Current Search: info:fedora/islandora:personCModel (x) » info:fedora/fau:CurrentETDs (x) » English (x) » Hartt, William H. (x)
View All Items
Pages
- Title
- Adhesion of calcareous deposits formed on steel surfaces under cathodic polarization.
- Creator
- Luo, Jiunn-Shyong, Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A procedure has been devised to characterize the adhesion of calcareous deposits formed upon steel in association with cathodic polarization in seawater. This involved bending the substrate in-situ and characterization of deposit debonding in terms of visual appearance, changes in the cathodic current density and the net charge transferred in association with film disruption. Specific attention has been focused upon the influence of exposure time, applied potential, flow rate, temperature,...
Show moreA procedure has been devised to characterize the adhesion of calcareous deposits formed upon steel in association with cathodic polarization in seawater. This involved bending the substrate in-situ and characterization of deposit debonding in terms of visual appearance, changes in the cathodic current density and the net charge transferred in association with film disruption. Specific attention has been focused upon the influence of exposure time, applied potential, flow rate, temperature, substrate surface finish and electrolyte type upon deposit adhesion. Presence of a Mg-rich, inner film as well as the impingement of CaCO3 particles enhanced the adhesion of calcareous deposits. Electrostatic forces, Van der Waals attraction, and chemical alteration of precipitates could be important factors contributing to deposit adhesion.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/12271
- Subject Headings
- Sea-water corrosion, Marine steel, Cathodic protection, Adhesives
- Format
- Document (PDF)
- Title
- APPLICABILITY OF CATHODIC PROTECTION IN PREVENTION OF CORROSION DAMAGE TO STEEL TENDONS IN PRESTRESSED CONCRETE (HIGH STRENGTH STEEL, HYDROGEN EMBRITTLEMENT, BRITTLE CRACKING).
- Creator
- SCANNELL, WILLIAM THOMAS., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A series of experiments were performed on a single tendon in a prestressed concrete slab for the purpose of studying the susceptibility of the high strength steel to brittle fracture as a result of cathodic protection. The procedure first involved impressing an anodic current until active potentials were recorded along the tendon length. Subsequently, cathodic polarization of the midsection of the tendon to -1.3 V(SCE) was effected. After a prescribed time, the tendon was removed and...
Show moreA series of experiments were performed on a single tendon in a prestressed concrete slab for the purpose of studying the susceptibility of the high strength steel to brittle fracture as a result of cathodic protection. The procedure first involved impressing an anodic current until active potentials were recorded along the tendon length. Subsequently, cathodic polarization of the midsection of the tendon to -1.3 V(SCE) was effected. After a prescribed time, the tendon was removed and sectioned into 15 ern lengths. Each segment strand was then notched and strained to failure, in three-point bending, in order to determine any effect of cathodic protection on the mechanical properties of the material. Differences in average failure loads were compared to determine if a loss of load-bearing capacity and brittle fracture occurred due to hydrogen absorption.
Show less - Date Issued
- 1986
- PURL
- http://purl.flvc.org/fcla/dt/14324
- Subject Headings
- Prestressed concrete--Testing, Steel--Corrosion
- Format
- Document (PDF)
- Title
- The assessment of bond for cathodically polarized pretensioning steel in concrete.
- Creator
- Dohlen, Knut Herman., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
Pretensioned concrete members require a certain bond strength between the steel and concrete to maintain prestress force. Previous studies have indicated that when reinforcing steel in concrete is cathodically polarized, a chemical change of the cement near the steel-concrete interface occurs; and this can reduce the bond strength. In the present research experiments were conducted with concrete specimens that contained either a non-stressed seven wire steel tendon or a single strand through...
