- Rebar Linear Polarisation Resistance
- Rebar Electrical Potential
- Concrete Resistance
Linear polarisation resistance is measured by passing a small current from the auxiliary electrode to shift the potential of the reinforcing steel by a fixed amount.
The polarisation resistance is the potential shift divided by the current applied; it is inversely proportional to the corrosion rate. Faraday's Law can be used to convert the corrosion rate current in μAcm-2 to steel section loss in microns per year. Approximately 100microns section loss rate will cause cracking and spalling of concrete.
For more details on electrical potentials and resistivity techniques refer to PCTE brochure for the CANIN+ from Proceq.
A range of corrosion monitoring probes for new structure includes:
- Embedded LPR probes located during the pour of any new structure for a single LPR measurement
- Ladder (CL) Probes for determining the rate of ingress of corrosive reagents.
All embedded LPR probes are identified uniquely using an identification chip.
Type of Probes
Embeddable LPR Probe/Products/Corrosion/Monitor-New-Structure/monnew1.aspx)
The Embeddable LPR Probe measures the corrosion rate, corrosion potential, for a single element and the rebar, as well as the concrete resistance and concrete temperature. Installation is carried out pre-pour by tying to the rebar. Connections to the rebar allow two corrosion rates to be collected (from the carbon steel electrode and the rebar).
Ladder (CL) Probe
The Ladder (CL) Probe has been designed to provide information over a varying depth profile. Four independent LPR electrodes at varying levels of concrete cover – allow the determination of Corrosion Rate and Half Potential for the elements and the rebar. Additionally the concrete resistances at 3 points, temperature are measured. The ingress of corrosive activators as well as the o/Products/Corrosion/Monitor-New-Structure/monnew2.aspx)
verall performance of the concrete can thus be monitored as initiation and rate of corrosion at the elements and the rebar is measured over the structures life.
Control Systems
Portable Data Collection System (PDCS)
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The PDSC meter is a self-contained battery powered instrument which provides compatibility with the PCTE’s range of embeddable probes. The system is controlled by an integrated laptop with Windows 7 operating system. The PDCS firmware controls the measurement process, where the corrosion potential (Ecorr) and corrosion rate automatically measured by selecting the appropriate menu.
Network Controller
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This automated control and logging system is large enough to cater for Corrosion Monitoring system whether it includes retrofit probe or imbedded rack probes. Readily connected to networks this system can be programmed to log LPR measurements at predetermined intervals. It can be stored locally for downloading to a laptop at regular maintenance interval or sent through a network via Modbus protocol, emailed to remote locations as an ASCII file readily usable in most spreadsheet formats or any other convenient method.
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