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Title: Volumetric changes of cement paste under exposure to the simulated corrosion products of steel and their influence on cracking susceptibility.
Creator: Bedu, Philippe., Florida Atlantic University, Hartt, William H.
Abstract/Description: Dimensional changes of thin cement paste specimens were monitored during exposure to distilled water, hydrochloric acid, alkaline and FeCl$\sb2$ solutions; and comparison was made with the experimental results obtained by other authors. Post experimental examination of reaction products formed on the specimen surface exposed to FeCl$\sb2$ was conducted using X-Ray diffraction. The data resulting from the measured dimensional changes were input to a finite element model to project the stresses...
Show moreDimensional changes of thin cement paste specimens were monitored during exposure to distilled water, hydrochloric acid, alkaline and FeCl$\sb2$ solutions; and comparison was made with the experimental results obtained by other authors. Post experimental examination of reaction products formed on the specimen surface exposed to FeCl$\sb2$ was conducted using X-Ray diffraction. The data resulting from the measured dimensional changes were input to a finite element model to project the stresses that should occur in association with localized corrosion of embedded steel and wetting of adjacent cement by aqueous FeCl$\sb2$. Implications of the findings with regard to cement and concrete cracking in association with embedded metal corrosion are discussed.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14990
Subject Headings: Reinforced concrete--Corrosion, Reinforced concrete--Cracking, Steel--Corrosion, Volumetric analysis
Format: Document (PDF)

Title: Thickness and weld profile effects upon the fatigue crack development in sea water.
Creator: Li, Yong., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This research investigated the plate thickness and weld profile effects upon fatigue of structural steel in sea water. Specific attention was focused on the initiation and propagation behavior of fatigue cracks formed at the toe of different profiled welds and varied plate thicknesses. It was shown that the initiation life was reduced as the thickness increased. The improved weld profile increased the crack initiation life. Analysis of the fatigue data indicated that the Initiation Life to...
Show moreThis research investigated the plate thickness and weld profile effects upon fatigue of structural steel in sea water. Specific attention was focused on the initiation and propagation behavior of fatigue cracks formed at the toe of different profiled welds and varied plate thicknesses. It was shown that the initiation life was reduced as the thickness increased. The improved weld profile increased the crack initiation life. Analysis of the fatigue data indicated that the Initiation Life to Failure Life Ratio Ni/Nf appeared to be greater for the improved weld profile than for the AWS Basic weld profile. The improved weld profile prolonged the propagation life Np. The thickness factor influenced the propagation life Np for the improved weld profile, but the trend was uncertain for the basic weld profile.
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Date Issued: 1989
PURL: http://purl.flvc.org/fcla/dt/14532
Subject Headings: Steel, Structural--Fatigue
Format: Document (PDF)

Title: Thermodynamic analysis of the influences of temperature and pressure on deep sea cathodic protection criterion.
Creator: Wang, Weiqing., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Knowledge of the reversible potential for corrosion reaction under condition of deep sea exposure and how this is influenced by parameters such as temperature and pressure is of importance to the understanding and design of deep sea cathodic protection systems, since this potential is used as the cathodic protection criterion. Also, if the polarized potential is more negative than the reversible potential of the hydrogen reaction, then hydrogen embrittlement may occur. Thermodynamic analysis...
Show moreKnowledge of the reversible potential for corrosion reaction under condition of deep sea exposure and how this is influenced by parameters such as temperature and pressure is of importance to the understanding and design of deep sea cathodic protection systems, since this potential is used as the cathodic protection criterion. Also, if the polarized potential is more negative than the reversible potential of the hydrogen reaction, then hydrogen embrittlement may occur. Thermodynamic analysis methods are used to calculate Gibbs free energy change and reversible potential of reactions involved in cathodic protection of steel for temperatures and pressures typical of deep sea. Based on the assumptions employed it is found that the reversible potential for the iron reaction becomes less negative with depth for the first 1000m and remains approximately constant beyond this.
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Date Issued: 1989
PURL: http://purl.flvc.org/fcla/dt/14515
Subject Headings: Steel--Cathodic protection, Seawater--Thermodynamics
Format: Document (PDF)