Show morePretensioned concrete members require a certain bond strength between the steel and concrete to maintain prestress force. Previous studies have indicated that when reinforcing steel in concrete is cathodically polarized, a chemical change of the cement near the steel-concrete interface occurs; and this can reduce the bond strength. In the present research experiments were conducted with concrete specimens that contained either a non-stressed seven wire steel tendon or a single strand through the longitudinal direction. The specimens were cathodically polarized with current densities ranging between 50 and 2500 mA/m^2 of steel. Upon achieving a pre-determined charge density transfer, the steel was pulled relative to the concrete until the bond was broken. Results indicate that a total charge density transfer of up to 14000 A*h/m^2 of steel, may introduce an average 16 percent decrease in ultimate bond strength. This and other data were evaluated in order to assess if cathodic protection, as utilized for corrosion control, is likely to compromise structural integrity of pretensioned concrete members and structures.
Show less - Date Issued
- 1998
- PURL
- http://purl.flvc.org/fcla/dt/15543
- Subject Headings
- Cathodic protection, Reinforced concrete--Corrosion
- Format
- Document (PDF)
- Title
- Brittle propensity of chromium microalloyed and corroded prestressing steel under cathodic protection.
- Creator
- Stauder, Anne-Laure T., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Qualification criteria for cathodic protection of pre-tensioned tendon wires in concrete were studied with regard to the risks of embrittlement due to chromium microalloying and existing corrosion damage. The selected materials included two microalloyed (with 0.23 and 0.24 w% chromium) and one non-microalloyed, high carbon prestressing steels. The slow strain rate testing technique was used to evaluate the effects of polarization to -0.90 and -1.30 VSCE upon strength and ductility of the...
Show moreQualification criteria for cathodic protection of pre-tensioned tendon wires in concrete were studied with regard to the risks of embrittlement due to chromium microalloying and existing corrosion damage. The selected materials included two microalloyed (with 0.23 and 0.24 w% chromium) and one non-microalloyed, high carbon prestressing steels. The slow strain rate testing technique was used to evaluate the effects of polarization to -0.90 and -1.30 VSCE upon strength and ductility of the steels. Fractographic analysis was performed using scanning electron microscopy. Based upon statistical analysis, an attempt was made to relate the remaining strength of the corroded wire to the extent of corrosion damage for different corrosion morphologies.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/15475
- Subject Headings
- Cathodic protection, Tendons (Prestressed concrete), Steel--Corrosion, Steel--Embrittlement
- Format
- Document (PDF)
- Title
- Cathodic polarization and protection of simulated prestressed concrete pilings in sea water.
- Creator
- Pangrazzi, Richard., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Experiments were conducted to determine the effectiveness of cathodic polarization on simulated concrete piles containing unstressed continuous and segmented tendons exposed to sea water. Conductive rubber was used as anode material. Corrosion of the steel was enhanced by admixturing calcium chloride during concrete pouring. The specimens were cathodically polarized at constant potentials ranging from -0.72 to -1.10 V(sce). Current on and instant off potentials were monitored along the...
Show moreExperiments were conducted to determine the effectiveness of cathodic polarization on simulated concrete piles containing unstressed continuous and segmented tendons exposed to sea water. Conductive rubber was used as anode material. Corrosion of the steel was enhanced by admixturing calcium chloride during concrete pouring. The specimens were cathodically polarized at constant potentials ranging from -0.72 to -1.10 V(sce). Current on and instant off potentials were monitored along the specimen height at different water levels. The four hour potential decay criterion was used to determine if cathodic polarization was effective. Protection was achieved at locations where instant-off potentials were more negative than -0.79 V(sce). Polarization was never obtained above the anode. Also, the possibility of protecting a structure containing discontinuous steel was investigated. The results are discussed within the context of protecting actual marine pilings from corrosion.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14699
- Subject Headings
- Concrete piling--Corrosion, Prestressed concrete--Corrosion, Reinforcing bars--Cathodic protection
- Format
- Document (PDF)
- Title
- Cathodic polarization behavior of mild steel exposed to selected flow velocities and slope parameters in natural seawater.
