Dissertations / Theses on the topic 'Chloride induced corrosion'
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1
McCarthy, Michael John. "Chloride and carbonation-induced reinforcement corrosion in PFA concrete." Thesis, University of Dundee, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490143.
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Govindarajan, Balakumaran Soundar Sriram. "Corrosion Testing and Modeling of Chloride-Induced Corrosion Deterioration of Concrete Bridge Decks." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26437.
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Modeling of chloride-induced deterioration of bridge decks by using Fickâ s Second Law of diffusion was performed. The objective of this study is to select suitable input parameters for the model to estimate the service life of bridge decks. Five bridge decks, one in each of the following states, Virginia, Florida, New Jersey, New York, and Minnesota were evaluated.
Data collection process involved visual inspections, damage surveys, corrosion testing including continuity, one-point resistivity, four-point resistivity, half-cell potentials, and three-electrode linear polarization, reinforcement cover depths, chloride samples. The Virginia bridge deck was built with epoxy-coated reinforcement as top reinforcement mat and black bar as the bottom mat. The Florida bridge is a segmental prestressed box girder structure built with black bar. The New Jersey bridge deck was overlaid with latex modified concrete. The New York bridge deck, which was built in 1990, is six inch concrete topping over prestressed adjacent box beams structure with epoxy-coated bar in the negative moment area. The Minnesota bridge was rebuilt in 1984. The deck was rebuilt with epoxy coated reinforcing steel in the top and bottom mats.
The probabilistic Fickian model requires reinforcement cover depths, surface chloride concentration, chloride initiation concentration, and diffusion coefficients as input parameters. The chloride initiation concentration was input via parametric bootstrapping, while the other parameters were input as simple bootstrapping. Chloride initiation concentration was determined from the chloride concentration at the reinforcement bar depths.
The modeling results showed that the deterioration of the Virginia bridge deck was corrosion controlled and the bridge will undergo increasingly severe damage in the future. Florida bridge deck is not undergoing corrosion and will not experience corrosion damage within 100 years. New Jersey bridge deckâ s service life has been most likely extended by the overlay. Deterioration of the New York bridge was not corrosion controlled, but was related to longitudinal cracking of the topping at match lines of adjacent box beams. Minnesota bridge deck is delaminated and contained a large number of cracks that should be included in service life modeling; otherwise the service life estimate is underestimated.
In addition to service life corrosion performance modeling, analyses were conducted on the relationships and interrelations of resistivity, corrosion potential, corrosion current and chloride at the reinforcing bar depth.Ph. D.
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Siegwart, Michael. "The feasibility of electrochemical chloride extraction on prestressed concrete structures." Thesis, University of Ulster, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252423.
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Angst, Ueli. "Chloride induced reinforcement corrosion in concrete : Concept of critical chloride content – methods and mechanisms." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14245.
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Chloride induced reinforcement corrosion is widely accepted to be the most frequent mechanism causing premature degradation of reinforced concrete structures. Condition assessment and service life prediction is based on comparing the chloride content in the concrete at the steel depth – either measured in the field or computed by means of theoretical modelling – with the chloride content that is believed to be tolerable before corrosion starts. The latter is commonly referred to as critical chloride content or chloride threshold value. Owing to the considerable statistical variation of the parameters involved in service life considerations, probabilistic approaches are preferentially used since these aim at taking into account the uncertainties inherent to all parameters – at least on a theoretical basis. The present thesis approached the issue of chloride induced reinforcement corrosion from various angles. First, a non-destructive chloride measurement technique was studied. Second, the critical chloride content was reviewed with particular focus on how to determine this value experimentally and on common practice of its application. In a third part, the mechanism of chloride induced corrosion was experimentally studied. Regarding the measurement of chlorides, the application of ion selective electrodes (ISEs) as non-destructive chloride sensors in concrete was investigated. It was found that silver / silver chloride electrodes respond to the chloride ion activity in the pore solution as expected from theory and are functional also in highly alkaline environments. However, correct measurement of the sensor potential is the critical step and in this regard, the presence of diffusion potentials was identified as serious error source. These disturbing potentials arise from concentration gradients along the measurement path between reference electrode and ISE, particularly owing to pH gradients and chloride profiles. The error can be minimised by optimal placing of the reference electrode with respect to the ISE. Generally, in uncarbonated, alkaline concrete, the accuracy of this non-destructive chloride measurement method was found to be comparable to the accuracy of common procedures to determine the acid-soluble chloride content in concrete powder. On the other hand, when the pH of the concrete is on a lower level such as owing to the presence of pozzolanas, the adverse effect of diffusion potentials arising from chloride profiles increases and negatively affects the measurement accuracy. A review on the critical chloride content has shown that this parameter scatters significantly in the literature and that the published data does not offer a basis to improve service life predictions. The reported values are not consistent, particularly regarding non-traditional binder types. This was, at least partly, explained by the wide variety of experimental methods and the pronounced effect of certain experimental parameters. It was concluded that there is a strong need for a generally accepted, practice-related test setup for the critical chloride content. Without reliable input data, the common practice of probabilistic service life modelling is highly questionable. Both based on experimental results as well as the literature review, recommendations were made for a realistic test setup; these include the use of ribbed steel in as-received condition, chloride exposure by cyclic wetting and drying as well as leaving the rebar at its free corrosion potential rather than subjecting it to potentiostatic control. While it was from experimental work concluded that even in rather small laboratory specimens, the cathode is sufficiently large to provide realistic conditions for (early) pitting corrosion, probabilistic considerations have illustrated that the specimen size is likely to significantly influence the measured critical chloride content. More specifically, the smaller the specimens, the higher the expected mean critical chloride content and the larger the scatter of measured values. It was further discussed how the size effect influences the concept of critical chloride content and service life modelling in general. It was suggested that the size of specimens on which the critical chloride content is measured has to be taken into account when transferring the values to structures of real-life dimensions in probabilistic service life calculations. A procedure of how this can be done by considering structural behaviour was sketched (characteristic length). Regarding corrosion performance, the steel/concrete interface was found to be the most important influencing factor. Investigations by means of scanning electron microscopy revealed microstructural differences of top and lower sides of rebars that were horizontally orientated during casting, in particular the presence of a bleed-water zone below the reinforcement. It was striking that chloride induced corrosion initiated preferentially on the rebar side with the bleed-water zone regardless of the direction of chloride ingress. Also entrapped air voids were frequently observed at the steel/concrete interface; however, these coincided never with the location of corrosion onset. It was suggested that the internal moisture state is decisive in determining which interfacial defects present a risk of corrosion initiation. Last but not least, it was experimentally observed that steel embedded in concrete might depassivate/repassivate several times until stable pitting corrosion is achieved – at least under unpolarised conditions. After the first signs of corrosion onset, a marked increase in chloride content was often required to prevent repassivation and to enable stable pit growth. The time at which the chloride content is measured and taken as critical chloride content is thus decisive for the outcome of a laboratory test method. It was suggested that in order to obtain practicerelated chloride threshold values, this should be done as soon as stable pit growth is achieved (rather than at the first depassivation event). Finally, measurements after depassivation provided insight into the mechanism of early pitting corrosion and lead to the conclusion that the corrosion kinetics are at this stage dominated by anodic diffusion control.
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Cao, Ji. "Prediction and optimization of chloride-induced corrosion of concrete structures /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1456291171&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Zarouni, Ismael. "Effects of admixtures on chloride-induced corrosion of steel in concrete." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438568.
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Yonezawa, T. "Pore sollution composition and chloride-induced corrosion of steel in concrete." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383941.
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Al-Khyatt, Ala'a Ismael Mohammed. "High temperature chloride induced corrosion of nickle and nickle based alloys." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305267.