Title: STUDY OF THE WIDE-BAND SPECTRUM FATIGUE ON WELDED OFFSHORE STRUCTURES.
Creator: CHU, ZIN-HON., Florida Atlantic University, Hartt, William H.
Abstract/Description: In the present research butt welded ABS DH-32 steel specimens were fatigue tested under freely corroding and cathodic protection conditions by a time-series simulated wide-band spectra of a North Sea wave climate. Previous research pertaining to the probabilistic features of wave dynamics, wave force models, Markov-Chain sea state evolution and time-series simulation of wide-band spectra are addressed as a background review. The resulting freely corroding data are discussed on the basis of...
Show moreIn the present research butt welded ABS DH-32 steel specimens were fatigue tested under freely corroding and cathodic protection conditions by a time-series simulated wide-band spectra of a North Sea wave climate. Previous research pertaining to the probabilistic features of wave dynamics, wave force models, Markov-Chain sea state evolution and time-series simulation of wide-band spectra are addressed as a background review. The resulting freely corroding data are discussed on the basis of the SN plot which developed from the previous investigations at FAU. Calculation of the damage of failed specimens by employing the "Equivalent Narrow-Band Approach" resulted in excellent agreement with the linear damage summation assumption.
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Date Issued: 1985
PURL: http://purl.flvc.org/fcla/dt/14266
Subject Headings: Steel--Fatigue, Steel--Corrosion
Format: Document (PDF)

Title: A STUDY OF STRESS CORROSION CRACKING IN 7079-T651 ALUMINUM.
Creator: FINNEGAN, JOHN EDMUND., Florida Atlantic University, Hartt, William H.
Abstract/Description: This study investigated the stress corrosion cracking behavior of aluminum alloy 7079 - T651 in two corrosive environments, sea water and a 3% NaCl-distilled water solution. Self stressing, double cantilever beam specimens were employed; and these were stressed at various levels, exposed in one of the two test environments and crack extension monitored as a function of time. Equations for the plane strain stress intensity factor (K1) were compared and evaluated, with respect to stress...
Show moreThis study investigated the stress corrosion cracking behavior of aluminum alloy 7079 - T651 in two corrosive environments, sea water and a 3% NaCl-distilled water solution. Self stressing, double cantilever beam specimens were employed; and these were stressed at various levels, exposed in one of the two test environments and crack extension monitored as a function of time. Equations for the plane strain stress intensity factor (K1) were compared and evaluated, with respect to stress intensities calculated from compliance measurements. Results suggest that stress intensity is not the only important variable controlling crack growth rate and a time dependent cracking mechanism may govern a portion of crack growth.
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Date Issued: 1975
PURL: http://purl.flvc.org/fcla/dt/13730
Subject Headings: Aluminum--Corrosion, Stress corrosion
Format: Document (PDF)

Title: STUDY OF ELECTROCHEMISTRY MODIFICATIONS WITHIN CATHODICALLY PROTECTED FATIGUE CREVICES IN 3% SODIUM-CHLORIDE - DISTILLED WATER SOLUTION AND SEAWATER.
Creator: RAJPATHAK, SHIRISH SHRIDHAR., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: It is well recognized that the electrochemistry modifications within cathodically protected fatigue crevices in seawater has pronounced effect on crack growth rate. This study focuses its attention on potential distribution within simulated fatigue crevice as a function of electrolyte velocity, fatigue frequency and cathodic protection potential. Results of salt water electrolyte and seawater electrolyte are compared to bring about the effect of calcareous deposits, Finally, a mathematical...
Show moreIt is well recognized that the electrochemistry modifications within cathodically protected fatigue crevices in seawater has pronounced effect on crack growth rate. This study focuses its attention on potential distribution within simulated fatigue crevice as a function of electrolyte velocity, fatigue frequency and cathodic protection potential. Results of salt water electrolyte and seawater electrolyte are compared to bring about the effect of calcareous deposits, Finally, a mathematical model based on mass transfer laws is developed to rationalise potential distribution trends within fatigue crevice and are compared with the observed behaviour.
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Date Issued: 1983
PURL: http://purl.flvc.org/fcla/dt/14151
Subject Headings: Cathodic protection, Metals--Corrosion fatigue, Sea-water corrosion
Format: Document (PDF)

