed that the hardness, impact strength and ductility increased with exposure while the yield and tensile strengths decreased with exposure. The exposed bar had higher corrosion rates than the unexposed bar in 1M hydrochloric acid (HCl) while in 1M sodium chloride (NaCl), the corrosion rates for both the exposed and unexposed bars did not follow a particular trend. Keywords: steel, bars, corrosion, degradation, concrete, atmosphere, unexposed, expose 1.0 Introduction concrete in compression; it is usually Reinforcement steel is a common steel bar, formed from carbon steel and is given and is commonly used as a tensioning ridges for better mechanical anchoring to device the concrete. The problem of durability of in reinforced concrete and reinforced masonry structures holding the the reinforced concrete has arisen, © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 in the last decades. Volume first submitted 23 September dramatically, The 22, Preprint these 53environments react with the2019 analysis of in reinforcement steels determines how long has and how well the structures will perform in shown that one of the most dangerous service. ASTM terminology (G15) defines degradation phenomenon is connected to corrosion the corrosion of the reinforcing steel bars electrochemical (Carino, (1999). One approach that can be material, followed to obtain durable reinforced environment that produces a deterioration concrete structures is to improve the of the material and its properties (Song and durability of reinforcing steel. Exposure to Saraswathy, 2007). Corrosion damages the rainfall steels superficial layer of steel rebar’s, causing a The worsening of their mechanical properties reinforced the actual concrete affects gradually and damages constructions reinforcement detrimentally. the reaction usually a between metal, its Corrosion enhances damage and creates degrade. Steel, a major source of structural pits and notches, resulting in stress strength concentration of microstructural imbalance (So and Millard, 2007). points and a and water causes reinforcing steels to because strength and or in easily of chemical combination of ultra violet light, oxygen corrodes terms as and ductility. progressive reduction of strength (Carino, 1999). Repairing damage caused by corrosion is a Corrosion is a natural phenomenon man multibillion dollar problem. Observations has to live with, it cannot be totally of numerous structures show that corrosion eliminated. The best that could be done is of reinforcing steels is either a prime factor to adapt methods to minimize its effects. or at least an important factor, contributing Reinforcement steel bars are usually to staining, cracking and/or spalling of exposed corrosive concrete structures (Bjegovic et al., 2000). environment or the other. The manner A tour of construction sites show that to one form of © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858steel bars are left exposed Volume reinforcing to 22, Preprint Avery53 first submitted Izod impact23 September machine,2019 the elements for long periods of time 120FT.Lb.capacities (Roberge, 1999). The extent and effect of Birmigham England, 500KN Capacity degradation due to such exposure has not Denison Tensometer, model T4282, Leeds been adequately investigated. The aim of England this study therefore, is to investigate the (Manually/Electrically effect of this exposure to the mechanical Polishing and corrosion properties of the reinforcing Microscope with In-built Camera, retort steel bars. stand, beakers, hack saw, tongs, grit papers Grinding Machine, type 6701 Machine controlled), Metallurgical (sizes 120, 180, 320, 400, 600) and flat 2.0 Materials and method file. 2.1 Material The steel material used is a 10mm Experimental Procedure diameter reinforcing steel bar which was Sample Preparation sourced locally. The chemical analysis of the material was carried out at National The steel sample was cut into two (2), one Metallurgical Development Centre, Jos was exposed to the atmosphere during the using an Optical Emission Spectrometer. rainy season for four months while the Other materials used include hydrochloric other was kept in a dry place. The samples acid (HCl), sodium hydroxide (NaOH), were then cut into the required dimension sodium chloride (NaCl), water Nital of 10mmx10mm for the corrosion test with (etchant), diamond polish, alumina. The the use of hack saw. The samples were equipment used in the course of this placed on a vice before cutting. During research include digital weighing balance, cutting, coolant (water) was used to cool