Download or read book The Effect of Surface and Loading Conditions on the Corrosion Performance of Stainless Steel Rebar written by Kyle A. Anders and published by . This book was released on 2009 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deterioration of reinforced concrete structures due primarily to chloride induced corrosion of plain carbon-steel reinforcement is a widespread problem, particularly in areas close to marine environments and where de-icing salts are used to keep roadways clear of ice. Replacing plain carbon-steel rebar with highly corrosion resistant stainless steel rebar has been shown to greatly increase the lifespan of concrete structures in harsh environments, and yields favourable life-cycle costs despite high initial costs. In attempt to lower stainless steel rebar's initial cost of processing, this research compared its corrosion resistance in the pickled (mill scale removed) and as-rolled (mill scale intact) surface conditions. Rebar was embedded in highly-chloride contaminated concrete, and corrosion performance between the two surface types was compared in order to determine if conventional pickling of stainless steel rebar is necessary. A second part of this research addressed possible concern of reduced corrosion resistance of pickled stainless steel rebar in concrete exposed to chlorides when subjected to dynamic loading due to micro-motion at the concrete/crack interface. It was concluded that as-rolled stainless steel rebar in aggressive environments would provide sufficient corrosion resistance for the 75 year lifespan currently specified by the Canadian Bridge Code (CAN/CSA-S6-06, 2006), however it is recommended that monitoring of these specimens be continued to ensure high corrosion rates and/or concrete cracking do not develop. As well, investigation into the effects crevice corrosion cells found in typical concrete structures could have on as-rolled stainless steel rebar's corrosion resistance should be undertaken. With regard to loading conditions, no significant evidence was found suggesting that pickled stainless steel rebar has reduced corrosion resistance when loaded dynamically versus statically. Therefore pickled stainless steel rebar is recommended for use in dynamically loaded concrete structures if others factors permit. However, the higher electrochemical noise measured during cyclic loading suggests that corrosion behaviour could be influenced largely by frequency of loading, and so further study should be undertaken for applications involving more extreme cyclic loading conditions than those used in this experiment.

Download or read book Effects of Surface Condition on the Corrosion Performance of Stainless Steel Rebar written by Bradley P. Bergsma and published by . This book was released on 2009 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion of carbon (black) steel reinforcing bars (rebar) is the major cause of damage and deterioration of reinforced concrete structures in maritime regions and in climates where de-icing salts are used. The cause of the corrosion is diffusion of chloride ions to the steel surface through the concrete in which it is placed. The bars are naturally passivated by the high pH of concrete interstitial pore fluid, and will not corrode in chloride-free concrete. Chloride ions break down the passive film, allowing dissolution of the steel. Corrosion of reinforcing steel drastically reduces the service lives of concrete structures. Where chlorides can not be avoided, stainless steel is becoming increasingly popular as an alternative reinforcing material. Stainless steel is able to withstand greater concentrations of chlorides, extending the service lives of structure in which they are placed. Due to high initial cost, stainless steel is often avoided in the design of new structures. In order to reduce the cost of stainless rebar, it has been proposed that the standard process of abrasive blasting and pickling of the steels not be performed, as these steps are mainly used to restore a bright and shiny surface, a quality not required for steels embedded in concrete. AISI 304LN, AISI 316LN and 2205 duplex stainless steels were tested with pickled surfaces as well as with mill-scale intact (as-rolled) in order to determine the affect of pickling vs. not pickling on the corrosion behaviour of the steels. Steels were tested in solutions simulating concrete interstitial pore fluid containing from 0 to 16% Cl- by mass of solution, simulating cement paste with 0 to 7.5% Cl- by mass of cement, which is near the solubility limit of Cl- in pore fluid. Steels were also tested in thin mortar shells, with Cl- ions being rapidly diffused to the surface due to an applied potential gradient. The microcell corrosion performance of the as-rolled steels was slightly worse than that of pickled steels; however, the corrosion rates of the as-rolled steels at 16% Cl- in pore fluid are near 3 [mu]m/year, while black steel is normally observed to be actively corroding at 10 [mu]m/year in cement containing as low as 0.1% Cl- by mass of cement, or 0.2% Cl- by mass of solution. No significant difference was observed between different grades of stainless steel in either the as-rolled or pickled conditions. As-rolled stainless steels exhibited poor pitting resistance when an anodic potential is applied, but the corrosion occurs at potentials much higher than experienced in service and at Cl- concentrations far greater than that needed to initiate corrosion on black steel; the time required to reach these higher Cl- levels would allow for maintenance free service long enough to justify the cost of as-rolled stainless steel over black steel. The Canadian Highway Bridge Design Code, CSA S6-06, specifies that reinforced concrete bridges should meet a service life of 75 years. It is concluded that, given the time required for concentrated chlorides to accumulate at the steel, the stainless steel rebar in the as-rolled condition would allow reinforced concrete structures to reach the specified service life, as long as care is taken to avoid contamination of the steel/surface by black steel from handling, or by secondary phases within the steel, Cr23C6 and MnS in particular.