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Scatigno, Giuseppe Giovanni. "Chloride-induced transgranular stress corrosion cracking of austenitic stainless steel 304L." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/51506.
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Stress corrosion cracking (SCC) of austenitic stainless steels has been a known failure mode for more than 80 years and it continues to be a major cause of concern in the nuclear industry. The so-called nuclear grades, such as 304L, contain low levels of C and are therefore hard to sensitise, which is a major problem with high C grades, and these low C grades mainly fail by transgranular SCC. The effect of cold work (CW) has long been known to have a detrimental effect on SCC performance of a stainless steel component. CW is readily introduced in engineering components, through manufacturing history, or implementation, i.e. welding and hammering during fitting. The aim of this thesis is to systematically assess the role of CW in Cl-induced atmospheric SCC in 304L grade austenitic stainless steel. 304L is widely used in the nuclear industry, for both the primary cooling system of nuclear power plants and dry casks for interim storage of spent nuclear fuel. CW was applied in uniaxial tension to levels of 0, 0.5, 1, 2, 5 10, 20, and 40%. The specimens were loaded in a jig to produce a uniform stress of 60 MPa on the top surface and corroded under atmospheric conditions at 75°C, 70% relative humidity, using MgCl2, for 20 days. The role of applied stress (from 60-180 MPa), on SCC susceptibility was investigated at a fixed level of CW (chosen as 10% CW after preliminary experiments) using indicators such as crack density. Secondary and transmission electron microscopy, electron back-scattered diffraction, focused ion beam and secondary ion spectroscopy were the main characterisation techniques used. The maximum susceptibility to SCC was observed between 0.5-5% CW, while 20 and 40% CW did not exhibit cracking. The characterisation of the samples tested provided evidence that Cl is found ahead of the crack tip, whereas oxygen is not, which was never previously observed in the literature. Secondary ion mass spectroscopy and transmission electron microscopy were both used to observe and study the presence of Cl. Simulations such as SRIM and Casino 3.2 were used to confirm that the findings were not a technique artefact. Evidence of dealloying was also observed during the characterisation. Dealloying has long been deemed unlikely in Cl-SCC of austenitic stainless steel, but recent work showed that this may also be an available mechanism for SCC as more and more of the characteristics features of dealloying are observed. The dealloying signs observed were: nanoporosity, found on fracture surfaces; severe striations, heavy dissolution of slip planes; element migration (areas of light and dark contrast in back scattered electron images, dictated by the migration of Cr); cleavage failure; Cr and Ni migration around the crack. The role of salt loading was investigated. Different levels of salt deposition were tested in order to obtain an engineering threshold for salt deposition, namely: low ( < 5.70 x 10-3 g cm-2), medium (5.70 x 10-3–1.42 x 10-2 g cm-2) and high ( > 1.42 x 10-2 g cm-2). A linear relationship was observed between level of salt deposited and both crack density and corrosion area. However, more work is necessary to obtain a threshold.
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Ma, Qianmin. "Chloride transport and chloride induced corrosion of steel reinforcement in sodium silicate solution activated slag concrete." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602593.
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Sodium silicate solution (or water glass, WG) activated slag is one of the potential alternatives to 100% replace PC. WG activated slag concrete has different pore solution composition from that of PC. This could result in different chloride transport and corrosion of embedded steel for such concretes. In this research, chloride transport and resulting corrosion of steel in 12 WG activated slag concretes with Na20% of 4, 6 and 8 and Ms of 0.75, 1.00, 1.50 and 2.00 were investigated. PC concrete with the same binder content of 400kg/m3 was studied as a reference. The results showed that the corrosion rate of the steel in the WG activated slag concretes was comparable or even higher than that of the PC concrete irrespective of the lower chloride diffusivity of the former. The WG activated slag concrete with the combination ofNa20% of 6% and Ms of 1.50 gave the lowest chloride diffusivity and corrosion rate. Chloride migration coefficient, ASTM C 1202 charge passed and bulk electrical resistivity had a poor correlation with non-steady state chloride diffusion coefficient for WG activated slag concretes. The criteria of macro cell corrosion current and half-cell potential developed in PC may be not suitable for quantifying and qualifying corrosion activity of the steel in such concretes. The WG activated slag concretes were identified to be not suitable in chloride exposures XS3 and XD3 by considering workability, compressive strength, pore solution composition and corrosion rate.
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Adiyastuti, Sri Murti Civil & Environmental Engineering Faculty of Engineering UNSW. "Influence of cracks on chloride induced corrosion in reinforced concrete flexural members." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/31878.
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The penetration of chloride ions plays a crucial role in reinforcement corrosion and affects the durability and service life of marine structures. The problem is even more acute once cracking occurs in a concrete member. The presence of cracks is shown to have a significant impact on chloride penetration into concrete. It has been recognized, for concrete cracked in flexure, the chloride diffusion coefficient in the tension zone is higher than that in the compression zone. Even a single crack in the tensile zone could contribute to a higher diffusion coefficient compared to that of uncracked members. In this study, the influence of flexural cracks on chloride ion penetration into reinforced concrete beams has been investigated experimentally and a two-dimensional theoretical model is developed. The experimental study investigated the influence of multiple flexural cracks on the chloride diffusivity of reinforced concrete beams and on the corrosion rate of reinforcing bars. The size of the reinforced concrete beams tested is 200 x 250 x 2200 mm with 20mm concrete cover. The beams were pre-cracked using a compression testing machine and the crack widths induced were maintained between 0.1 mm to 0.2 mm. The chloride profile was determined after 1 month, 1 year and 2 years of immersion in 3.0% NaCl solution. The measured chloride profiles of the beams with multiple cracks are compared to those obtained from the uncracked (control) beam. An observation was also made on the effect of cracks on the corrosion development of steel bar after two years of immersion in salt solution. Chloride concentration varied linearly with the depth of crack (at crack planes). A twodimensional model using finite element analysis is developed to evaluate the chloride penetration into cracked concrete. This model was used to verify the chloride penetration data which is obtained from the experimental results. The prediction of chloride ingress, using the two dimensional model agrees well with the short-term and long-term chloride profiles.
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Tang, Denglei, and Denglei Tang@gmail com. "Influence of Chloride-induced corrosion cracks on the strength of reinforced concrete." RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080530.091350.
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In marine environments and where de-icing salts are applied, the degradation of reinforced concrete structures due to chloride induced corrosion of the reinforcement is a major problem. The expansive nature of the corrosion process results in cracking of the concrete and eventually spalling. In order to select suitable remedial measures it is necessary to make an assessment of the residual strength and the residual life. In order to investigate the effect of corrosion on bond strength of the reinforcement, specimens comprising square prismatic sections containing steel reinforcement in the four corners have been subjected to a wet-dry cycle and corrosion has been accelerated by polarising the bars. The research has studied the change of bond strength with level of corrosion for 12 mm and 16 mm bars with concrete cover of 1 and 3 times the bar size. The bond strength is assessed by means of pull out tests and the corresponding extent of corrosion has been assessed in terms of the mass loss. Observations and measurements of the form of the corrosion (pit dimensions and loss of bar diameter) are also presented. The relationship between bond strength and surface crack width has been investigated. Results show that the surface crack width may be a good indicator of residual bond strength. In addition, the influence on bond strength of concrete compressive strength, reinforcement cover, bar position and bar size on the change of bond strength has been explored. It should be noted that all conclusions drawn in this project are based on tests on specimens without shear reinforcement (unconfined) and that accelerated corrosion (by impressed current) has been adopted. Consequently, care should be exercised in applying these results directly to structures in the field. Additional research is needed to assess the influence of impressed current on crack patterns and the effect of shear reinforcement.