- Creator
- Hugus, G. Dickson, IV., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
Twenty-four test cells arranged in a pipe flow setup were assembled to investigate the effect of seawater velocity on the polarization behavior of galvanically polarized mild steel. Each 1023 steel pipe specimen of 10.8 em ID was coupled via a current limiting resistor to a mercury activated aluminum anode and exposed to a velocity of either 0.03, 0.09 or 0.30 m/s. The resistors were sized such that polarization was controlled according to one of six slope parameters. Steady state potential...
Show moreTwenty-four test cells arranged in a pipe flow setup were assembled to investigate the effect of seawater velocity on the polarization behavior of galvanically polarized mild steel. Each 1023 steel pipe specimen of 10.8 em ID was coupled via a current limiting resistor to a mercury activated aluminum anode and exposed to a velocity of either 0.03, 0.09 or 0.30 m/s. The resistors were sized such that polarization was controlled according to one of six slope parameters. Steady state potential and maintenance current density values were determined, and a steady state potential vs. current density curve was established for specimens in each velocity. Some specimens experienced a rise in cathode potential and current density after an apparent steady state had been reached. This was probably related to the influence of velocity on the protectiveness of the calcareous deposit. Of the specimens that experienced a rise in steady state potential and current density, a few were later observed to decrease in potential and current density and reach steady state. Steady state current density vs. velocity plots of specimens at steady state potentials of -0.78, -0.88 and -0.98 V showed that current density was directly proportional to velocity as well as relatively insensitive to potential. Ficks' first law was utilized in conjunction with an empirically derived dimensionless correlation that characterizes the behavior between fluid velocity and mass transfer of molecular species from the bulk solution to the cathode surface in turbulent seawater pipe flow. Calcareous deposit porosity constants were calculated and it was surmised that as velocity increased by a factor of three, the porosity of the deposits near 0.78 and -0.89 V increased by multiples of about two on average. Porosity at the above potentials increased with decreasing potential by a factor of a little over two. SEM micrographs were made and EDX analyses were performed on the calcareous deposits of selected specimens.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/15501
- Subject Headings
- Cathodic protection, Seawater corrosion, Marine steel
- Format
- Document (PDF)
- Title
- Cathodic polarization response of simulated prestressed concrete piles exposed to natural sea water.
- Creator
- Chaix, Olivier., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
Experiments were conducted to determine the effectiveness of localized cathodic polarization for reducing corrosion of simulated prestressed concrete piles containing admixed calcium chloride and exposed to a simulated sea water tidal cycle. The specimens contained both continuous and segmented steel tendons, the purpose of the latter being to facilitate measurement of cathodic protection current. Conductive rubber in an impressed current system was used as the anode material. The specimens...
Show moreExperiments were conducted to determine the effectiveness of localized cathodic polarization for reducing corrosion of simulated prestressed concrete piles containing admixed calcium chloride and exposed to a simulated sea water tidal cycle. The specimens contained both continuous and segmented steel tendons, the purpose of the latter being to facilitate measurement of cathodic protection current. Conductive rubber in an impressed current system was used as the anode material. The specimens were initially freely corroded and then cathodically polarized at a constant current ranging from 0.5 to 1 mA/m$\sp2$ which corresponded to potentials (current-on) which ranged from $-$0.500 to $-$1.100 V(sce) in the anode region. The magnitude of impressed current and its distribution along the embedded steel was monitored as a function of exposure time, level of polarization and water levels. Current-on and instant-off potential distribution for both the continuous and segmented tendons were also measured. The level of cathodic polarization was assessed as a function of position along the specimens by the depolarization method. The results were evaluated within the context of marine bridge substructure cathodic protection technology.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14865
- Subject Headings
- Corrosion and anti-corrosives, Sea-water corrosion, Offshore structures, Reinforced concrete--Deterioration
- Format
- Document (PDF)
- Title
- Cathodic protection modeling of marine pipelines.
- Creator
- Lysogorski, Diane K., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A governing equation for potential attenuation along a pipeline cathodically protected by identical, evenly-spaced, spherical anodes is developed. The numerical solution, obtained using a coordinate based mapping (CoMB) finite difference method (FDM), can be used to predict the potential profile of a pipeline. In addition, a modified version of Ohm's Law is developed to provide an improved approach to design of pipeline CP systems. Both approaches address anode-electrolyte, coating...
Show moreA governing equation for potential attenuation along a pipeline cathodically protected by identical, evenly-spaced, spherical anodes is developed. The numerical solution, obtained using a coordinate based mapping (CoMB) finite difference method (FDM), can be used to predict the potential profile of a pipeline. In addition, a modified version of Ohm's Law is developed to provide an improved approach to design of pipeline CP systems. Both approaches address anode-electrolyte, coating-polarization, and metallic path resistance, but the latter neglects to address the potential gradient associated with the one-dimensional nature of pipelines. These two approaches were compared to results from existing potential prediction methods and Boundary Element Methods (BEM). Furthermore, a procedure was developed to calculate the resistance of rectangular conductor arrays. This procedure was utilized to calculate the resistance of an anode sled. Combination of the first principles based equation and the rectangular array resistance procedure allows one to predict the potential profile for a pipeline protected by identical, evenly-spaced, anode sleds.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12850
- Subject Headings
- Underwater pipelines, Pipelines--Cathodic protection
- Format
- Document (PDF)
- Title
- Characterization of electrochemical properties of arc-sprayed zinc and zinc-aluminum alloy coatings for cathodic protection of reinforced concrete structures.
- Creator
- Sigonney, Yann Manuel., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The present research focused on the behavior of arc sprayed zinc and zinc-aluminum coatings on concrete specimens exposed to specific relative humidity environments (100, 85, 60 and 25% RH) and with specific chloride contents (0.0, 3.0, 5.9 and 11.8 kg/m^3). All specimens experienced a decline in current output with time. Anode wastage and formation of oxidation products were mainly responsible for this lack of protection in 100 and 85% RH, whereas for 60 and 25% RH, drying of the concrete...
Show moreThe present research focused on the behavior of arc sprayed zinc and zinc-aluminum coatings on concrete specimens exposed to specific relative humidity environments (100, 85, 60 and 25% RH) and with specific chloride contents (0.0, 3.0, 5.9 and 11.8 kg/m^3). All specimens experienced a decline in current output with time. Anode wastage and formation of oxidation products were mainly responsible for this lack of protection in 100 and 85% RH, whereas for 60 and 25% RH, drying of the concrete and long-term polarization of the anode were the key factors. Validity of the DC measurements was verified with slope parameter analysis on selected specimens. In addition, Electrochemical Impedance Spectroscopy was performed on the galvanic anode and an equivalent circuit model was obtained for the zinc-concrete interface.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15665
- Subject Headings
- Reinforced concrete--Corrosion, Cathodic protection, Zinc coating
- Format
- Document (PDF)
- Title
- Characterization of environmental cracking of cathodically polarized prestressing steel in a simulated concrete environment.
- Creator
- Narayanan, P. K., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
In order to investigate the environmental cracking tendency of prestressing steel tendons under cathodically polarized conditions, a series of slow strain rate tests were conducted using smooth and notched specimens in simulated concrete porewater environments. Applied potential was varied from -0.500 V to -1.500 V(SCE) at intervals of 0.200 V, and the pH range was 8.0 to 12.5. Based on the test results presented in terms of time-to-failure, reduction in crosssectional area and load at...
Show moreIn order to investigate the environmental cracking tendency of prestressing steel tendons under cathodically polarized conditions, a series of slow strain rate tests were conducted using smooth and notched specimens in simulated concrete porewater environments. Applied potential was varied from -0.500 V to -1.500 V(SCE) at intervals of 0.200 V, and the pH range was 8.0 to 12.5. Based on the test results presented in terms of time-to-failure, reduction in crosssectional area and load at failure, potential regimes for susceptibility to hydrogen embrittlement in saturated Ca(OH)2 solution were identified. SEM analyses performed for both notched and smooth specimens tested at -0.700 V and -1.300 V in saturated Ca(OH)2 solution showed that different fracture mechanisms operate at these two potentials. The cracking processes have been explained based on the test results and SEM analyses. Based upon the data obtained, the steel showed higher resistance to environmental cracking at pH 9.8 and 8.0 than for 12.5. The applicability of the results to cathodic protection of prestressed steel in concrete is discussed.
Show less - Date Issued
- 1988
- PURL
- http://purl.flvc.org/fcla/dt/14472
- Subject Headings
- Steel, High strength--Brittleness
- Format
- Document (PDF)
- Title
- Characterization of steel cathodic polarization in seawater and its applications in offshore structure cathodic protection design.
- Creator
- Wang, Weiqing., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Laboratory experiments have been performed to characterize the effects of initial current density and selected variables (initial current density, temperature and surface treatment) upon the cathodic polarization behavior of API 2H Grade 42 steel in natural sea water. The procedure involved galvanic coupling of a cylindrical steel specimen to a larger diameter aluminum sacrificial anode ring through an external resistor, which offset the otherwise impractically small anode/cathode surface...
Show moreLaboratory experiments have been performed to characterize the effects of initial current density and selected variables (initial current density, temperature and surface treatment) upon the cathodic polarization behavior of API 2H Grade 42 steel in natural sea water. The procedure involved galvanic coupling of a cylindrical steel specimen to a larger diameter aluminum sacrificial anode ring through an external resistor, which offset the otherwise impractically small anode/cathode surface area ratio and permitted the desired initial current density to be realized. In the initial polarization stage the change in potential versus current density data with time was found to be linear with a slope equal to the product of the total circuit resistance and cathode surface area and with the vertical intercept corresponding to the anode open circuit potential. Lower temperature or increased flow resulted in reduced polarization and a relatively high current density, but data for experiments employing a particular resistance conformed to straight lines with the same slope R[ext] x A[c] (external resistance times cathode surface area). Some experiments exhibited concave behavior at longer test duration. An explanation for the linear interdependence of potential and current density and the following concave behavior is presented. The laboratory experiments were compared with offshore structure survey results. It is projected that the potential-current density behavior of galvanic cathodic protection (CP) systems of different geometries can be quantitatively interrelated through this slope parameter. Implications of the data are discussed within the context of cathodic protection design, rapid polarization and system performance for offshore structures.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/12362
- Subject Headings
- Steel--Cathodic protection, Seawater, Offshore structures
- Format
- Document (PDF)
- Title
- CHARACTERIZATION OF THE EMBRITTLEMENT TENDENCY OF A CATHODICALLY POLARIZED SUPERFERRITIC STAINLESS STEEL IN SEAWATER (HYDROGEN DAMAGE, INTERGRANULAR).
- Creator
- KRISHNAMURTHY, RAVI M., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
In order to investigate the cracking tendency of cathodically polarized SEACURE superferritic stainless steel, a series of potentiostatically controlled tests were conducted in flowing natural seawater. U-bend and tensile specimens were used to determine the threshold potential and limiting fracture stress. The microstructure was examined using a metallurgical microscope and a chemical analysis was conducted across the grain boundary. These results were then correlated to hydrogen assisted...
Show moreIn order to investigate the cracking tendency of cathodically polarized SEACURE superferritic stainless steel, a series of potentiostatically controlled tests were conducted in flowing natural seawater. U-bend and tensile specimens were used to determine the threshold potential and limiting fracture stress. The microstructure was examined using a metallurgical microscope and a chemical analysis was conducted across the grain boundary. These results were then correlated to hydrogen assisted cracking, by performing SEM and EDAX analyses on fractured U-bend and tensile samples. Finally a model was developed which explained the predominantly intergranular cracking in the static stress condition and also accommodated the transgranular failure during dynamic loading.
Show less - Date Issued
- 1986
- PURL
- http://purl.flvc.org/fcla/dt/14325
- Subject Headings
- Steel--Fracture, Sea-water corrosion
- Format
- Document (PDF)
- Title
- Chloride thresholds for initiation of corrosion of steel reinforcement in concrete.
- Creator
- Perks, Robert Adam., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A study was performed of variables that affect the chloride threshold for corrosion of reinforcement, including pore water alkalinity, water-to-cement ratio, the use of Florida aggregate, and the addition of fly ash. To accomplish this, specimens were subjected to a periodic wet-dry ponding cycle using 15% by weight NaCl solution. Half cell potential and macrocell current measurements were taken to determine the time to corrosion. Upon active corrosion, the specimens were removed from the...
Show moreA study was performed of variables that affect the chloride threshold for corrosion of reinforcement, including pore water alkalinity, water-to-cement ratio, the use of Florida aggregate, and the addition of fly ash. To accomplish this, specimens were subjected to a periodic wet-dry ponding cycle using 15% by weight NaCl solution. Half cell potential and macrocell current measurements were taken to determine the time to corrosion. Upon active corrosion, the specimens were removed from the ponding cycle and dissected. Powder samples were collected from the concrete at the steel depth to ascertain the total chloride concentration. The determination of the pore water pH was attempted using a leaching method. To date only a portion of the specimens have displayed corrosion. The role of cement alkalinity and water-to-cement ratio in affecting corrosion resistance is reported and the results are discussed within the context of designing concrete structures for corrosion resistance.
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/12721
- Subject Headings
- Steel--Corrosion, Reinforced concrete, Chlorides
- Format
- Document (PDF)
- Title
- CORROSION FATIGUE CRACK INITIATION BEHAVIOR OF SEVERAL HIGH STRENGTH STEELS IN SEAWATER (POTENTIAL, CATHODIC, POLARIZATION).
- Creator
- SLOAN, FORREST EUGENE., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
'J 'ht' c· f feet of seawater ,_tnd potential on the fatigue crack initiation hehavior of several microalloyed and thermomPrhanically processed steels has been investigated. Five steels with yield strength in t~e range 500 to 750 MPa (73 to 108 ksi) were selected which included a range of processing histories from conventional quenching and tempering to precipitation hardening and direct quenching. These steels were chosen because of their potential utility as materials of construction for...
Show more'J 'ht' c· f feet of seawater ,_tnd potential on the fatigue crack initiation hehavior of several microalloyed and thermomPrhanically processed steels has been investigated. Five steels with yield strength in t~e range 500 to 750 MPa (73 to 108 ksi) were selected which included a range of processing histories from conventional quenching and tempering to precipitation hardening and direct quenching. These steels were chosen because of their potential utility as materials of construction for deep water compliant platform hull and riser systems. Blunt notch compact tension specimens were exposed to natural flowing seawater under constant load ampli tnrlc. conditions at both freely corroding and cathodically protected potentials. Cycles to crack initiation were characterized by cyclic stress intensity range normalized relative to the square root of notch radius. Test data are presented and compared with data from other tests and steels using appropriate stress analysis methods.
Show less - Date Issued
- 1986
- PURL
- http://purl.flvc.org/fcla/dt/14285
- Subject Headings
- Steel, High strength--Fatigue--Testing, Sea-water corrosion
- Format
- Document (PDF)
- Title
- CORROSION FATIGUE OF NOTCHED 1018 STEEL IN SEA WATER.
- Creator
- FLUET, JOSEPH E., JR., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
A summary of some pertinent previous research by other authors is presented separately from the actual laboratory report. The report presents the results of air and corrosion fatigue tests which are. interpreted in terms of time to failure, crack growth history, and fracture mechanics techniques. In addition, the results of cathodic protection of corrosion fatigue tests are interpreted in terms of simple-design criteria, as well as relative to Critical Corrosion Rate Theory. One of the more...
Show moreA summary of some pertinent previous research by other authors is presented separately from the actual laboratory report. The report presents the results of air and corrosion fatigue tests which are. interpreted in terms of time to failure, crack growth history, and fracture mechanics techniques. In addition, the results of cathodic protection of corrosion fatigue tests are interpreted in terms of simple-design criteria, as well as relative to Critical Corrosion Rate Theory. One of the more significant results presented is the greater longevity of corrosion fatigue, as compared to air fatigue, notched specimens stressed within 10-15 KSI above the air endurance limit. Also, the potential required to cathodically protect such notched specimens is shown to be 50 mV lower than for comparable smooth specimens. Both phenomena are attributed in part to the lowering of crack pH to acidic levels in notched specimens.