Download or read book Influence of Alloying Elements Testing Solution and Surface Roughness on Corrosion Behaviour of Stainless Steel Reinforcing Bars written by Ibrahim Ogunsanya and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The province of Ontario has moved from applying rock salt crystals, predominantly impure sodium chloride, to locally available anti-icing brine solutions with chloride amounts as high as 21%. At the same time, the specified design service life of highway structures has increased from 50 years to 75 years. The exposure to aggressive chloride brines has increased the need for more corrosion resistant reinforcing bar (rebar) than the traditional carbon steel rebar. However, the high cost of many stainless steel rebar alloys made them a last resort when concrete reinforcement options are considered. A major factor for their high cost is the price of their major alloying elements. Therefore, the contributions of these elements towards passive film properties, pitting corrosion resistance, critical chloride threshold (CCRIT) values and overall corrosion performance in the presence of deleterious species in concrete, such as chlorides, must be ascertained. This research aimed to provide a critical evaluation of the various parameters affecting long term corrosion performance of different grades of stainless steel rebar in concrete exposed to anti-icing brines. The first step to achieving this was to determine the variation in pore solution compositions of different concrete mixes so that bars can be tested in a similar environment. To do this, cement pastes of varying admixed chloride content, cementitious materials and water-to-cementitious ratio (w/cm) were cast and their pore solutions were analyzed for ionic composition and pH. The results revealed increasing dissolution of sulphate ions with increasing admixed chloride ions in the pore solution. These actual solutions were used in subsequent assessment procedures involving electrochemical techniques such as Mott-Schottky analysis, potentiostatic linear and non-linear polarization resistance and cyclic potentiodynamic polarization techniques. The goal was to determine the passive film properties, pitting characteristics, critical chloride threshold (CCRIT) and relative corrosion performance of carbon steel and five grades stainless steel rebar. Results showed the addition of sulphates to testing solutions suppressed the damage from chloride ions on steel passive films, by forming iron and nickel sulphides in passive films that provided additional protection. Results also showed that testing in lower pH solution, as done by many researchers, is conservative and underestimates corrosion resistance. The influence of the expensive stainless steel alloying elements (Cr, Ni, Mo, Mn) on the corrosion parameters listed above were then investigated. Chromium significantly improved these properties by decreasing passive film defects and increasing CCRIT values of the rebar. Molybdenum did not improve the corrosion resistance in the austenitic alloys but was beneficial in duplex alloys by concentrating in the ferritic component. Nickel was found to improve the outer layer of passive films properties by forming an Fe-Ni spinel, while manganese improved the inner passive layer. It is necessary for these observations in corrosion behaviour of rebar to be consistent. Consequently, other factors potentially leading to variations in corrosion performance of stainless steel rebar alloys were examined. These included the influence of variability in composition, microstructure and surface roughness between batches of stainless steel alloys from different manufacturers, and results showed surface roughness to be the major and overwhelming factor in corrosion resistance. The most important observation has been that, for the particular concrete mixture used in this research, the critical chloride threshold concentration, found by extrapolation of the experimental data, was greater than the solubility limit of chlorides in cement pores. This implies that chloride induced corrosion of the stainless alloys would not be possible in this concrete in the absence of cracks or major flaws.