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Bosch, Giner Juan. "Chloride and Carbonation Induced Corrosion of Steel in Fly Ash Geopolymer Pore Solution." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627755030968028.
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Marcotte, Tracy Dawn. "Characterization of chloride-induced corrosion products that form in steel-reinforced cementitious materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ65251.pdf.
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Xie, Yi. "Chloride-Induced Stress Corrosion Cracking in Used Nuclear Fuel Welded Stainless Steel Canisters." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469132001.
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Busba, Ezeddin Rafaa. "Effect of Localized Corrosion of Steel on Chloride-Induced Concrete Cover Cracking in Reinforced Concrete Structures." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4872.
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Abstract: Concrete cover cracking due to reinforcement corrosion is widely accepted as a limit-state indicator in defining the end of functional service life for existing reinforced concrete (RC) structures undergoing corrosion. Many of the currently available durability prediction models are incapable of providing realistic estimates of remaining service lives of RC structures beyond the corrosion initiation point. Therefore, the need to incorporate the length of the corrosion propagation stage in a comprehensive durability prediction approach has recently received much research attention. Previous research focus however was mostly limited to the case of uniformly corroding reinforcement with only few studies addressing the commonly encountered case of localized rebar corrosion. It was empirically shown in a previous study that localized corrosion can have a mitigating effect on time to concrete cover cracking due to the larger required depth of rebar corrosion penetration (Critical penetration or Xcrit). The present research was focused on developing a model for predicting Xcrit for various degrees of corrosion localization including new cases of highly localized corrosion. Accelerated corrosion testing of controlled anodic regions along axial rebars in sound concrete cylinders suggested that localized corrosion can increase Xcrit by up to about a factor of 10. The effect of corrosion localization on the orientation of corrosion-induced surface cracks was also addressed. Testing of freely corroding pre-cracked RC pipe specimens in a chloride-containing environment indicated that steel corrosion can be localized at intersection regions with the pre-existing cracks and uniformly distributed around the reinforcing steel perimeter. Numerical modeling was undertaken to substantiate the experimentally observed trends on a theoretical basis for various degrees of corrosion localization. A mechanical model was developed to improve understanding of the underlying mechanism responsible for corrosion-induced stresses. A thick-walled multiple-cylinder approach was employed to simulate crack initiation and propagation to account for the residual strength property of concrete after cracking by applying the principles of applied elasticity. For a given concrete cover depth, the amount of Xcrit was shown by modeling to be largely determined by the length of corroding region and the capacity of the induced cracks to accommodate produced rusts. The properties of both concrete-rebar interface and corrosion products were also found to have a significant impact on Xcrit. Based on the model and experimental trends and comparisons with literature data, an improved relationship for the estimation of Xcrit was proposed. An electrochemical model was also formulated to address the possible role of corrosion aggravation due to macrocell coupling in counteracting the mitigating effect of increased Xcrit on time to concrete cover cracking. Findings confirmed that corrosion localization can reasonably be considered a mitigating factor for extending the corrosion propagation stage, and provided more precise quantification to that effect.
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Chabi, Parham. "Comparative Investigation of Detection Techniques for Chloride-induced Corrosion of Loaded Reinforced Concrete Slabs." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23170.
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This study involved a comparative investigation of chloride-induced corrosion detection techniques on loaded reinforced concrete slabs which were exposed to deicing salts and wetting-drying cycles to simulate typical aggressive environments in cold climates. The studied techniques involved linear polarization technique, galvanostatic pulse technique, electrochemical impedance spectroscopy, half-cell potential and concrete electrical resistivity mapping. The results showed that concrete quality and moisture content have a direct effect on corrosion activity, and these properties are represented well with concrete electrical resistivity. The galvanostatic pulse technique was shown to correlate well with electrochemical impedance spectroscopy, which was used as a benchmark for corrosion rate measurements in this study; however, the galvanostatic pulse technique was not capable of detecting corrosion activity in saturated concrete accurately. The results of this research do not support the criteria provided by the ASTM C876-09 standard for using half-cell potentials to estimate the probability of reinforcing steel corrosion in reinforced concrete structures.
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Bateman, Kaylee Dee. "Estimating Phase Durations for Chloride-Induced Corrosion Damage of Concrete Bridge Decks in Utah." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7369.
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Chloride-induced deterioration of concrete bridge decks can be described in terms of three phases: 1) initiation of rebar corrosion, 2) rust formation and development of deck damage, and 3) accelerated deck damage towards structural failure. The first objective of this research was to investigate relationships among chloride concentration at the top mat of reinforcing steel, deck age, cover depth, and occurrence of delamination for concrete bridge decks with selected surface treatments and rebar types. Relating these factors can help establish greater understanding about the duration of each phase of the deterioration process. A second objective of this research was to investigate the relationship between chloride concentrations that develop between the bars and those that develop directly above the bars in the top mat of reinforcing steel to better understand the effects of the presence of reinforcing steel on diffusion of chloride ions through the concrete matrix.Data collected from 48 concrete bridge decks in Utah were used to address both of the objectives stated for this research. Surface treatment types included bare concrete, thin-bonded polymer overlays, and asphalt overlays, and rebar types included uncoated and epoxy-coated rebar. Regarding the first objective, baseline relationships between chloride concentration, deck age, and cover depth were developed for all three deck types. The results show that, as deck age increases, chloride concentration also increases and that chloride concentrations are much higher for shallower concrete depths than for deeper concrete depths. Based on these relationships, the duration of the first phase of the deterioration process was estimated using the critical chloride threshold of 2.0 lb Cl-/yd3 of concrete. For decks with asphalt or polymer overlays, development of clear relationships between chloride concentration, deck age, and cover depth required consideration of treatment time. The data show that chloride concentrations for decks that had an overlay applied 10 or more years after construction are higher than those for decks that had an asphalt overlay applied immediately after construction. Relevant to determining the duration of the second phase of the deterioration process, the relationship between delamination occurrence and chloride concentration for bare concrete bridge decks was developed. In general, the results show that the occurrence of delamination increases with increasing chloride concentration. Estimated durations of the second phase of the deterioration process were then determined using a chloride concentration threshold of 4.0 lb Cl-/yd3 of concrete for each of the same combinations of surface treatment and cover depth used for determining durations of the first phase of the deterioration process. Regarding the performance of epoxy-coated bar, the data clearly demonstrate the benefit of epoxy coatings on reinforcing steel for the purpose of significantly delaying the onset of chloride-induced delamination in concrete bridge decks. The relationship between the ratio of chloride concentrations directly above and between steel reinforcing bars and deck age was then developed. The results show that, as deck age increases, the average ratio of chloride concentrations directly above and between the bars asymptotically decreases from above 1.5 toward 1.0, which is reached at a deck age of approximately 30 years. Given that increasing deck age generally corresponds to increasing chloride concentration, which would in turn eventually lead to similar chloride concentrations directly above and between bars as the concrete pore water within the cover depth approached chloride saturation, this observed relationship is consistent with theory.
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Nordgren, Eric. "The effect of metallurgical structure on the chloride-induced corrosion of archaeological wrought iron." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/97535/.
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Archaeological wrought iron artefacts are subject to damaging corrosion while in the burial environment and when subjected to environmental changes after excavation. The role of water, oxygen, and chloride corrosion accelerators are central to iron corrosion processes. Intrinsic factors such as the amount and distribution of slag in wrought iron may also play a role in corrosion processes. This study examined a range of factors that impact on understanding conservation desalination treatments to mitigate corrosion by removing chlorides. While examining the effect of slag on corrosion rate and chloride content formed the core of this project, cracking morphologies within corrosion product layers and their influence on corrosion rates measured by oxygen consumption produced outcomes of interest for designing the practicalities of treatment procedures. The slag content of the wrought iron objects examined in this study did not correlate with either their corrosion rate or their chloride content. In line with other authors, clustering of chloride around slag inclusions was identified. This confirmed slag does act as a focus for developing corrosion centres, which will offer challenges for chloride removal and hence provide opportunity for post-treatment corrosion. The alkaline sulphite washing applied to the iron nails produced results that aligned with those reported in other studies and confirmed its relative efficiency for removing chloride. Of major relevance to conservators designing alkaline washing techniques is assigning treatment time and specifying treatment environment. These decisions are aided by evidence provided in this study, which showed that immersing the chloride ii containing corrosion product β-FeOOH in alkaline sulphite entirely transformed it to other iron oxides in only 30 days. During this process it will release its chloride, which will be available for diffusion into the wash solution making a more complete desalination process possible.
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Kirkpatrick, Trevor Joe. "Impact of Specification Changes on Chloride Induced Corrosion Service Life of Virginia Bridge Decks." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34056.
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A model to determine the time to first repair and subsequent rehabilitation of concrete bridge decks exposed to chloride deicer salts that recognizes and incorporates the statistical nature of factors affecting the corrosion process is developed. The model expands on an existing deterministic model using statistical computing techniques, including resampling techniques such as the parametric and simple bootstrap. Emphasis was placed on the diffusion portion of the diffusion-cracking model, but advances can be readily included for the time for corrosion deterioration after corrosion initiation.
Data collected from ten bridge decks built in Virginia between 1981 and 1994 was used to model the surface chloride concentration, apparent diffusion coefficient, and clear cover depth. Several ranges of the chloride corrosion initiation concentration, as determined from the available literature, were investigated. The time to first repair and subsequent rehabilitation predicted by the stochastic model is shorter than the time to first repair and subsequent rehabilitation predicted by the deterministic model, but is believed to more accurately reflect the true nature of bridge deck deterioration.
The model was validated using historical service life data for 129 bridge decks built in Virginia between 1968 and 1972. The time to rehabilitation predicted for the set of bridge decks built between 1981 and 1994 by the stochastic model was approximately 13 years longer than the normalized time to rehabilitation projected for the bridge decks built between 1968 and 1972 using historical data. The increase in time to rehabilitation for the newer set of bridge decks was attributed to a reduction in the specified maximum water/cement ratio and increase in clear cover depth.Master of Science
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Walker, Robert J. "Aspects of the prevention and repair of chloride-induced corrosion of steel in concrete." Thesis, Aston University, 1994. http://publications.aston.ac.uk/14301/.
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Sodium formate, potassium acetate and a mixture of calcium and magnesium acetate (CMA) have all been identified as effective de-icing agents. In this project an attempt has been made to elucidate potentially deleterious effects of these substances on the durability of reinforced concrete. Aspects involving the corrosion behaviour of embedded steel along with the chemical and physical degradation of the cementitious matrix were studied. Ionic diffusion characteristics of deicer/pore solution systems in hardened cement paste were also studied since rates of ingress of deleterious agents into cement paste are commonly diffusion-controlled. It was found that all the compounds tested were generally non-corrosive to embedded steel, however, in a small number of cases potassium acetate did cause corrosion. Potassium acetate was also found to cause cracking in concrete and cement paste samples. CMA appeared to degrade hydrated cement paste although this was apparently less of a problem when commercial grade CMA was used in place of the reagent grade chemical. This was thought to be due to the insoluble material present in the commercial formulation forming a physical barrier between the concrete and the de-icing solution. With the test regimes used sodium formate was not seen to have any deleterious effect on the integrity of reinforced concrete. As a means of restoring the corrosion protective character of chloride-contaminated concrete the process of electrochemical chloride removal has been previously developed. Potential side-effects of this method and the effect of external electrolyte composition on chloride removal efficiency were investigated. It was seen that the composition of the external electrolyte has a significant effect on the amount of chloride removed. It was also found that, due to alterations to the composition of the C3A hydration reaction products, it was possible to remove bound chloride as well as that in the pore solution. The use of an external electrolyte containing lithium ions was also tried as a means of preventing cathodically-induced alkali-silica reaction in concretes containing potentially reactive aggregates. The results obtained were inconclusive and further practical development of this approach is needed.
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Rohaya, Abdul Malek. "Assessment of Chloride Induced Corrosion and Impressed Current Cathodic Protection Conditions in Repaired Reinforced Concrete." Kyoto University, 2018. http://hdl.handle.net/2433/231995.
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Sola, Emiliano [Verfasser], and Joško [Akademischer Betreuer] Ožbolt. "Experimental and numerical study of chloride induced corrosion in reinforced concrete / Emiliano Sola ; Betreuer: Joško Ožbolt." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1158597932/34.
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Wang, Junjie. "Influence of structural cracks in concrete on transport properties and chloride-induced corrosion of steel reinforcement." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676607.
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Chloride-induced corrosion of steel in reinforced concrete structures is one of the main problems affecting their durability, but most previous research projects and case studies have focused on concretes without cracks or not subjected to any structural load. Although it has been recognised that structural cracks do influence the chloride transport and chloride induced corrosion in reinforced concrete structures, there is little published work on the influence of microcracks due to service loads on these properties. Therefore, the main objective of this research was to identify to what extent microcracks due to structural loads affect the chloride transport and chloride-induced corrosion in reinforced concrete structures and thereby make recommendations for any change of service life designs of such structures. Three stages of experiments were carried out. They were the influence of stresses and microcracks on chloride migration, diffusion, sorption and chloride-induced corrosion of steel in concrete. The main findings from this project are: chloride migration coefficients of concrete changed little when the stress level was below 50% of the ultimate stress (fu). A recovery of around 50% of the increased chloride migration coefficient was found in the case of concretes subjected to 75% of the fu when the load was removed. The influence of concrete mixes on chloride diffusion coefficient of concrete could be more significant than that of stress levels when the concrete was subjected to ponding of salt water. The role of cracks was found to be more important when the concrete was subjected to 'sorption + diffusion' compared with concrete subjected to diffusion alone. These finds suggest that the effect of microcracks is very significant for the service life of reinforced concrete structures in aggressive environments. This means that for the service life design of reinforced concrete structures in chloride exposure environments, consideration should be given to microcracks at service loads.
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Zhou, Nian. "Influence of grinding operations on surface integrity and chloride induced stress corrosion cracking of stainless steels." Licentiate thesis, KTH, Yt- och korrosionsvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180817.
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Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes. The central theme of this thesis is the mechanical grinding process. This is commonly used for producing stainless steel components, and results in varied surface properties that will strongly affect their service life. The influence of grinding parameters including abrasive grit size, machine power and grinding lubricant were studied for 304L austenitic stainless steel (Paper II) and 2304 duplex stainless steel (Paper I). Surface integrity was proved to vary significantly with different grinding parameters. Abrasive grit size was found to have the largest influence. Surface defects (deep grooves, smearing, adhesive/cold welding chips and indentations), a highly deformed surface layer up to a few microns in thickness and the generation of high level tensile residual stresses in the surface layer along the grinding direction were observed as the main types of damage when grinding stainless steels. A large degree of residual stress anisotropy is interpreted as being due to mechanical effects dominating over thermal effects. The effect of grinding on stress corrosion cracking behaviour of 304L austenitic stainless steel in a chloride environment was also investigated (Paper III). Depending on the surface conditions, the actual loading by four-point bend was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks initiation on the ground surfaces. Grinding along the loading direction was proved to increase the susceptibility to chloride-induced SCC, while grinding perpendicular to the loading direction improved SCC resistance. The knowledge obtained from this work can provide a reference for choosing appropriate grinding parameters when fabricating stainless steel components; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.QC 20160203
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Ndawula, Joanitta N. "Towards a triphasic Theory of Porous Media-based model for chloride-induced corrosion in reinforced concrete." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31022.
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This thesis is concerned with the initial development of a multiphase material model using the Theory of Porous Media (TPM) for the penetration of intermediary rust product into reinforced concrete subjected to chloride-induced corrosion. Research has shown that although the majority of time-to-cracking service life models for reinforced concrete structures neglect the permeation of rust into the cement paste adjacent to the reinforcement, it is this mechanism that is responsible for discrepancies between experimental data and model results. The model presented may be used to simulate the transport of water and gas through the capillary pores in concrete and the diffusion of iron III chloride within the pore solution. Iron III chloride is a soluble chloride complex formed as an intermediary product during the oxidation reaction at the anode of the corrosion cell. This solute is transported in the pore solution from low oxygen conditions and is oxidized in oxygen-rich conditions resulting in the precipitation of rust in the concrete pores. The Theory of Porous Media has proven proficient for modelling the material behaviour of porous solid bodies saturated with one or more fluids but has yet to be applied to chloride-induced reinforcement corrosion of reinforced concrete. This work outlines the initial efforts of using TPM to model the rust transport process coupled with the poro-elastic material response of reinforced concrete. The latter accounts for the stress build-up due to rust precipitation and volume expansion. The chloride complex is described by a concentration within the liquid phase and is therefore not assigned a unique volume fraction. Precipitation of the rust is not included here as it will be added at a later stage in the development of a more accurate reinforced concrete chloride induced corrosion model. It is intended that the model thus developed may be adapted for other deterioration mechanisms in concrete.
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Farhadi, Mehrnoush. "Finite Element Modeling of Steel Corrosion in Concrete Structures." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85022.
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Concrete is a popular construction material for bridges, due to its high durability and energy efficiency. An important concern for concrete bridges is the possible occurrence of chloride- induced corrosion in prestressing strands and reinforcing bars, which may substantially impact the service life of such structures. Chloride- induced corrosion is a complicated electrochemical process which is affected by heat transfer, moisture flow and transport of chemical species through the concrete pore network. Reliable and robust analytical tools are required to allow multi-physics simulations of steel corrosion.
This study has developed a nonlinear finite element analysis program, called VT-MultiPhys, to enable multi-physics simulations, including analyses of chloride-induced corrosion. The program includes constitutive laws, element formulations and global solution schemes to allow the analysis of steady-state (static) and time-dependent (dynamic) problems, involving multiple, coupled processes such as mechanical deformation, heat transfer, mass flow and chemical reactions combined with advective/diffusive transport of the various species. Special analysis schemes, based on the streamline-upwind Petrov-Galerkin (SUPG) method, have also been implemented to address the spatial instabilities which characterize analyses of advection-dominated transport.
The finite element modeling scheme, constitutive laws and boundary conditions for analysis of chloride-induced corrosion are described in detail. The constitutive laws can be combined with inelastic material models to capture the damage (e.g., cracking) due to chloride-induced corrosion. A set of verification analyses is presented, to demonstrate the capabilities of VT-MultiPhys to conduct different types of simulations and reproduce the closed-form analytical solutions of simple cases. Validation analyses for heat conduction, moisture flow and chloride transport, using data from experimental tests in the literature, are also presented.Master of Science
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Sandberg, Jan. "Corrosion-induced release of zinc and copper in marine environments." Licentiate thesis, Stockholm : Division of corrosion science, Department of materials science end engineering, School of industrial engineering and management, Royal institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4051.
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Mallinson, Christopher F. "The chloride induced localised corrosion of aluminium and beryllium : a study by electron and X-ray spectroscopies." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/809467/.
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Beryllium is an important metal in the nuclear industry for which there are no suitable replacements. It undergoes localised corrosion at the site of heterogeneities in the metal surface. Corrosion pits are associated with a range of second phase particles. To investigate the role of these particles in corrosion, a safe experimental protocol was established using an aluminium alloy as a corrosion material analogue. The 7075-T6 alloy had not previously been investigated using the experimental methodology used in this thesis. This work led to the development of the experimental methodology and safe working practices for handling beryllium. The range and composition of the second phase particles present in S-65 beryllium billet were identified using a combination of SEM, AES, EDX and WDX. Following the identification of a range of particles with various compositions, including the AlFeBe4 precipitate which has been previously associated with corrosion, the location of the particles were marked to enable their repeated study. Attention was focused on the microchemistry in the vicinity of second phase particles, as a function of immersion time in pH 7, 0.1 M NaCl solution. The corrosion process associated with different particles was followed by repeatedly relocating the particles to perform analysis by means of SEM, AES and EDX. The use of traditional chlorinated vapour degreasing solvents on beryllium was investigated and compared to two modern commercially available cleaning solutions designed as drop-in replacements. This work expanded the range of solvents suitable for cleaning beryllium and validated the conclusions from previous thermodynamic modelling. Additionally, a new experimental methodology has been developed which enables the acquisition of chemical state information from the surface of micron scale features.
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Zhao, Li. "SPATIAL RELIABILITY ANALYSIS FOR CORRODED REINFORCED CONCRETE STRUCTURES." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1479123930240399.
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Zhao, Weijie. "Corrosion initiation induced by sodium sulfate and sodium chloride particles on Cu and the golden alloy Cu5Al5Zn at simulated atmospheric conditions." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219471.
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Effects of sodium sulfate (Na2SO4) particle deposition on the atmospheric corrosion of copper (Cu) metal and a Cu-based alloy (Cu5Al5Zn) used in architectural applications were investigated at laboratory conditions compared with effects induced by sodium chloride (NaCl) and to some extent ammonium sulfate (NH4)2SO4 induced corrosion. Pre-deposited surfaces were exposed to repeated wet/dry conditions in a climatic chamber and the formation of corrosion products were assessed using light optical microscopy (LOM), scanning electron microscopy with elemental analysis (SEM/EDS), Fourier transform infrared techniques (FTIR microscopy) and cathodic reduction (CR). Na2SO4 induced corrosion resulted in corrosion cells locally over the surface on both Cu and Cu5Al5Zn, of increased oxygen content in the anodic area of the cells (center of pre-deposited area). The main corrosion products formed on Cu metal are basic copper sulfates and cuprite (Cu2O), while basic sulfates (copper and/or zinc) and Cu2O were the main corrosion products formed on Cu5Al5Zn. A combined deposition of Na2SO4 + NaCl was carried out on the Cu5Al5Zn alloy using two different deposition methods to investigate the possible interplay from a corrosion initiation perspective between the two salt particles. For short time exposed Cu5Al5Zn (1 cycle), two different corrosion cells formed, mainly induced by Na2SO4 and NaCl. Corrosion products formed in anodic areas of a Na2SO4 induced corrosion cell were similar to findings observed for Cu5Al5Zn pre-deposited with Na2SO4 only, whereas peripheral cathodic areas primarily were affected by NaCl dissolution and predominantly composed of Cu2O that was the main corrosion product with small amount of hydroxides and carbonates of the NaCl induced corrosion cells. After relatively longer exposure periods (2 and 6 wet/dry cycles), NaCl dominated the corrosion of the entire surface with the formation of more Cu2O, hydroxides and carbonates. Cathodic reduction findings revealed a negative interplay on corrosion for the mixed salt after short time exposures (1 and 2 cycles), whereas a slight synergistic effect was evident after a longer exposure period (6 cycles), compared with corrosion induced by single salts.
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Otieno, Mike Benjamin. "The development of empirical chloride-induced corrosion rate prediction models for cracked and uncracked steel reinforced concrete structures in the marine tidal zone." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9520.