Title: Study of corrosion-induced failure mechanisms of epoxy-coated reinforcing steel.
Creator: Lee, Seung-Kyoung, Florida Atlantic University, Hartt, William H., McIntyre, Jack F., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A study of the corrosion protection afforded by epoxy coatings on reinforcing steel was performed. To accomplish this bars were acquired from ten sources and coatings were characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in various aqueous solutions at both ambient temperature and 80$\sp\circ$C and in chloride-contaminated concrete slabs under outdoor exposure. Direct pull-off adhesion testing was performed on tested and...
Show moreA study of the corrosion protection afforded by epoxy coatings on reinforcing steel was performed. To accomplish this bars were acquired from ten sources and coatings were characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in various aqueous solutions at both ambient temperature and 80$\sp\circ$C and in chloride-contaminated concrete slabs under outdoor exposure. Direct pull-off adhesion testing was performed on tested and virgin epoxy coated reinforcing steels (ECRs). Electrochemical impedance spectroscopy (EIS) scans were made periodically, and a curve fitting technique was employed to analyze coating parameters. Conventional electrochemical measurements were also made, and corrosion morphology of ECR specimens was examined. It was found that the density and size of coating defects was the primary factor affecting ECR performance. The circuit analysis indicated that poorly performing defect-free coatings absorbed water and oxygen; and these species reached the coating/substrate interface and electrochemical reactions at the interface caused coating degradation. By way of contrast, the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here also. Experimental results indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects developed during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/12389
Subject Headings: Corrosion and anti-corrosives, Epoxy coatings, Steel--Corrosion, Concrete--Corrosion
Format: Document (PDF)

Title: STRESS CORROSION CRACKING OF 7079-T651 ALUMINUM IN RESPONSE TO A CONSTANT STRESS INTENSITY.
Creator: SCOTT, DARWIN HAROLD, II., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Double cantilever beam specimens of 7079-T651 aluminum were subjected to low constant stress intensities in a sea water environment to determine the stress corrosion cracking response. In addition to a constant stress intensity some specimens were subjected to controlled, constant potentials. Despite the fact that all tests were in Region I of the crack growth rate-stress intensity curve, where the former has been projected to be very dependent upon the latter, a unique relationship between...
Show moreDouble cantilever beam specimens of 7079-T651 aluminum were subjected to low constant stress intensities in a sea water environment to determine the stress corrosion cracking response. In addition to a constant stress intensity some specimens were subjected to controlled, constant potentials. Despite the fact that all tests were in Region I of the crack growth rate-stress intensity curve, where the former has been projected to be very dependent upon the latter, a unique relationship between stress intensity and crack growth rate was not always indicated. Therefore, some variable other than stress intensity is assumed to control crack growth, particularly for the first several hundred hours of exposure. The observed behavior is discussed in terms of accepted theories of stress corrosion cracking in high strength aluminum alloys, including electrochemical dissolution and hydrogen embrittlement.
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Date Issued: 1977
PURL: http://purl.flvc.org/fcla/dt/13878
Subject Headings: Stress corrosion, Aluminum--Corrosion
Format: Document (PDF)

Title: A STRESS CONCENTRATION ANALYSIS OF SELECTED WELDS FROM FATIGUE SPECIMENS USING THE FINITE-ELEMENT METHOD.
Creator: NEROLICH, SHAUN MICHAEL., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The stress concentration which exists at the toe of an AWS class 'c' weld has been investigated by means of the finite element method. This type of weld is representative of that specified to join tubular members for offshore structures. Welded fatigue specimens were sectioned and the weld profile described in terms of 1) the weld toe radius (R), 2) the reinforcement angle (e) and 3) the filler metal height QH). A statistical analysis was performed to determine the correlation between R, e...
Show moreThe stress concentration which exists at the toe of an AWS class 'c' weld has been investigated by means of the finite element method. This type of weld is representative of that specified to join tubular members for offshore structures. Welded fatigue specimens were sectioned and the weld profile described in terms of 1) the weld toe radius (R), 2) the reinforcement angle (e) and 3) the filler metal height QH). A statistical analysis was performed to determine the correlation between R, e and H from which it was found that they are independent of each other. By use of the finite element method, trends were established for the effect each parameter has on the stress concentration at the weld toe. Analysis of the effect of undercutting was also perfonned and the results used to offer an explanation why fatigue cracks propagate to failure in some cases and arrest in others.
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Date Issued: 1981
PURL: http://purl.flvc.org/fcla/dt/14069
Subject Headings: Offshore structures--Welding, Welded joints--Fatigue
Format: Document (PDF)

