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Hydrogen embrittlement of cathodically protected prestressing steel
Title
Hydrogen embrittlement of cathodically protected prestressing steel.
Creator
Kliszowski, Stanislas Henri., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Cathodic protection is currently recognized as the most practical mean for arresting corrosion of reinforcing steel tendons in existing concrete structures, however, its appropriateness in the case of prestressed concrete is questioned because prestressing steels are relatively susceptible to environmental cracking (hydrogen embrittlement). For the purpose of studying embrittlement tendencies a series of experiments using the slow strain rate technique were performed. The susceptibility to...
Show moreCathodic protection is currently recognized as the most practical mean for arresting corrosion of reinforcing steel tendons in existing concrete structures, however, its appropriateness in the case of prestressed concrete is questioned because prestressing steels are relatively susceptible to environmental cracking (hydrogen embrittlement). For the purpose of studying embrittlement tendencies a series of experiments using the slow strain rate technique were performed. The susceptibility to environmental cracking was compared for different steels corresponding to ASTM grades 270 and 250 polarized at $-$900 and $-1300$ mV (SCE) in deaerated saturated Ca(OH)$\sb2$ solutions. The influence of different notch and pit geometries was studied to simulate the behavior of corroded tendons and investigate the transition between smooth and severely notched specimen behavior. Also evaluated was the evolution of the mechanical properties of tendons after excessive polarization. The different cracking processes are discussed based on test data, fractography and exposures conditions associated with concrete structures.
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Date Issued
1994
PURL
http://purl.flvc.org/fcla/dt/14999
Subject Headings
Cathodic protection, Metals--Hydrogen embrittlement, Tendons (Prestressed concrete), Prestressed concrete--Deterioration, Prestressed steel construction
Format
Document (PDF)
Embrittlement susceptibility of corroded pre-stressing steel in concrete during cathodic polarization
Title
Embrittlement susceptibility of corroded pre-stressing steel in concrete during cathodic polarization.
Creator
Poeydomenge, Arnaud., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Experiments and analyses were performed to better define the limits of concern regarding hydrogen embrittlement in association with application of cathodic protection to prestressed concrete. To accomplish this, prestressed concrete specimens were locally corroded to different levels by anodic polarization and then polarized to -1.30 V SCE. A procedure of examination was developed using strain gauges to determine the level of prestrain. Relatively few brittle failures of wires resulted due,...
Show moreExperiments and analyses were performed to better define the limits of concern regarding hydrogen embrittlement in association with application of cathodic protection to prestressed concrete. To accomplish this, prestressed concrete specimens were locally corroded to different levels by anodic polarization and then polarized to -1.30 V SCE. A procedure of examination was developed using strain gauges to determine the level of prestrain. Relatively few brittle failures of wires resulted due, at least in part, to a relatively low prestrain of the pretensioned tendons. A model was developed which, coupled with data from parallel research, permitted definition of the minimum cross section for brittle failure as a function of the magnitude of prestrain and corrosion morphology of the wire. These results were tabulated in a format that can be used during field inspection to identify structural elements for which fracture could occur upon application of cathodic protection.
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Date Issued
1997
PURL
http://purl.flvc.org/fcla/dt/15417
Subject Headings
Prestressed concrete--Corrosion, Cathodic protection, Prestressed concrete--Embrittlement, Prestressed steel construction
Format
Document (PDF)
Effect of cathodic protection on bond strength between prestressing steel and concrete
Title
Effect of cathodic protection on bond strength between prestressing steel and concrete.
Creator
Ducrocq, Luc., Florida Atlantic University, Hartt, William H.
Abstract/Description
A series of experiments was performed on prestressed concrete specimens for the purpose of studying the tendency of disbonding between the embedded steel and the concrete due to an impressed cathodic current. The procedure first involved impressing an anodic current until active potentials were recorded along the tendon length. Subsequently, cathodic polarization of the prestressed tendons was affected using a current density of 1 mA/cm^2. The strain variation of the concrete specimens was...
Show moreA series of experiments was performed on prestressed concrete specimens for the purpose of studying the tendency of disbonding between the embedded steel and the concrete due to an impressed cathodic current. The procedure first involved impressing an anodic current until active potentials were recorded along the tendon length. Subsequently, cathodic polarization of the prestressed tendons was affected using a current density of 1 mA/cm^2. The strain variation of the concrete specimens was monitored during these two procedures using gages placed on the top or bottom surface. It was found that for a current density of 1 mA/cm^2 during the 30 day monitoring period the concrete relaxed by an amount equivalent to an 80 percent loss of bond between the tendons and concrete. The implications of this with regard to cathodic protection of prestressed concrete structures and components in actual service are discussed.
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Date Issued
1990
PURL
http://purl.flvc.org/fcla/dt/14591
Subject Headings
Prestressed steel construction, Prestressed concrete construction, Cathodic protection
Format
Document (PDF)