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Includes bibliographical references.Empirical chloride-induced corrosion rate prediction models for cracked and uncracked reinforced concrete (RC) structures in the marine tidal exposure zone are proposed in this study. The data used to develop the models were obtained from parallel corrosion experiments carried out by exposing half of 210 beam specimens to accelerated laboratory corrosion (cyclic 3 days wetting with 5% NaCl solution followed by 4 days air-drying) while the other half were left to undergo natural corrosion in a marine tidal zone in Cape Town (Table Bay). The main experimental variables were pre-corrosion flexural cover cracking, cover depth and concrete quality (binder type and w/b ratio). Corrosion rate, half-cell potential and concrete resistivity were monitored bi-weekly throughout the experimental period. The experimental results show that even though each of the variables investigated affects corrosion rate in a certain manner, their combined influence is complex. In general, regardless of the exposure environment (laboratory or marine tidal zone), for a given concrete quality and cover depth, pre-corrosion cover cracking was found to result in higher corrosion rates than in uncracked concrete, but with the field corrosion rates being much lower than the corresponding laboratory ones. Even though corrosion rates in both the field and laboratory specimens increased with an increase in crack width, the influence of concrete quality and cover depth was still evident. However, the effect of cover cracking on corrosion rate diminished with increasing concrete quality. In the blended cement concretes, the effect of concrete quality is further diminished by the inherent high resistivities of these concretes. The increase in corrosion rate due to increase in crack width, regardless of w/b ratio and cover depth, was generally higher in the 100% CEM I 42.5N concrete specimens than in the blended ones. A framework is proposed that can be used to objectively compare predicted corrosion rates for specimens with similar concrete quality (influenced by binder type and w/b ratio) but different cover depths and crack widths. The framework, which incorporates the combined influence of cover depth, crack width and concrete quality (quantified using chloride diffusion coefficient) on corrosion rate, is the basis of the proposed corrosion rate prediction models for cracked concrete. Sensitivity analyses on the proposed models show that if any two of the three input parameters (cover depth, crack width and concrete quality) are simultaneously varied, their effect on corrosion rate is dependent on the value of the third (unchanged) parameter. Furthermore, (i) the initial cover depth was found to have no effect on the extent to which a change in cover depth affects corrosion rate; a similar trend was found in the case of sensitivity of corrosion rate to change in crack width , and (ii) the extent to which a change in either crack width or cover depth affects corrosion rate is dependent mainly on the concrete quality. In general, the sensitivity analyses showed that corrosion rate is more sensitive to change in concrete quality than crack width and cover depth. The proposed models can be used to (i) quantify the propagation phase with respect to a given performance limit using relevant corrosion-induced damage prediction models, and (ii) select suitable design combinations of cover depth, concrete quality and crack width to meet the desired durability performance of a given RC structure in the marine environment.
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Zhu, Weiqi, and ycqq929@gmail com. "An Investigation into Reliability Based Methods to Include Risk of Failure in Life Cycle Cost Analysis of Reinforced Concrete Bridge Rehabilitation." RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080822.140447.
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Reliability based life cycle cost analysis is becoming an important consideration for decision-making in relation to bridge design, maintenance and rehabilitation. An optimal solution should ensure reliability during service life while minimizing the life cycle cost. Risk of failure is an important component in whole of life cycle cost for both new and existing structures. Research work presented here aimed to develop a methodology for evaluation of the risk of failure of reinforced concrete bridges to assist in decision making on rehabilitation. Methodology proposed here combines fault tree analysis and probabilistic time-dependent reliability analysis to achieve qualitative and quantitative assessment of the risk of failure. Various uncertainties are considered including the degradation of resistance due to initiation of a particular distress mechanism, increasing load effects, changes in resistance as a result of rehabilitation, environmental variables, material properties and model errors. It was shown that the proposed methodology has the ability to provide users two alternative approaches for qualitative or quantitative assessment of the risk of failure depending on availability of detailed data. This work will assist the managers of bridge infrastructures in making decisions in relation to optimization of rehabilitation options for aging bridges.
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Holland, Robert Brett. "Durability of precast prestressed concrete piles in marine environments." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44859.
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In this research, two phases of work were conducted. First, an investigation into the durability concerns for precast prestressed concrete piles exposed to marine environments was conducted. The investigation characterized the durability concerns of chemical, biological, and physical deterioration mechanisms. The results of this study were used to develop potential high performance marine concretes (HPMC) that would be capable of 100+ year service lives in marine environments. Extensive durability testing and service life modeling of the HPMC was performed. Chloride ingress resistance was investigated using accelerated and long-term test procedures and the results used to perform service life modeling to predict the time before corrosion initiation. Sulfate resistance characterization was performed using multiple techniques to characterize the physical and chemical behavior of binder compositions containing binary or ternary mixes containing cement and supplementary cementitious materials (SCM's) subjected to a sulfate-laden environment. Accelerated carbonation testing and material characterization led to the finding of relationships in the chemical composition of mix designs and the observed durability and the results used to perform corrosion initiation service life modeling. An investigation into the influence of self-healing of cracked concrete led to fundamental findings on the behavior of chloride ingress for cracked concrete structures in marine environments. The results of this research led to the development of concrete mix designs capable of providing service lives over 100 years in Georgia's marine environments, as well as the advancement of the current state of knowledge on the durability characteristics of ternary mix designs.
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Jackobasch, Andreas, Ulrich Schneck, and Christoph Grieger. "Zerstörungsfreie Prüfung von Stahlbeton." Hochschule für Technik und Wirtschaft Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:520-qucosa-163090.
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Das Ziel der Arbeit bestand darin, die aus der Literatur bekannten Zusammenhänge zwischen Korrosionsaktivität von Stahl im Beton und einer galvanostatischen Pulsmessung, welche unter Laborbedingungen gute Ergebnisse liefern, auf Messungen an realen Bauwerken anzuwenden.
Dazu wurden zunächst Untersuchungen an 13 Jahre alten Prüfkörpern durchgeführt und ausgewertet. Die abgeleiteten Zusammenhänge konnten anschließend an realen Bauteilen verifiziert werden. Somit stellt die galvanostatische Pulsmessung eine hilfreiche zerstörungsfreie Prüfmethode zur Interpretation des Korrosionszustandes dar. Die neuen Erkenntnisse lassen eine bessere Einschätzung des Korrosionsverhaltens in Stahlbetonbauwerken zu, als es die Potentialmessung erlaubt.
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Garcia, David. "Études exploratoires dédiées au diagnostic de corrosion assisté par ordinateur des structures de génie civil." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30247.