Indentec off the sample from heat generated as this Universal Machine model Hardness Testing 8187.5 LKV, W & T © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN Volume 22, Preprint 53 of 1M firstNaCl submitted 23remaining Septembersix2019 can1466-8858 affect its properties/microstructure. solution and the About 18 samples were cut from each rod. i. Tensile samples – about 200mm was cut from the sample for tensile tests. An average of 2 samples was NaOH by means of threads. The above procedure was repeated for the unexposed steel bars using the remaining solutions of 1M HCl, 1M NaCl and 1M NaOH. A cut from both rod samples. ii. (6) were suspended in the solution of 1M Impact samples – about 200mm was cut from the sample for impact sample of each rod (i.e. the exposed and unexposed) was removed from each of the solutions (i.e. 1M HCl, 1M NaOH and 1M testing. A total of 42 samples were prepared for the various tests NaCl) after every five (5) days and weighed. The weight was then recorded as the final weight of the coupons. The conducted. corrosion test was carried out for a total of Corrosion test thirty (30) days. The prepared samples were first weighed Mechanical Test using the analytical weighing balance and the readings recorded as the initial weight Tensile Test of the coupons. The beakers were washed The tensile test was carried out using a and cloth. 500KN capacity Dension Tensometer. The Concentrations of 1M HCl, 1M NaCl and actual load used for the test was set at 1M NaOH were prepared and poured into 200KN. The specimens for testing were three (3) beakers each. Six (6) samples of marked with a gauge length of 50mm with the exposed steel bar were suspended in the help of marking sectional area was the solution of 1M HCl, six other samples measured for each sample before testing. of the exposed bar were suspended in the Each of the samples attached the dial cleaned using a smooth © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 Volume 53 the sample. first submitted 23 September gauge (extensometer), which measures the 22, Preprint holding The chuck holding the2019 strain as the tensile load is applied while pendulum was released as the potential the other side of the Tensometer measures energy was converted to kinetic energy, the force applied to the samples. In the until it struck the sample. The energy process of testing, continuous load was possessed by the pendulum rose on the applied to the sample at an interval of 5KN other side of the machine to a height lower until it fractured. The yield load, maximum than its initial height on the opposite side load and the breaking load with their of the impact testing machine. The energy corresponding extensions were read. consumed in breaking the specimen was Impact Test read from the dial of the impact testing machine. The energy was measured in foo- The impact test was performed using the pounds and it is known as the notched W & T Avery Impact Testing machine. impact strength. The samples for impact test were noticed at the centre with the use of a v-shaped (Note: 1 foot-pound = 1.35581795 Joules) file. The diameters of the samples were Metallography measured using a Vernier calliper. This Sample Preparation was followed by filling to get the v-notch shape on the sample. The dimensions of the test specimen were 80mm length, 10mm diameter and 2mm depth of the notch at the middle. The notched samples were placed inside a vice in the Izod machine, the v-notch side facing the pendulum. The pendulum was raised to a standard height, with reference to the vise The samples were sectioned to suitable sizes that could be handled. The samples were then filed to obtain flat surfaces on both sides of the samples in order to enhance accurate viewing under the microscope, easy and faster results during grinding, and also for accuracy the hardness test. Water was used as coolant. Grinding © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 53the chemical first submitted Both rough and fine grinding wereVolume carried 22, Preprint This is attack 23 of September the exposed2019 out on the specimen. The rough grinding sample surface. The etchant used was 2% was done using the electrically operated nital. Etching of the steel samples was grinding machine and grit paper (silicon dome b swabbing, using cotton wool until carbide) of grit size 120. Fine grinding was the surface was properly etched. done using the manually operated grinding Metallographic Examination machine and silicon carbide papers of grit The etched samples were viewed under the sizes 180, 320, 400 and 600 till smooth, metallurgical