Download or read book Proceedings of EcoComfort 2020 written by Zinoviy Blikharskyy and published by Springer Nature. This book was released on 2020-08-16 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the latest innovations and applications in the field of resource-saving technologies and advanced materials in civil and environmental engineering, as presented by leading international researchers and engineers at the 2nd International Scientific Conference EcoComfort and Current Issues of Civil Engineering, held in Lviv, Ukraine on September 16-18, 2020. It covers a diverse range of topics, including ecological and energy-saving technologies; renewable energy sources; heat, gas and water supply; microclimate provision systems; innovative building materials and products; smart technologies in water purification and treatment; protection of water ecosystems; and architectural shaping and structural solutions. The contributions, which were selected using a rigorous international peer-review process, highlight exciting ideas that will spur novel research directions and foster multidisciplinary collaborations.

Download or read book Corrosion of Steel in Concrete Structures written by Amir Poursaee and published by Woodhead Publishing. This book was released on 2023-02-20 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Essential reading for researchers, practitioners, and engineers, this book covers not only all the important aspects in the field of corrosion of steel reinforced concrete but also discusses new topics and future trends. Theoretical concepts of corrosion of steel in concrete structures, the variety of reinforcing materials and concrete, including stainless steel and galvanized steel, measurements and evaluations, such as electrochemical techniques and acoustic emission, protection and maintenance methods, and modelling, latest developments, and future trends in the field are discussed. Comprehensive coverage of the corrosion of steel bars in concrete, investigating the range of reinforcing materials, and types of concrete Introduces the latest measuring methods, data collection, and advanced modeling techniques Second edition covers a range of new, emerging topics such as the concept of chloride threshold value, concrete permeability and chloride diffusion, the role of steel microstructure, and innovations in corrosion detection devices