Title: Steel cathodic polarization and calcareous deposit characteristics in deep seawater.
Creator: Chen, Shaowei., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Field and laboratory ambient and simulated deep seawater sacrificial anode cathodic protection experiments were performed by coupling steel specimens to Al-Zn-Hg anode through an appropriately sized external resistor and thereby permitting a particular level of cathodic protection from freely corroding to overprotection to be simulated. The effects of sea current velocity, surface preparation, initial current density, temperature and hydrostatic pressure upon cathodic polarization and...
Show moreField and laboratory ambient and simulated deep seawater sacrificial anode cathodic protection experiments were performed by coupling steel specimens to Al-Zn-Hg anode through an appropriately sized external resistor and thereby permitting a particular level of cathodic protection from freely corroding to overprotection to be simulated. The effects of sea current velocity, surface preparation, initial current density, temperature and hydrostatic pressure upon cathodic polarization and characteristics of calcareous deposits were investigated in the context of slope parameter and steady-state potential and current density trend. The results revealed that a linear relationship between cathode potential and current density is applicable for design of sacrificial anode cathodic protection systems and analysis of cathodic protection survey data from existing structures both in shallow and deep waters. It was also found that for cathodically polarized steel specimens in ambient (shallow) seawater steady-state cathode potential and current density varied according to a sigmoidal trend that indicates the importance of calcareous deposits in such exposures and demonstrated the utility of rapid polarization. On the other hand, no sigmoidal trend was apparent for field and simulated deep water tests; but instead steady-state current density was constant for potential range between -0.80 and -1.05 v (Ag/AgCl). This disclosed that no particular benefit could be derived from employing rapid polarization in cold water exposures. SEM, EDX and X-ray diffraction analysis revealed that the calcareous deposits formed upon specimens exposed at 5C and ambient pressure or 8.96 MPa laboratory experiments exhibited two layer structures--an outer layer of CaCO3 as aragonite and inner layer of Mg(OH)2 as brucite. The morphology and coverage of the deposits depended on the design slope parameter (initial current density). Field testing results indicated that deposits were also composed of CaCO3 and Mg(OH)2 where the former was calcite. Because of the poor coverage of the deposits formed in the deep water condition, limited current density reduction was noted. These results suggest that a different cp design approach and strategy should be considered for deep, cold seawater compared to that commonly used in shallow water environments.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/12457
Subject Headings: Seawater corrosion, Cathodic protection, Steel--Corrosion
Format: Document (PDF)

Title: SPECTRUM FATIGUE ON WELDED STRUCTURAL STEEL UNDER CORROSION AND CATHODIC PROTECTION CONDITIONS.
Creator: YANG, JOE-MING., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The object of this work was to investigate the fatigue performance of 25.4mm thick, butt welded ABS DH-32 steel plate under spectrum loading, which simulated the environmental conditions of the North Sea. Specimens were tested in sea water under different levels of cathodic protection. The results, including the previous freely corroding data, are discussed with regard to the effect of cyclic - frequency, loading history, weld profile and cathodic protection. This study indicated that load...
Show moreThe object of this work was to investigate the fatigue performance of 25.4mm thick, butt welded ABS DH-32 steel plate under spectrum loading, which simulated the environmental conditions of the North Sea. Specimens were tested in sea water under different levels of cathodic protection. The results, including the previous freely corroding data, are discussed with regard to the effect of cyclic - frequency, loading history, weld profile and cathodic protection. This study indicated that load interaction effects are negligible in the present experiments. However, frequency, weld geometry and cathodic protection significantly effect fatigue life.
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Date Issued: 1984
PURL: http://purl.flvc.org/fcla/dt/14207
Subject Headings: Steel, Structural--Fatigue, Steel, Structural--Testing
Format: Document (PDF)

Title: Spectrum fatigue of welded structural steel in sea water.
Creator: Clark, A. M., Qian, D., Hartt, William H., Martin, P. E., Czarnecki, M. F., Harbor Branch Oceanographic Institute
Date Issued: 1983
PURL: http://purl.flvc.org/fau/fd/FA00007432
Subject Headings: Offshore structures--Welded joints--Fatigue, Steel, Structural--Fatigue, Seawater
Format: Document (PDF)