microscope to see the scratch-less or mirror-like surface was different phases present. Photomicrographs obtained. Water was added as coolant were obtained by taking digital photograph during grinding. of the microstructure revealed by the Polishing It was done by mechanical polishing, which is a gradual removal of materials etching. Soft copies of the images were saved for easy printing. Hardness Test from the sample surfaces. The samples The samples used for the micrograph were went through two stages of polishing; fine further ground using the 600 grit paper to and rough polishing. Rough polishing was remove the etched surface from the done with cloth impregnated with 6 to 9µ samples. The ground samples were each particle diamond paste and then followed placed on the anvil and were raised up by 3µ particle size alumina on a spot against an indenter until a minor load was polishing cloth. Polishing was done to reached. The major load was applied on obtain a mirror-like surface. the indenter by a lever, enough time Etching passing for the indenter to press into the test sample and stop. © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 Results and Discussion Volume 22, Preprint 53 obtained first submitted 23 work September The results from this are 2019 presented below Table 1: Chemical Analysis of Reinforcing Steel sample Element Content % C 0.27 Si 0.15 Mn 0.80 P 0.040 S 0.050 Cr 0.07 Ni 0.30 Mo 0.30 Al 0.00 Cu 0.30 Ti 0.00 Fe 97.99 Corrosion Test Results The results from the corrosion test are shown in figures 1, 2 and 3 Figure 1: Variation of Corrosion Rate with Exposure Time in a solution of 1M HCl at Room Temperature. © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 Volume 22, Preprint 53 first submitted 23 September 2019 Figure 2: Variation of Corrosion Rate with Exposure Time in a solution of 1M NaOH at Room Temperature. Figure 3: Variation of Corrosion Rate with Exposure Time in a solution of 1M NaCl at Room Temperature. Hardness Test Results Table 2 – Results of Hardness test of Unexposed and Exposed Steel Bars S/N 1 2 TREATMMENTS Unexposed Exposed HARDNESS (HRA) 55.2 57.1 © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSNImpact 1466-8858 Test Results Volume 22, Preprint 53 first submitted 23 September 2019 Table 3 – Results of Impact test of Unexposed and Exposed Steel Bars S/N TREATMMENTS IMPACT (JOULES) 1 Unexposed 63.7 2 Exposed 67.8 Tensile Test Results Table 4 – Results of Tensile test of Unexposed and Exposed Steel Bars S/N TREATMMENTS 1 2 Unexposed Exposed PERCENTAGE REDUCTION IN AREA (%) 45.25 64.00 PERCENTAGE ELONGATION (%) 11.0 12.5 YIELD STRENGTH (MPa) 372.0 361.6 TENSILE STRENGTH (MPa) 687.5 578.0 Metallographic Examination Figures 4 and 5 show the micrographs of the test samples under investigation Figure 4. Micrograph of As-Received Reinforcement Bar. The Microstructure Consists of Uniform Distribution of pearlite (dark patches) and Ferrite (white patches). (x200) © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 Volume 22, Preprint 53 first submitted 23 September 2019 Figure 5: Micrograph of Exposed Reinforcement Bar. The Microstructure Consists of Uniform Distribution of pearlite (dark patches) and Ferrite (white patches). (x200) Discussion of Results be as a result of the formation of Corrosion corrosion-accelerating scale or the removal Corrosion rate of the steel sample in HCl of the resistant surface layer of metal increases with increase in exposure time. (Ahmad, 2003). The gradual decrease in HCl is very corrosive to most metals and corrosion rate could be as a result of alloys or depletion of a corrosive environment or oxidizing agents are present (Fontana, removal of less resistant surface layer of 2005). From figure 1, it could be observed the that the corrosion rate of the exposed bar deposition of an impervious metal oxide was higher than that of the unexposed bar film, which is a solid interfacial compound in a solution of 1M HCl. For both bars, the that protects the metal against further corrosion rate initially increased for the oxidation could be another reason (Carino, first ten days of exposure and gradually 1999). The higher corrosion rate of the decreased with increasing exposure time. exposed bar could be as a result of a The initial increase in corrosion rate could decrease in its corrosion resistance by the especially when aeration metal (Fontana, 2005). Also, © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858corrosion it had been subjected Volume 22, Preprint 53 during first submitted September atmosphere increased the next 23 five days and2019 to (Verma et al., 2013). gradually decreased during the remaining NaOH is not particularly corrosive and can be handled in steel in most applications where contamination is not a problem (Fontana, 2005). From figure 2, the corrosion rate for both steel bars was the same in a solution of 1M NaOH. This is because NaOH is particularly corrosive to steels (Bjegovic et al., 2000). The corrosion rates for both bars decreased with increasing exposure time. Chloride solution is highly corrosive. It is a good electrolyte and can cause galvanic corrosion and crevice corrosion. Corrosion in seawater is affected by oxygen content (Fontana, 2005). Seawater also causes pitting corrosion in stagnant condition (Roberge, 1999). Corrosion rates of metals in seawater increases with increasing exposure time (Roberge, 1999). From figure 3, the corrosion rate of the exposed bar in 1M NaCl decreased during the first ten days of exposure, it became steady for the next five days of exposure, suddenly period of exposure the initial decrease in corrosion rate could be as a result of the deposition of an impervious metal oxide film, which is a solid interfacial oxide compound that protects the metal against further oxidation (Hussain and Ishida, 2012). The rapid increase in corrosion rate with increasing exposure time could have been as a result of breakdown of the oxide film leaving localized bare metal experiencing corrosion at relatively high potential due to instability of the passivation or the presence of environment impurities that retard the formation of the passive film or accelerates its degradation (Burstein, 1994). The final decrease healing nature of the film that, when broken, will repair itself on re-exposure to oxidizing condition (Khanna, 1999). The corrosion rate of the unexposed steel bar decreased initially, increased after the first ten days of exposure, became steady for some time, decreased again and finally © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 Volume 53 is first submitted 23 September increased. The initial decrease could have 22, Preprint present 67.9% and the amount of2019 been as a result of the deposition of an pearlite is 32.1%. From these results, it is impervious metal oxide film, the increase expected that the microstructure of the in corrosion rate could have been as a steel should have a uniform distribution of result of the breakdown of the oxide film, ferrite the decrease in corrosion rate with time amounts. Therefore, from the micrographs, again could have been as a result of the re- it can be seen that the microstructures do deposition of the oxide film and the final not deviate from the expected outcome (So increase in corrosion rate with exposure and Millard, 2007). time would have been as a result of the and pearlite in nearly equal Hardness breakdown of the oxide film (Song and From Table 2, the unexposed bar hardness Saraswathy, 2007). value is 55.2 HRA while the exposed bar Metallography hardness value is 57.1 HRA. This implies Upon inspection of the micrographs for the that the exposed bar is slightly more exposed and unexposed steel bars, no resistant to penetration than the exposed variation was bar. This could have been as a result of both some chemical reactions that occurred showed a uniform distribution of pearlite during the exposure and formation of rusts (dark patches) and ferrite (white patches). that increased the surface strength of the The lack of variation in the microstructures exposed of the steel rods could be as a result of the Bhattacharjee, 2009). observed. in the The microstructure microstructures steel bar (Pradhan and exposed period not being long enough to Impact have much effect on the microstructure of the exposed steel bar. Using the lever rule, the amount of ferrite that is expected to be From Table 3, the unexposed steel bar had an impact value of 63.7 Joules while the exposed bar had an impact value of 67.8 © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 Volume first submitted 23observed September Joules. This implies that the exposed bar 22, Preprint From 53 these results, it can be that2019 has a toughness higher than that of the the exposed bars had lower yield and unexposed bar. This is as a result of the tensile exposed bar having lower yield strength unexposed bars. This implies that the and fatigue strength. Toughness usually exposed bars required less loads to cause increases with reduction in yielding and deformation than the unexposed bars fatigue strengths (Cairns and Melville, (Cairns and 2003). because of the atmospheric corrosion they Tensile From table 