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La thèse "Études exploratoires dédiées au diagnostic de corrosion assisté par ordinateur des structures de génie civil" traite de la phénoménologie et de la modélisation de la corrosion de l'acier de construction. Le poids sécuritaire, sociétal, environnemental du vieillissement des infrastructures fait de ce thème un enjeu économique majeur de développement de tout pays. Les développements proposés portent principalement sur la corrosion des armatures dans le béton armé. La corrosion des structures métalliques enterrées est également adressée concernant les problématiques relatives aux couplages galvaniques induits par l'hétérogénéité des sols et aux courants vagabonds. Les méthodes d'investigation usuelles (mesures de potentiel des aciers, de résistivité du béton ou de résistance de polarisation), jointes à des hypothèses empiriques consacrées par l'usage, conduisent à des interprétations souvent incertaines ou n'ayant qu'une valeur qualitative. L'ambition de cette thèse, motivée par les enjeux évoqués, est de montrer comment une meilleure compréhension de la physique de la corrosion, conjuguée à la puissance du calcul aux éléments finis, permet de construire des modèles élaborés et robustes, utiles pour poser un diagnostic et/ou un pronostic quantifié et fiable. La thèse est abondamment illustrée par des études de cas réels ou numériques et étayée par des essais originaux conduits en laboratoire. Afin d'améliorer la compréhension des phénomènes prévalant dans le processus de corrosion, les concepts-clés de thermodynamique et de cinétique électrochimique sont rappelés et contextualisés. L'assemblage de différentes lois physiques, chimiques et électrochimiques permet d'élaborer une approche de modélisation avancée, intégrant notamment la diffusion du dioxygène jusqu'aux armatures en contexte insaturé, mais aussi la production et la précipitation des produits de la corrosion et leur influence sur l'équilibre dynamique d'un système de corrosion. Cette approche de modélisation, nécessairement tridimensionnelle ou a minima bidimensionnelle, donne lieu à une transcription dans un code de calcul par éléments finis. Elle est appliquée dans un premier temps à l'étude numérique d'un premier cas typique de corrosion : pile en béton armé partiellement immergée en mer. L'influence du rôle du dioxygène (disponibilité et diffusion) sur la cinétique de dissolution de l'acier et sur la nature des produits de corrosion formés est notamment étudiée. Afin d'illustrer l'apport effectif de la modélisation 3D dans le processus de diagnostic de la corrosion, une étude de cas réelle est proposée concernant un ouvrage métallique enterré, en l'occurrence des palplanches servant au soutènement des culées d'un passage supérieur d'autoroute, situées à proximité d'une conduite enterrée sous protection cathodique. Des mesures effectuées in-situ mais aussi en laboratoire à partir d'échantillons judicieusement choisis, permettent d'alimenter le modèle de calcul. Le modèle numérique ainsi construit, qualifié de jumeau numérique, permet de mettre en évidence l'existence de courants vagabonds circulant dans la structure, mais également le risque de corrosion galvanique induit par l'hétérogénéité du sol. Le jumeau numérique électrochimique constitue alors un outil puissant pour estimer la cinétique et le faciès de corrosion de l'ouvrage et poser un pronostic en termes de durée de vie. [...]The PhD thesis "Exploratory studies dedicated to computer-assisted corrosion diagnosis of civil engineering structures" deals with the phenomenology and modeling of corrosion of structural steel. The safety, societal and environmental impact of aging infrastructures makes this theme a major economic issue for the development of any country. The proposed developments focus mainly on the corrosion of reinforcements in reinforced concrete. The corrosion of buried metallic structures is also addressed concerning the problems related to galvanic couplings induced by the heterogeneity of soils and stray currents. The usual methods of investigation (measurements of steel potential, concrete resistivity or polarization resistance), combined with empirical hypotheses established by experience, lead to interpretations that are often uncertain or have only a qualitative value. The ambition of this thesis, motivated by the issues at stake, is to show how a better understanding of the physics of corrosion, combined with the power of finite element calculation, allows the construction of elaborate and robust models, useful for a quantified and reliable diagnosis and/or prognosis. The thesis is abundantly illustrated by real or numerical case studies and supported by original laboratory tests. In order to improve the understanding of the phenomena prevailing in the corrosion process, the key concepts of thermodynamics and electrochemical kinetics are recalled and contextualized. The assembly of different physical, chemical and electrochemical laws allows the elaboration of an advanced modeling approach, integrating in particular the diffusion of oxygen to the reinforcement in an unsaturated context, but also the production and precipitation of corrosion products and their influence on the dynamic equilibrium of a corrosion system. This modeling approach, necessarily three-dimensional or at least two-dimensional, gives rise to a transcription in a finite element calculation code. It is first applied to the numerical study of a first typical case of corrosion: a reinforced concrete pile partially submerged in the sea. The influence of the role of oxygen (availability and diffusion) on the dissolution kinetics of the steel and on the nature of the corrosion products formed is studied in particular. In order to illustrate the effective contribution of 3D modeling in the process of corrosion diagnosis, a real case study is proposed concerning a buried steel structure, in this case sheet piles used to support the abutments of a freeway overpass, located near a pipe buried under cathodic protection. Measurements carried out in-situ but also in the laboratory from judiciously chosen samples are used to feed the calculation model. The numerical model thus constructed, qualified as a digital twin, makes it possible to highlight the existence of stray currents circulating in the structure, but also the risk of galvanic corrosion induced by the heterogeneity of the soil. The electrochemical digital twin is then a powerful tool for estimating the kinetics and the corrosion facies of the structure and making a prognosis in terms of service life. Within a concrete structure, the presence of chlorides is associated with various effects, notably associated with the local electric field. If this phenomenon is ignored, the interpretation of field data, for example potential maps, can lead to a biased diagnosis. This thesis addresses the question of corrosion initiation.[...]
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Licardie, Giezi A. "Aggressive chlorine induced corrosion of embedded reinforced concrete /." Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1079666041&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Viklund, Peter. "High temperature corrosion during waste incineration : characterisation, causes and prevention of chlorine-induced corrosion." Licentiate thesis, Swerea KIMAB AB, Stockholm, Sweden, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32412.
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Waste-fired boilers suffer severely from corrosion of critical components such as superheater tubes. In this work the high temperature corrosion of candidate superheater alloys have been investigated by detailed laboratory studies and controlled field exposures in full-scale boilers. In a laboratory study the detrimental effect of gaseous hydrochloric acid (HCl) on three different ground surface and preoxidised austenitic stainless steels was investigated. Exposures were conducted in an environment comprising N2-10O2-5H2O-0.05HCl at both 400 °C and 700 °C. A positive effect of preoxidation is evident when the alloys are exposed at 400 °C. Oxide layers formed during preoxidation effectively suppress chlorine ingress and lower the corrosion rate for all three materials while accelerated corrosion and chlorine accumulation at the metal/oxide interface is detected for ground surface specimens. The positive effect of preoxidation is lost at 700 °C and corrosion resistance is dependent on alloying level. At 700 °C metal chloride evaporation contributes significantly to the material degradation. Based on the results, high temperature corrosion in the presence of gaseous HCl is discussed in general terms. In two different waste-fired boilers measures for counteracting superheater corrosion were investigated. In a grate-boiler the deposit formation and high temperature corrosion of some candidate superheater materials were studied. Metal loss measurements showed unacceptably high corrosion rates for the lower alloyed ferritic steels 13CrMo44 (Fe-1Cr-0.5Mo) and HCM12A (Fe-11Cr-2W), as well as for the austenitic Super 304 (Fe-18Cr-9Ni-3Cu). The corrosion attack for these alloys was manifested by the formation of mixed metal chloride/metal oxide scales. A different type of behaviour was seen for the higher alloyed austenitic steels and nickel-base alloys, which were able to form a chromium-enriched oxide next to the metal. However, the alloys suffered from localised pitting attack. Since analyses of the deposit revealed appreciable amounts of low melting salt mixtures such as ZnCl2-KCl, PbCl2-KCl, FeCl2-KCl and NaCl-NiCl2, oxide dissolution in these molten salts is the probable reason for pitting attack. In a waste-fired boiler ammonium sulphate solution was added to the flue gas and the effect on flue gas and deposit composition was evaluated. It was evident that the sulphur-rich additive reduced the amount of alkali chlorides in both the flue gas and the deposit. Results also indicated that the initial corrosion rates were lowered with the use of ammonium sulphate. It was concluded that using the additive could be a possible strategy for changing the flue gas chemistry so that superheater corrosion is mitigated.QC 20110414
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Marshall, Becki Jean. "Initiation, Propagation, and Mitigation of Aluminum and Chlorine Induced Pitting Corrosion." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35798.
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Previous research by Rushing et al. (2002) identified key factors contributing to the formation of pinhole leaks in copper plumbing. These factors included high chlorine, pH levels and the presence of aluminum solids. Experiments were conducted to 1) examine the interplay between these constituents, 2) confirm that the water was aggressive enough to eat a hole through a pipe, 3) examine phosphate inhibition, and 4) try to determine the scope of this pitting problem in other distribution systems and on a national level.