Download or read book The Case for Stainless Steel Reinforcing Bars written by Colin Bradley Van Niejenhuis and published by . This book was released on 2015 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Canada's ever expanding transportation network continues to age, the costs associated with rehabilitating and replacing structural elements, such as bridges, continues to grow. This rehabilitation is often required because the structural reinforcing has begun to corrode, producing corrosion product with a larger volume than the initial reinforcing steel, which leads to cracking and de-bonding of the concrete. In the past, most departments of transportation have used low cost, carbon steel. Now, as the Ministry of Transportation of Ontario looks for alternative materials with longer service lives, the use of stainless steel reinforcing bars in critical structural locations has become increasingly financially feasible. Thus, at the request of the Ministry of Transportation of Ontario, an experimental and analytical projected was undertaken to compare the corrosion resistance of six stainless steels and two corrosion resistant reinforcements: S31653, S32205, S32101, S30403, S24100, S32304, MMFX, and galvanized steel with that of the traditional low carbon 400W reinforcement. There are two objective of the project, first to experimentally compare the corrosion resistance of the different reinforcements in both sound and cracked concrete while being exposed to a 21.1% chloride brine, while the second is to create a model for the corrosion-limited service life of reinforced concrete, which includes both sound and cracked concrete. The experimental monitoring included comparing the corrosion resistance of the different reinforcements in: sound (non-cracked) concrete, concrete with a crack transverse to the reinforcement, and concrete with a longitudinal crack above, and parallel to, the reinforcement. After the concrete was cured for 28 days, the cracks were induced, and the sides that did not contain the cracks were coated with epoxy to ensure unidirectional chloride diffusion through the exposed area and the cracked region. The specimens were then monitored by conducting galvanostatic pulse (GP) tests weekly and linear polarization resistance (LPR) tests monthly. The resulting corrosion current density (icorr) and open circuit potentials (Ecorr) values were monitored over a 600 day exposure period. Both the icorr and Ecorr data indicate that the reinforcement in the sound concrete specimens remained passive over this period and, therefore, monitoring will continue until active corrosion initiates. In the longitudinal and transversely cracked concrete, the icorr and Ecorr values indicated that corrosion had initiated in a number of specimens, so all the specimens were removed from their chloride baths, autopsied, inspected, and ranked. The ranking of reinforcement from most resistant to least corrosion resistant is as follows: S32205, S32101, S32304, S30403, S31653, S24100, galvanized, MMFX, and 400W. The corrosion modelling expanded upon two models from the literature, Hartt et al. and Lu et al., by using Fick's second law to model the ingress of chloride in both sound and cracked concrete. Once the model was created, a Monte Carlo simulation was performed to statistically determine the effects of: crack width, crack density, concrete cover, chloride threshold concentration, surface chloride concentration, and chloride diffusion on the expected life of a concrete structure with both a 100 and 300 year service life. This allowed a critical cost ratio (CCR) to be computed, solely on the value of the reinforcement without taking into account any other owner or social costs. The CCR is defined as how much an owner would be willing to pay for corrosion resistant steel compared with 400W steel over the life of the structure. The results of this analysis can be summarized in three ways. First, this procedure has determined that the parameters that have the greatest effect on the service life of the structure from least to greatest are: surface chloride concentration, crack width and density, chloride diffusion rate of the concrete, and the chloride threshold level of the proposed alternative stainless steel. If the structural designer actively designs to limit the first three parameters, the financial feasibility of corrosion resistant reinforcing dramatically decreased. Second, 15 design curves have been created to help designers quickly assess the financial feasibility of corrosion resistant reinforcement based on the specific requirements of their highway structure. Third, if the design curves suggest corrosion resistant reinforcement is viable, it is recommended that the analysis be re-run for the proposed reinforcement once the chloride threshold for the specific corrosion resistant rebar grade and local surface chloride accumulations have been determined. This will allow the designers to have site specific critical cost ratios, allowing them to determine if the owner or societal costs must be included in the feasibility study. Both the experimental and modelling data strongly suggest that corrosion resistant steel, especially S32205 and S32101, are financially viable replacements for traditional 400W reinforcement, especially in critical structural applications where access or user delay costs prohibit frequent replacement or rehabilitation.

Download or read book Effects of Corrosion and Fatigue on the Load carrying Capacity of Structural and Reinforcing Steel written by Christopher Hahin and published by . This book was released on 1994 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Risk Based Technologies written by Prabhakar V. Varde and published by Springer. This book was released on 2018-12-10 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents selected topics in implementing a risk-based approach for complex engineering systems in general, and nuclear plants in particular. It addresses gap areas in implementing the risk-based approach to design, operation and regulation, covering materials reliability, digital system reliability, software reliability, human factor considerations, condition monitoring and prognosis, structural aspects in risk-based design as well as the application aspects like asset management for first-of-their-kind projects, strategic management and other academic aspect. Chapters are authored by renowned experts who address some of the identified challenges in implementation of risk-based approach in a clear and cogent manner, using illustrations, tables and photographs for ease of communication. This book will prove useful to researchers, professionals, and students alike.

