galva pulse
TRANSCRIPT
GalvaPulsefor
ELECTRICAL RESIST ANCE, HALF-CELL POTENTIALS ,
&
CORROSION RATE
Features
• Estimation of the reinforcement corrosion rate in less than 10 seconds.
• Reliable evaluation of reinforcement corrosion in anaerobic concrete
environment.• Half-cell potential along wi th the electrical resistance of the cover lay er.
• Lightweight electrode, handheld computer and easy-to-operate software.
• Durable guard ring system for focusing the current field to the reinforcement.
• Measurement on uneven and rough surfaces.
• Easy data export to Windows PCs for plotting of data.
Tel.: (21)3154-3250 / 3154-3251 Fax.: (21) 3154-3259
Rogertec
Rua Correia de Araújo, 131Barra da Tijuca - Rio de JaneiroCep 22611-060 - RJ - Brasil
ROGERTEC®
RO
GER
TEC
GalvaPulse '
System Overview
Germann Instruments’ GalvaPulse utilizes the
galvanostatic pulse method, which is the latest
technique for assessing the risk of corrosion to
the reinforcement in concrete structures.Trad itional corrosion mapping can lead to
misinterpretation of potential readings when
encountering an extremely wet, dense or
polymer-modified concrete that has limited
access to oxygen.The galvanostatic pulse method induces a short
duration anodic current pulse into the reinforcement galvaostatically via a measuring
cell that consists of three elements: a counter electrode, a reference electrode and a
guard ring (See next page).
The applied current is usually in the range of 5 to 400µA. The typical duration of thecurrent pulse is up to 10 seconds. The reference electrode records the resulting
change in electro-chemical potential of the reinforcement as a function of polarization
time.
As with other corrosion mapping systems, the concrete cover must be exposed to
determine that each length of reinf o rcement be intact electricall y. For estimating thecorrosion rate, the rebar size needs to be known.
Estimating Corrosion Rate
By utilizing the ohmic resistance (electricalresistance), the DC polarization resistance
over time, and the applied current, the
corrosion current can be estimated with
the Stern Geary equation.
When the diameter of the corrodingreinforcement and its exposed length are
known, the confined reinforcement area
can be calculated.
Faraday’s law of electrical equivalence
states that 1mA/cm2 corresponds to a cross section loss of approximately 10mm/year . The corrosion rate can be estimated b y the fo llowing equation.
Corrosion Rate ~ 10.Icorr
/A
The corrosion rate is in µm/year .I
corris the corrosion current in µA.
“A” is the confined area of the reinfo rcement in cm 2.
Tel.: (21)3154-3250 / 3154-3251 Fax.: (21)3154-3259
Rogertec
Rua Correia de Araújo,131Barra da Tijuca - Rio de JaneiroCep 22611-060 - RJ - Brasil
ROGERTEC®
RO
GER
TEC
GalvaPulse '
Three-element measuring cell
The design of the three-element
measuring cell is due to the nature of real
world RC structures. The GalvaPulse’ scounter electrode is much smaller than
that of the reinforcement, resulting in the
electrical signal tending to vanish with
increasing cover to the reinforcement.
As a result, the measured effectivepolarization resistance cannot be connot
be converted to a corrosion rate unless a
second concentric counter electrode is used. This guard ring confines the applied
current to an area equivalent to the first counter electrode.
PSION Workabout datalogger
A PSION Workabout handheld computer recor ds the data, which
can be downloaded to a Windows-based software for print out on
an IBM-compatible PC. The readings can be exported to MicrosoftExcel. The suplied “GalvaPulse Data Veiwing and Reporting
Program” can graphically display the potentials, electrical resistance
and corrosion rate in 2D or 3D charts.
A pulse generator to supply the applied current is mounted on the
back of the PSION.To check the perf ormance of the GalvaPulse, a
concrete sample cast with a corroding rebar and
a stainless steel bar is supplied with the kit.
Data Viewing
Graphics
Corrosion activity
represent in coloras
2D o r 3D
Tel.: (21)3154-3250 / 3154-3251 Fax.: (21)3154-3259
Rogertec
Rua Correia de Araújo,131Barra da Tijuca - Rio de JaneiroCep 22611-060 - RJ - Brasil
ROGERTEC®
RO
GER
TEC
GalvaPulse '
GP-5000 GalvaPulse Kit contains:
• PSION Workabout computer/dataloggerwith installed GalvaPulse software and
at tached pulse gener ator .
• Measuring cell with 6 meter cable.
• Sponge for measuring cell.
• Reinfo rcement locator .• Reinfo rcement conductivity meter .
• Cable for data transfer to PC.
• Measuring cable, banana plugs.
• Two adjustable clamping pliers.
• Four spare batteries for PSION.• Bottle of tap water .
• 12mm and 18mm drill bits.
• Emery cloth.
• Two reinf o rcement adaptors.
• 10mm Al len key.• Hammer .
• Measuring tape.
• Chalk.
• CD-ROM with GalvaPulse Data Viewing
and Reporting Program for Windows PCManuals.
• Foam-lined carrying case.
Supplied sperately with kit:
• Cable drum with 15 meters of cable.• Concrete sample with a corroding
rebar and a stainless steel rebar .
Dimensions of sample may vary
with kit.
Tel.: (21)3154-3250 / 3154-3251 Fax.: (21)3154-3259
Rogertec
Rua Correia de Araújo,131Barra da Tijuca - Rio de JaneiroCep 22611-060 - RJ - Brasil
ROGERTEC®
RO
GER
TEC