Show less - Date Issued
- 1976
- PURL
- http://purl.flvc.org/fcla/dt/13768
- Subject Headings
- Steel--Fatigue, Steel--Corrosion, Steel--Fracture, Notched bar testing
- Format
- Document (PDF)
- Title
- CORROSION OF CONCRETE COVERED REINFORCING STEEL IN A MARINE ENVIRONMENT RESULTING FROM STRAY CURRENT AND GALVANIC COUPLING.
- Creator
- MILLER, RONALD LAWRENCE., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
It is recognized that reinforced concrete structures are often susceptible to stray current corrosion damage. Experiments have been performed upon a reinforced concrete bridge model in sea water, and these indicate that 0.01 percent of stray direct current in this electrolyte may enter the structure. Alternating current may also contribute to corrosion of reinforcing steel, though experimental results reveal detection to be more difficult than for direct current. Two other sources of current...
Show moreIt is recognized that reinforced concrete structures are often susceptible to stray current corrosion damage. Experiments have been performed upon a reinforced concrete bridge model in sea water, and these indicate that 0.01 percent of stray direct current in this electrolyte may enter the structure. Alternating current may also contribute to corrosion of reinforcing steel, though experimental results reveal detection to be more difficult than for direct current. Two other sources of current in reinforcing steel are from cathodic protection systems of utility attachments and from galvanic coupling of the covered steel and bare steel. Mechanisms by which the above types of current contribute to deterioration of reinforced concrete structures are discussed.
Show less - Date Issued
- 1976
- PURL
- http://purl.flvc.org/fcla/dt/13772
- Subject Headings
- Steel--Corrosion
- Format
- Document (PDF)
- Title
- CORROSION OF STEEL REINFORCEMENT IN CONCRETE: THRESHOLD CHLORIDE ION CONCENTRATION FOR CORROSION IN TYPE I PORTLAND CEMENT CONCRETE.
- Creator
- FUNAHASHI, MIKI., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
Initiation of corrosion of reinforcing steel in concrete is often caused by chlorides. Using a pressurized method for the purpose of accelerating penetration of sea water into concrete, the threshold chloride ion concentration for corrosion of reinforcing steel in Type I portland cement concrete has been studied in detail. The variables that have been investigated include water-cement ratio and steel surface preparation. When corrosion was detected by electrochemical potential measurement,...
Show moreInitiation of corrosion of reinforcing steel in concrete is often caused by chlorides. Using a pressurized method for the purpose of accelerating penetration of sea water into concrete, the threshold chloride ion concentration for corrosion of reinforcing steel in Type I portland cement concrete has been studied in detail. The variables that have been investigated include water-cement ratio and steel surface preparation. When corrosion was detected by electrochemical potential measurement, the test was terminated; and chloride ion concentration was evaluated. No correlation between threshold concentration and water-cement ratio was found. With regard to surface condition, the pre-rusted steel specimen showed a tendency to corrode at a lesser chloride ion concentration than for the other preparation techniques, which were sand blasting and pretreatment in a saturated calcium hydroxide solution. The results are presented and discussed within a perspective of established concrete and corrosion technologies.
Show less - Date Issued
- 1985
- PURL
- http://purl.flvc.org/fcla/dt/14264
- Subject Headings
- Steel--Corrosion, Reinforced concrete
- Format
- Document (PDF)
- Title
- CRACKING OF CONCRETE DUE TO CORROSION OF VARIOUS EMBEDDED METALS.
- Creator
- TURNER, DEAN HUDSON., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The objective of this investigati.on was to contribute to the determination of a suitable metallic coating for steel reinforcement in concrete exposed to a marine environment and possibly to stray current. Concrete specimens embedded with steel, aluminum, cadmium, copper, molybdenum, nickel, and galvanized steel were exposed to sea water. Direct current was impressed on these to accelerate corrosion of the reinforcement so that cracking of the concrete could be observed within the time limit...
Show moreThe objective of this investigati.on was to contribute to the determination of a suitable metallic coating for steel reinforcement in concrete exposed to a marine environment and possibly to stray current. Concrete specimens embedded with steel, aluminum, cadmium, copper, molybdenum, nickel, and galvanized steel were exposed to sea water. Direct current was impressed on these to accelerate corrosion of the reinforcement so that cracking of the concrete could be observed within the time limit of the investigation. Aluminum, cadmium, copper, and nickel were found to have no beneficial effect on concrete cracking as compared to steel. In addition, no correlation between oxide-metal volume ratio and concrete time-to-cracking could be observed. It was found that corrosion of molybdenum has little or no tendency to crack concrete and its corrosion potential and active behavior approximates that of steel, indicating it may be an excellent coating.
Show less - Date Issued
- 1976
- PURL
- http://purl.flvc.org/fcla/dt/13820
- Subject Headings
- Reinforced concrete--Cracking, Underwater concrete construction, Reinforced concrete--Corrosion
- Format
- Document (PDF)
- Title
- A critical evaluation of current demand determination methods for cathodic protection retrofits of offshore structures.
- Creator
- Lemieux, Edward John., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Development of a baseline design protocol for cathodic protection retrofits of offshore structures is becoming an increasingly important topic in light of the large number of structures operating beyond their original cp system design life. One of the critical steps in this development is determination of the total anode mass which is required to continue sufficient cathodic protection for which structure current demand must be established. Three current demand determination methods were...
Show moreDevelopment of a baseline design protocol for cathodic protection retrofits of offshore structures is becoming an increasingly important topic in light of the large number of structures operating beyond their original cp system design life. One of the critical steps in this development is determination of the total anode mass which is required to continue sufficient cathodic protection for which structure current demand must be established. Three current demand determination methods were investigated including the Gaussian ammeter, the Potential method, which utilizes the driving potential and anode resistance in its current calculation, and the IR Drop method. To this end, three anodes were deployed at the Naval Research Laboratory, Key West, Fl., and current output determinations were made upon these. Each of the three current measurement methods was evaluated on the basis of accuracy, reliability and feasibility in field use.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/15503
- Subject Headings
- Cathodic protection, Offshore structures, Ocean currents
- Format
- Document (PDF)
- Title
- Design approaches for asymmetrical marine pipeline cathodic protection systems.
- Creator
- Qian, Haijun., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Marine pipeline cathodic protection systems for asymmetrical situation were systematically investigated by means of a newly proposed approach and Boundary Element Method (BEM). Potential attenuation profiles from BEM modeling indicate that far-field cathode potentials of different pipe sections approach identical values under different coating resistance and different electrolyte resistivity conditions provided anodes are separated by at least 10m and metallic resistance is negligible. A...
Show moreMarine pipeline cathodic protection systems for asymmetrical situation were systematically investigated by means of a newly proposed approach and Boundary Element Method (BEM). Potential attenuation profiles from BEM modeling indicate that far-field cathode potentials of different pipe sections approach identical values under different coating resistance and different electrolyte resistivity conditions provided anodes are separated by at least 10m and metallic resistance is negligible. A series of equations based on the Slope Parameter Method (SPM) has been modified for more extensive applicability. Several design examples have been analyzed and the results verified by BEM. Cathode potential and current demands projected by the new method are consistent with those of BEM. The inclusive equation for even anode spacing CP has been modified to include the cable parameters by combining cable resistance and the anode resistance. Current demand for existing pipelines can be determined by either of two methods. The first utilizes the inclusive equation and involves solving this for current demand based upon a known potential profile. The other is based on SPM.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fcla/dt/13098
- Subject Headings
- Underwater pipelines, Pipelines--Cathodic protection, Boundary element methods
- Format
- Document (PDF)