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Electrical Potentials. Electrical Potential Mapping. High corrosion risk at piles where splashing severe. High corrosion risk at construction joint due to easy access. High potential gradient between leeward and windward side of beams. Potential Wheel. CONTOUR PLOT:- SCANS:001-017
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Electrical Potential Mapping High corrosion riskat piles wheresplashingsevere High corrosion risk at construction joint due to easy access High potential gradient between leeward and windward side of beams
Potential Wheel CONTOUR PLOT:- SCANS:001-017 CONTOUR BOUNDARIES(MV) 0500 0400 0350 0300 0250 000 ROW RES:012MM COLUMN RES:015MM SCAN 001 V/G=100MV H/G=0200MM
Half-cell Potential Map of Roof Area Aonly 2 of 363 potentials: < -350 mV; 41 potentials : -200 to –350 mV (CSE)
Potential Curvature Map of the Roof Area A(Hot spots are highlighted along cracks/joints)
Potential Contour Map Potential Curvature Map
Electrical Potentials • British BS 1881, Testing Concrete Pt 201 • USA ASTM C876-91 • German DGZP B3 • Swiss SIA 2006 (most comprehensive)
Equipment Display unit Electrode
Corrosion Values Guideline Values (ACI 222) to determine possibility of corrosion for a Copper-Copper Sulfate Reference Electrode mV vs. CSE 0 to -200 -200 to -350 Less than -350 Probability of Corrosion <10% Uncertain >90%
Parking place inmulti-story car park Cumulative frequency Relative frequency
Potential Measurement • Requires skilled operative • For measurement • Ensure stable measurement • Determine if results will be meaningful • For interpretation • assess other factors affecting the result • Use to: • identify if corrosion initiated • locate areas for laboratory samples • determine extent of corrosion activity • Affects method of repair • For assessment of quantities