Title: SIMULATED NORTH SEA SPECTRUM FATIGUE ON WELDED STEEL IN FLOWING SEA WATER.
Creator: Clark, A. M., Florida Atlantic University, Hartt, William H.
Abstract/Description: Reverse bend, uniform stress beam specimens of ABS DH-32 steel were subjected to fatigue cycles of randomly generated amplitude in a sea water environment to determine the effect of narrow band spectrum loading on cycles to failure. The loading spectrum was the C/12/20 spectrum, developed at the National Engineering Laboratory in Scotland to simulate the severe conditions of the North Sea. Some misinformation which has been published by NEL and other& regarding ~he C/12/20 spectrum is...
Show moreReverse bend, uniform stress beam specimens of ABS DH-32 steel were subjected to fatigue cycles of randomly generated amplitude in a sea water environment to determine the effect of narrow band spectrum loading on cycles to failure. The loading spectrum was the C/12/20 spectrum, developed at the National Engineering Laboratory in Scotland to simulate the severe conditions of the North Sea. Some misinformation which has been published by NEL and other& regarding ~he C/12/20 spectrum is addressed. A number ot means for presenting random amplitude cycles to failure data in the form of an SN plot are discussed. A means for taking into account fatigue test cycling rate in failure predictions is proposed, and the results of the freely corroding specimens of this investigation conform to the proposed technique. The random amplitude specimens exhibited reduced fatigue lives compared with similar specimens of an earlier constant amplitude investigation.
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Date Issued: 1983
PURL: http://purl.flvc.org/fcla/dt/14153
Subject Headings: Steel--Fatigue, Steel--Stress corrosion
Format: Document (PDF)

Title: Silicone (RTV) sealant bonded aluminum joints: An experimental study.
Creator: Antony, Melvin., Florida Atlantic University, Hartt, William H.
Abstract/Description: The performance of adhesively bonded joints in terms of strength, sealing capacity and environmental resistance is of concern to designers in many fields including the marine industry. In the present work floating roller peel tests were utilized to study the bond properties of aluminum-silicone (RTV) joints. An attempt was made to identify the factors that affect the joint strength. Experiments revealed that peel strength increased with sealant thickness and decreased at high peel rates....
Show moreThe performance of adhesively bonded joints in terms of strength, sealing capacity and environmental resistance is of concern to designers in many fields including the marine industry. In the present work floating roller peel tests were utilized to study the bond properties of aluminum-silicone (RTV) joints. An attempt was made to identify the factors that affect the joint strength. Experiments revealed that peel strength increased with sealant thickness and decreased at high peel rates. Organo-silane primer SS4044 was found to improve the weatherability and strength of the joint. Results point out that mechanical interlocking combined with chemical alteration of the substrate surface was responsible for this improved adhesion. Combinations of three different environmental parameters were studied, and it was shown that seawater was the most hostile single type and a combined exposure to seawater and UV radiation (to simulate a marine environment) proved to be the worst overall. Tests showed that relaxation was governed by sealant thickness alone and was not affected by the marine environment.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14711
Subject Headings: Aluminum--Bonding, Sealing compounds, Strength of materials
Format: Document (PDF)

Title: The role of polyethylene duct cracking in the failure of post-tensioned cables in Florida segmental bridges.
Creator: David, Florent Martin., Florida Atlantic University, Hartt, William H.
Abstract/Description: During the past several decades, segmental construction using precast sections has evolved as a preferred design and construction method for bridges. The tendons used to hold the precast sections together are comprised of cables surrounded by a plastic duct filled with grout. Cracking of the tendon's protective plastic duct has been observed in several Florida bridges. An experimental investigation was performed to characterize the material properties of the high density polyethylene ducts...
Show moreDuring the past several decades, segmental construction using precast sections has evolved as a preferred design and construction method for bridges. The tendons used to hold the precast sections together are comprised of cables surrounded by a plastic duct filled with grout. Cracking of the tendon's protective plastic duct has been observed in several Florida bridges. An experimental investigation was performed to characterize the material properties of the high density polyethylene ducts used in the past and those being specified nowadays. The degree of cure of the resin, the results of three-point bending tests for unnotched and notched specimens, the coefficient of thermal expansion, and the deformation of a tendon as a function of temperature changes were studied. The effects of the grouting pressure and the void presence in the grout were quantified and the pressurization period was shown to affect significantly the pipe strain.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/12999
Subject Headings: Pipe, Plastic--Testing, Bridges--Florida, Post-tensioned prestressed concrete construction
Format: Document (PDF)