4, it can be seen that the unexposed steel bar had a percentage reduction in area of 45.25% and a percentage elongation of 11.0% while the exposed bar had a percentage reduction in area of 64.0% and a percentage elongation strengths compared with the Melville, 2003). This is had been subjected to which caused a deterioration of their yield and tensile strengths. Corrosion damages reinforcement bars causing a worsening of their tensile and yield strengths and the tensile property of steel is its most attractive property for use in concrete of 12.5%. From these results, it can be structure (Ahmad S. (2003). seen that the exposed bars are more ductile Conclusion than the unexposed bars. This could have Based on the research carried out on the been as a result of the formation of rust effect of exposure to rainfall on the due to the exposure in the exposed bars. mechanical and corrosion properties of From Table 4 also, the unexposed steel 10mm diameter reinforcing steel rods, the bars had yield strength of 327 MPa and a following conclusions were drawn: tensile strength of 687.5 MPa while the exposed bar had a yield strength of 361.6 MPa and a tensile strength of 578 MPa. © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN Volume 22, Preprint first submitted I 1466-8858 The hardness value of the exposed VI 53The corrosion rate 23 of September the exposed2019 bar was higher than that of the unexposed bar was relatively higher than that of the bar. unexposed II The impact value of the exposed bar was higher than that of the unexposed. bar in a solution of 1M HCl. The corrosion increased and then decreased with exposure time. In a solution of 1M NaOH, the corrosion rates III The exposed bar had higher values for both bars were the same. In the of percentage reduction in area and solution of 1M NaCl, the corrosion rates percentage elongation. The elongation for both the exposed and values of the unexposed steel unexposed rod bars did not follow a particular trend. conformed to the standard specified for Grade 420 steels by the Standard Therefore, based on the outcome of this study, it can be inferred that exposure of Organisation of Nigeria. reinforcing bars to the atmosphere during IV The exposed bars had poorer yield rainy season leads to the deterioration of and tensile strengths than the unexposed tensile and corrosion resistant properties of bars. The yield strength of the these steel bars to some extent and as a unexposed bar does not conform to the result may lead to failure of steel standard set by the Standard reinforced concrete structures. Therefore, Organisation of Nigeria. reinforcement bars should not be exposed V No variation was seen in the to the atmosphere during the rainy season microstructures of both the exposed and before use as reinforcement for concrete unexposed steel structures. rods. The microstructures obtained conformed to the References microstructures expected using lever rule. the Ahmad S. (2003) “Reinforcement corrosion in concrete structures, its monitoring and service life © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work. ISSN 1466-8858 53 O.P. first submitted 23Science September prediction—a review,” CementVolume and 22, Preprint Khanna, (1999). “Material and 2019 Concrete Composites, vol. 25, no. 4-5, pp. 459–471. Bjegovic D., Mikulic D., and Sekulic D. 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Pradhan B. and Bhattacharjee B. (2009) “Half-cell potential as an indicator of chloride-induced rebar corrosion initiation in RC,” Journal of Materials in Civil Engineering, vol. 21, no. 10, pp. 543–552. Roberge, P.R. (1999). “Handbook of Corrosion Engineering” McGraw Hill, New York, pp. 1-5, 13-16, 129-186. So H. and Millard S. G. (2007), “Assessment of corrosion rate of reinforcing steel in concrete using Galvanostatic pulse transient technique,” International Journal of Computing Science and Mathematics, vol. 1, no. 1, pp. 83–88. Song H. and Saraswathy V.(2007) “Corrosion monitoring of reinforced concrete structures—a review,” International Journal of Electrochemical Science, vol. 2, pp. 1–28, 2007. Verma S. K., Bhadauria S. S., and Akhtar S. (2013) “Review of non destructive testing methods for condition monitoring of concrete structures,” Journal of Construction Engineering, vol. 2013, Article ID 834572, 11. © 2019 University of Manchester and the authors. This is a preprint of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers' comments, be published online at http://www.jcse.org in due course. Until it has been fully published it should not normally be referenced in published work.