The first set of experiments clearly defined the controversial trends from earlier work. At certain pH values, the presence of chlorine and aluminum solids does seem to initiate pitting corrosion of copper. Although the problem is most severe at higher pH, it is likely that long-term exposure at lower values such as pH 8 could lead to pitting. There is a concentration effect of aluminum solids at pH 9.0, in that higher concentrations cause an earlier rise in the potential for copper to corrode if sufficient chlorine is present.
The second phase of experiments are the first to prove that a potable water containing aluminum, high chlorine residual, and relatively high pH can cause pinholes in copper tube. To our knowledge this is the first time the phenomenon of pinhole leaks has been reproduced in the laboratory as it occurs in the field. It therefore proves that "aggressive water" alone can cause the problem of pitting. The role of flow, pipe orientation and hypothesized surface defects was directly examined as part of this evaluation. Pitting increased with greater water usage and for sections of straight pipe exposed to hydraulic conditions near bends. Copper pipe sections polished to a mirror like finish to remove surface defects were also severely attacked.
The role of phosphate in mitigation of copper pitting corrosion was defined in a subsequent experiment using synthesized water. Phosphates did not have an effect at pH 7.7 and were found to reduce electrochemical indications of pitting in the synthetic water at the pH of 8.3. Phosphates had lesser benefits at higher pH even in synthetic water, but overall, even at pHs as high as 10, some benefits from orthophosphate dosing might be anticipated.
Effects of orthophosphate on the inhibition of copper pitting corrosion were then applied to treated water from a utility in Washington D.C., whose consumers have experienced an outbreak of pinhole leaks in household copper plumbing. After comparing electrochemical results from synthetic and actual water from the treatment plant, there was evidence of a natural inhibitor to pitting corrosion in WSSC water that is not present in the synthetic water. The higher chloride concentration in the water after ferric chloride was dosed at the treatment plant may have reduced the pitting propensity of the water. The effects of phosphates seemed to reduce the pitting propensity of real water at pH 8.3 although little benefit was seen at pH 9.1.
These defined characteristics of copper pitting were then applied in a systematic evaluation of a water utility experiencing pitting corrosion in Roanoke, VA. This case study further supported the hypothesis that high levels of aluminum, chlorine, and pH may be combining to catalyze copper pitting in practice. Recommendations to alter the treatment strategies at these utilities were proposed to help mitigate the pitting corrosion problems in these areas. A national survey then confirmed pitting is occurring at a significant frequency at other large utilities across the U.S.
Master of Science
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Alonso, Herranz Elisa [Verfasser]. "Short-term measurement of high-temperature chlorine-induced corrosion and agglomeration during biomass and waste combustion / Elisa Alonso Herranz." München : Verlag Dr. Hut, 2012. http://d-nb.info/1021072958/34.
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Alonso, Herranz Elisa [Verfasser], Hartmut [Akademischer Betreuer] Spliethoff, and F. [Akademischer Betreuer] Haider. "Short-term measurement of high-temperature chlorine-induced corrosion and agglomeration during biomass and waste combustion / Elisa Alonso Herranz. Gutachter: F. Haider. Betreuer: Hartmut Spliethoff." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1020484926/34.
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Wijaya, Fransisca, and 梁淑玲. "Seismic Evaluation of Low-rise Reinforced Concrete Street Houses with Chloride Induced Reinforcement Corrosion using Pushover Analysis." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/38901993167911133401.
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碩士國立臺灣科技大學
營建工程系
103
Low-rise reinforced concrete (RC) street houses are very common to be seen in Taiwan. Most of them were built typically with the same configuration of structure plans. As the time goes by, many of those street houses are facing corrosion problem. The corrosion initiates due to the chloride contaminated material used to build those street houses. The street houses have already contained chloride iron content right after the completion of construction. This corrosion problem will lead confusion to engineers to determine the seismic capacity of these street houses, whether or not the street houses are still safe enough, or they should be retrofitted or even demolished. One of the methods to check the seismic performance of corroded RC street houses is by doing seismic evaluation. However, many engineers find it difficult to do seismic evaluation with corrosion consideration. In this research, these two major problems were tried to be solved by applying corrosion effect into USFM (Uniaxial Shear-Flexure Model) approach and by producing a Plastic Hinge Generator program which can generate plastic hinge properties with corrosion consideration. The effect of corrosion was modeled by modifying the properties of steel rebar and cracked concrete. A corroded low-rise RC street houses in Taichung, Taiwan was used to be a case study in this research. The evaluation method was implemented in ETABS Nonlinear version by performing pushover analysis for six cases of service time: 0 year, 10 years, 20 years, 30 years, 40 years, and 50 years. Pushover result showed that the strength reduction is only 13.65% until 50 years of service time. The displacement even increased until 20 years of service time. Otherwise, from 20 years to 50 years of service time, the displacement started to decrease. This unexpected behavior of ultimate displacement was because of the assumption of 20% drops from peak strength and the failure mode of RC members. Those reasons led to inaccuracy of ultimate displacement point determination. The observation of the collapse PGA over all cases of service time showed that the collapse PGAs are larger than the demand PGA in Taichung, Taiwan. It meant that the RC street houses are sufficient enough to sustain the seismic loading even until 50 years of service time. The reduction rate of collapse PGA for RC street houses in this case study is 1.14% - 2.14% per 10 years.
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Bastidas-Arteaga, Emilio. "Probabilistic service life modeling of RC structures subjected to the combined effect of chloride-induced corrosion and cyclic loading." Phd thesis, 2009. http://tel.archives-ouvertes.fr/tel-01065817.
Full textAbstract:
Durability of reinforced concrete (RC) structures placed in non-aggressive environments is often sat- isfactory. However, under certain environmental conditions there are internal or external actions that significantly reduce their lifetime. Nowadays, lifetime assessment of deteriorating structures is focused on the isolated effect of the main deterioration processes (corrosion, fatigue, creep, etc.). However, it is paramount to study the combined effect of various deterioration processes because such interaction could reduce structural integrity. This study proposes a new model for lifetime assessment of RC structures subjected to corrosion- fatigue deterioration processes. The proposed model distinguishes between the following phenomena: chloride penetration, corrosion of reinforcement, concrete cracking and corrosion-fatigue of reinforcing bars. Chloride penetration determines corrosion initiation. Corrosion reduces the cross-section of reinforcing steel. The accumulation of corrosion products in the steel/concrete interface produces concrete cracking. Fatigue causes the nucleation and the propagation of cracks in steel bars. The interaction between corrosion and fatigue can only be taken into account when modeling the combined problem. Thus, pitting corrosion generates stress concentrations that nucleate cracks in the reinforcing bars. Cyclic loading and environmental factors affect the kinematics of crack propagation. There exists significant uncertainty related to the combined corrosion-fatigue problem. This study also addresses this problem by considering the uncertainty inherent in (1) material properties, (2) model and its parameter and (3) environmental actions. Time-invariant random variables represent the uncertainty of material properties and model. Stochastic processes consider the uncertainty of environmental actions. The proposed stochastic models for weather (temperature and humidity) take into account seasonal variations and global warming. The stochastic models for environmental chloride concentration differentiate between exposure to de-icing salts or the sea. Finally, a fuzzy approach accounts for the uncertainty related to corrosion rate. The proposed model is applied to the reliability analysis of RC members located in various chloride- contaminated environments. Overall results reveal that the combined effect of corrosion-fatigue de- pends on environmental conditions and strongly influences the performance of RC structures leading to large reductions in expected lifetime.