Download or read book Effect of Accelerated Corrosion on the Bond Strength of Corrosion Resistant Reinforcing Bars Embedded in Concrete written by Sourav Khatua and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion of steel reinforcing bars embedded in concrete applications is a major problem all over the world. Effect of corrosion causes metal loss at sections, cracks in the concrete surrounding the reinforcing steel, spalling of cover concrete also leads to de-bonding of reinforcing bar from the concrete. Corrosion cracks in the surrounding concrete leads to loss in bond strength and finally reduce the structural strength and service life of the structure. This problem is consistently observed in structural slab bridges that are exposed to deicing salts during the winters. In the era of 1980's, black convention steel was replaced with epoxy-coated bars as a solution to prevent corrosion in bridge decks. However the advantage of using epoxy coated bars is still uncertain as the bond strength of these type of bars is a concern. Several researchers in the past have highlighted deleterious effect of corrosion on epoxy-coated bars that are damaged during handling. It is necessary to study the use of alternative reinforcing bars as means of corrosion protection in bridge deck applications. There are several corrosion resistant bars that are readily available in the market, but performance of these bars under accelerated corrosion conditions is still unclear. Six different types of bars which include, conventional black bars, epoxy-coated bars, hot dipped galvanizing bars, continuously galvanized bars, stainless steel bars and MMFX bars were studied in this thesis. The objective of this study is to investigate the effect of accelerated corrosion on bond strength of concrete. The bond between concrete and reinforcement bars play a major role in transfer of stresses from concrete to steel. However, corrosion weakens this bond, resulting in weakening of the Reinforced Concrete member. So, it was necessary to investigate the performance of CRR (Corrosion Resistant Bars) embedded in concrete and s ubjected to accelerated corrosion. The effect of addition of polypropylene fibers on the bond strength was studied. A total of 48 prism specimens were cast with CRR bars including the ones with fibers, of which 24 specimens were subjected to accelerated corrosion. The prisms were 6-inch cube with a reinforcing bar at the centre of each specimen. The embedment length of the bar was 2.5 inches at the mid-height of the section. An electrochemical cell was adopted by placing the specimens in a tank containing 5% salt solution with stainless steel cathode surrounding the specimen. The circuit was completed by connecting the cathode and the reinforcing bar to an external power supply. The specimens were subjected to accelerated corrosion for total of 21 days which includes a two-day wetting and one day drying cycle. Impressed current of 0.02A, calculated using Faraday's law to achieve 5% corrosion damage was supplied during the wetting cycle using external power source. The corroded specimens were then tested to investigate the loss of bond strength due to corrosion and capture any improvement in bond strength using polypropylene fibers. It was observed that, corrosion of bars showed serious bond loss leading to reduced pull-out strength with larger slip of the bars relative to the embedded concrete prisms. Addition of polypropylene fibers showed an improvement in the overall performance of the corroded specimens by increasing the load capacity, reducing slip and improving failure mode from brittle to more ductile mode, compared to un-corroded specimens..

Download or read book The Influence of Loading on the Corrosion of Steel in Cracked Ordinary Portland Cement and High Performance Concretes written by Shahzma Jafferali Jaffer and published by . This book was released on 2007 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes.

Download or read book Effect of Cathodic Protection on Epoxy coated Rebar written by S. Ray Taylor and published by . This book was released on 1998 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Epoxy coating is widely used to mitigate the access of chloride ions to the surface of a rebar. However, corrosion at the point of physical defects in the coating necessitates rehabilitation. Based on its effectiveness in mitigating corrosion of uncoated rebars, we examined cathodic protection (CP) as a method for rehabilitating epoxy-coated rebars (ECR). Although it is well established that cathodic polarization of epoxy coatings on steel in aqueous conditions leads to disbondment of the coating, neither the conditions that lead to this phenomenon nor the actual occurrence of this disbondment process has been determined for ECR in concrete. Since the integrity of the bond between the rebar and the concrete is essential to the composite strengthening by the rebar, the relationships among CP, the integrity of the epoxy coating, and the strength of the rebar/concrete bond must be investigated. The objectives of this study were (1) to determine if CP can effectively mitigate corrosion of coated rebar without adversely affecting the rebar/concrete interface, and (2) to examine the effect of cathodic polarization on the disbonding characteristics of the epoxy coating/rebar interface in concrete. Fifty-five samples of No. 5 ECR with coating defects were exposed to CP. Tensile loading produced splitting failures of all samples. This mode of failure allows greater sensitivity to the contributions of concrete/rebar adhesion and friction than do pullout failures. All electrochemical tests indicated that the cathodic polarization levels and times of application used in this study were effective in preventing corrosion of embedded ECR. An important finding was that the CP protection levels and times had no effect on the splitting failure characteristics based on comparisons of 95 percent confidence intervals. Multiple parameters within the electrochemical impedance spectra indicated that the epoxy coating was delaminating from the steel at the periphery of the defects. This phenomenon was verified in a post mortem analysis of the samples using scanning electron microscopy. The immediate significance of this result is that CP current demands could increase over time. Even though the levels of delamination in this study did not affect mechanical performance, a protective CP level that does not induce film delamination should be explored.