Title: The role of calcium-hydroxide in the maintenance of passivity of steel.
Creator: Sohanghpurwala, Ali Akbar S., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The objective of this study was to determine whether the presence of undissolved calcium hydroxide at the steel interface helped maintain or delay the breakdown of passivity under adverse conditions, such as the presence of chlorides and carbonation. Saturated calcium hydroxide solution was used as an electrolyte in the test cell, and steel specimens were exposed to a range of chloride ion concentration and carbonation. The results indicate that undissolved calcium hydroxide has an important...
Show moreThe objective of this study was to determine whether the presence of undissolved calcium hydroxide at the steel interface helped maintain or delay the breakdown of passivity under adverse conditions, such as the presence of chlorides and carbonation. Saturated calcium hydroxide solution was used as an electrolyte in the test cell, and steel specimens were exposed to a range of chloride ion concentration and carbonation. The results indicate that undissolved calcium hydroxide has an important role in the passivation of reinforcing steel. Also, the critical chloride to hydroxide ratio may be more relevant in characterizing the breakdown of passivity than the threshold value of total or soluble chloride present in the electrolyte. It was noted that in the presence of undissolved calcium hydroxide, steel remained passive for as high a chloride ion concentration as 0.54% (by weight of electrolyte).
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14429
Subject Headings: Chlorides, Steel--Corrosion
Format: Document (PDF)

Title: RESPONSE OF 1018 STEEL TO CONCURRENT CYCLIC LOADING AND CATHODIC POLARIZATION IN NATURAL SEA WATER.
Creator: HOOPER, WILLIAM CLARENCE., Florida Atlantic University, Hartt, William H.
Abstract/Description: Reverse bend, constant deflection fatigue experiments were conducted in natural sea water at 1850 cycles per minute (cpm) to investigate the response of 1018 notched steel to concurrent cyclic loading and cathodic polarization. For comparison purposes S-log N curves were also determined in air and high purity argon. These indicate that the endurance limit established in sea water by cathodic polarization at -0.85 volts, Saturated Calomel Electrode (SCE), is greater than in either air or argon...
Show moreReverse bend, constant deflection fatigue experiments were conducted in natural sea water at 1850 cycles per minute (cpm) to investigate the response of 1018 notched steel to concurrent cyclic loading and cathodic polarization. For comparison purposes S-log N curves were also determined in air and high purity argon. These indicate that the endurance limit established in sea water by cathodic polarization at -0.85 volts, Saturated Calomel Electrode (SCE), is greater than in either air or argon. Two mechanisms are considered as responsible for this behavior. 1. Presence of carbonate and hydroxide deposits coupled with increased alkalinity at non-propagating crack tips. 2. Adsorbed OH- layer at non-propagating crack tips.
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Date Issued: 1976
PURL: http://purl.flvc.org/fcla/dt/13781
Subject Headings: Steel--Testing
Format: Document (PDF)

Title: Prestressing steel to concrete bond degradation due to cathodic polarization.
Creator: Joubert, Emmanuel., Florida Atlantic University, Hartt, William H.
Abstract/Description: Experiments were conducted to evaluate occurrence of any deterioration of prestressing steel tendon to concrete bond as a consequence of cathodic polarization. Pretensionned concrete specimens were cathodically polarized with current densities ranging from 50 to 5000 m^2 of steel while exposed to a constant flow of natural sea water. The concrete and steel dimensional changes were monitored by strain gages mounted on the tendons and embedded in the concrete. Contractions of the steel of 25 to...
Show moreExperiments were conducted to evaluate occurrence of any deterioration of prestressing steel tendon to concrete bond as a consequence of cathodic polarization. Pretensionned concrete specimens were cathodically polarized with current densities ranging from 50 to 5000 m^2 of steel while exposed to a constant flow of natural sea water. The concrete and steel dimensional changes were monitored by strain gages mounted on the tendons and embedded in the concrete. Contractions of the steel of 25 to 50 percent of the initial tensioning were recorded after 17 to 36 MC/m^2 were transferred to the tendons on specimens polarized at the highest currents. This corresponds to 54 to 114 years of polarization at 10mA/m^2 if bond loss was solely dependent on the charge transfer. It was noticed that the smaller the current, the more the charge that was transferred before steel contraction began. These results imply that cathodic polarization should impose no threat to the prestressing steel-to-concrete bond on typical structures over their expected lifetime.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15209
Subject Headings: Prestressed concrete, Steel--Corrosion, Cathodic protection
Format: Document (PDF)

Title: Potential attenuation and anode current output determination alternatives for galvanic anode cathodic protection upon offshore pipelines.
Creator: Bethune, Keith P., Florida Atlantic University, Hartt, William H.
Abstract/Description: A recently developed equation governing cathodic polarization attenuation along a pipeline protected by galvanic anodes is first solved. The solution is based upon a numerical finite difference method (FDM). The resulting subroutine computes the polarization along the cathode and the corresponding anode current output based upon the physical design variables and electrochemical properties of the cathode. Validation of this method is accomplished through comparisons with a proven existing...
Show moreA recently developed equation governing cathodic polarization attenuation along a pipeline protected by galvanic anodes is first solved. The solution is based upon a numerical finite difference method (FDM). The resulting subroutine computes the polarization along the cathode and the corresponding anode current output based upon the physical design variables and electrochemical properties of the cathode. Validation of this method is accomplished through comparisons with a proven existing method for attenuation prediction, namely the Boundary Element Method (BEM). As both the FDM and BEM solutions are mathematically complex and time consuming, it is then demonstrated that a modified form of Ohm's Law that quantitatively interrelates (1) design life, (2) anode size, weight, and properties, (3) pipe size, current demand, and coating quality, (4) sea water resistivity, (5) magnitude of polarization, and (6) anode spacing is sufficient for design purposes where metallic resistance of the pipeline itself is negligible. This new method can be easily adapted in a spreadsheet type analysis as no numerical subroutine is necessary. One size pipeline of varying lengths is analyzed using these methods for comparisons and validation and the effect of metallic resistance on attenuation profiles is examined. It is concluded that for small diameter pipelines with anode spacing up to 800 m metallic resistance is negligible, and thus all three methods can be used with reasonable confidence for spacings below 800 m. An analysis to illustrate the effect of a stratified electrolyte in the vicinity of the pipeline has been initiated and preliminary results are also presented.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/12672
Subject Headings: Underwater pipelines, Pipelines--Cathodic protection
Format: Document (PDF)

Title: Polyethylene duct cracking in post-tensioning tendons of Florida segmental bridges.
Creator: Suarez, Jorge Alejandro, Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: For the purpose of investigating the cause of duct cracking in post-tensioning tendons and improving the durability of this type of structure, a series of experiments was performed. These were divided in two groups, the first to simulate the state of stress inside the tendon ducts and the second to compare the properties of new materials approved according to new regulations on the subject and those used in the construction of the structures. A proposed mechanism of cracking was studied and...
Show moreFor the purpose of investigating the cause of duct cracking in post-tensioning tendons and improving the durability of this type of structure, a series of experiments was performed. These were divided in two groups, the first to simulate the state of stress inside the tendon ducts and the second to compare the properties of new materials approved according to new regulations on the subject and those used in the construction of the structures. A proposed mechanism of cracking was studied and its validity verified. According to simulations performed on specimens that were fabricated and others developed by the finite element method, new major factors were found to explain the duct failure. Finally, a comparison of mechanical properties indicated a difference between virgin and aged materials.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13071
Subject Headings: Post-tensioned prestressed concrete construction, Bridges--Florida, Polyethylene
Format: Document (PDF)

FAU Theses and Dissertations (80)	+ -
HBOI Faculty Contributions (1)	+ -
Florida Atlantic University Patents (1)	+ -

Steel--Corrosion (19)	+ -
Cathodic protection (15)	+ -
Steel--Fatigue (9)	+ -
Corrosion and anti-corrosives (8)	+ -
Reinforced concrete--Corrosion (8)	+ -

Chlorides (6)	+ -
Sea-water corrosion (6)	+ -
Seawater corrosion (6)	+ -
Offshore structures (4)	+ -
Pipelines--Cathodic protection (4)	+ -
Seawater (4)	+ -
Steel--Cathodic protection (4)	+ -
Underwater pipelines (4)	+ -
Aluminum--Corrosion (3)	+ -
Concrete--Corrosion (3)	+ -
Prestressed steel construction (3)	+ -
Reinforced concrete construction--Corrosion (3)	+ -
Reinforcing bars--Corrosion (3)	+ -
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