Download or read book Effect of Residual Stress and Surface Condition on the Stress Corrosion Cracking of Austenitic Stainless Steel written by Karen Naomi Shapiro and published by . This book was released on 2009 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Surface Finishing on Pitting Corrosion of Stainless Steel written by and published by . This book was released on 1999 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Pilot Experimental Study on the Low Cycle Fatigue Behavior of Stainless Steel Rebars for Earthquake Engineering Applications written by Yihui Zhou and published by . This book was released on 2008 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic application of stainless steel rebar (SSR) recently has attracted much attention in the civil engineering due to its superior material properties, including high corrosion resistance and high specific strength. However, as to all new materials, a number of shortcomings are unavoidable, such as high initial costs, unknown low-cycle fatigue behavior and uncertain ductility property. In this study, a series of tests on selected SSR were carried out. For the purpose of comparison, one type of traditional carbon steel (A706 G60) rebar and a new material (MMFX II) were also tested. A706 G60 has been promoted in the recent design specification of reinforced concrete, particularly in the seismic design. MMFX II is high strength steel appeared in the market recently. The specific objective of this study is to investigate the low-cycle fatigue and ductility properties of the selected SSR. The test specimens, both for the low fatigue and the monotonic loading conditions, were designed according to the ASTM specifications and fabricated from #8 rebars. The tests were strain controlled. An electronic hydraulic loading system manufactured by MTS at the Structural Engineering & Earthquake Simulation Laboratory (SEESL) at the University at Buffalo was used, and MTS displacement extensometers were used to measure the elongations. For the low-cycle fatigue tests, specimens were subjected to constant amplitude strain of various magnitudes. Strain based strain-life formulae were obtained by regression analysis of the experimental results. Compared to results of the traditional carbon steel rebar, SSR has shown higher ductility and longer fatigue life.

Download or read book Stainless Steel in Concrete written by European Federation of Corrosion and published by Woodhead Publishing Limited. This book was released on 1996 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book fib Model Code for Concrete Structures 2010 written by fib - federation internationale du beton and published by John Wiley & Sons. This book was released on 2013-12-04 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Federation for Structural Concrete (fib) is a pre-normative organization. 'Pre-normative' implies pioneering work in codification. This work has now been realized with the fib Model Code 2010. The objectives of the fib Model Code 2010 are to serve as a basis for future codes for concrete structures, and present new developments with regard to concrete structures, structural materials and new ideas in order to achieve optimum behaviour. The fib Model Code 2010 is now the most comprehensive code on concrete structures, including their complete life cycle: conceptual design, dimensioning, construction, conservation and dismantlement. It is expected to become an important document for both national and international code committees, practitioners and researchers. The fib Model Code 2010 was produced during the last ten years through an exceptional effort by Joost Walraven (Convener; Delft University of Technology, The Netherlands), Agnieszka Bigaj-van Vliet (Technical Secretary; TNO Built Environment and Geosciences, The Netherlands) as well as experts out of 44 countries from five continents.

Download or read book High performance concrete pavements written by and published by . This book was released on 2002 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: