Building & Construction Research and ConsultancyBCRC

Electrical Potentials

Building & Construction Research and ConsultancyBCRC

Electrical Potential Mapping

High corrosion risk at construction joint due

to easy accessHigh potential gradient between leeward and

windward side of beams

High corrosion riskat piles wheresplashingsevere

Building & Construction Research and ConsultancyBCRC

Potential WheelCONTOUR 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

Building & Construction Research and ConsultancyBCRC

Half-cell Potential Map of Roof Area A only 2 of 363 potentials: < -350 mV; 41 potentials : -200 to –350 mV (CSE)

0.0 0.5 1.0 1.5 2 .0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6 .0 6.5 7.0 7.5 8.0

Length South tow ards N orth (m )

0.0

0.5

1.0

1.5

2.0

2.5

Wid

th E

ast t

owar

ds W

est (

m)

Building & Construction Research and ConsultancyBCRC

Potential Curvature Map of the Roof Area A

(Hot spots are highlighted along cracks/joints)

0.0 0.5 1.0 1.5 2 .0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6 .0 6.5 7.0 7.5 8.0

Length S outh tow ards N orth (m )

0.0

0.5

1.0

1.5

2.0

2.5

Wid

th E

ast t

owar

ds W

est (

m)

Building & Construction Research and ConsultancyBCRC

0.0 0.5 1.0 1.5 2 .0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6 .0 6.5 7.0 7.5 8.0

Length South tow ards N orth (m )

0.0

0.5

1.0

1.5

2.0

2.5

Wid

th E

ast t

owar

ds W

est (

m)

0.0 0.5 1.0 1.5 2 .0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6 .0 6.5 7.0 7.5 8.0

Length South tow ards N orth (m )

0.0

0.5

1.0

1.5

2.0

2.5

Wid

th E

ast t

owar

ds W

est (

m)

Potential Curvature Map

Potential Contour Map

Building & Construction Research and ConsultancyBCRC

Electrical Potentials British BS 1881, Testing Concrete Pt 201 USA ASTM C876-91 German DGZP B3 Swiss SIA 2006 (most comprehensive)

Building & Construction Research and ConsultancyBCRC

Equipment

ElectrodeDisplay unit

Building & Construction Research and ConsultancyBCRC

Canin with 4 wheel probe array

Building & Construction Research and ConsultancyBCRC

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%

Building & Construction Research and ConsultancyBCRC

m

0.00

0.15

0.30

0.45

0.60

0.75

0.90

1.05

1.20

1.35

1.50

1.65

1.80

1.95

2.10

2.25

0.000.150.300.450.600.750.901.051.201.351.501.651.801.952.102.252.402.552.702.853.003.153.303.453.603.753.904.054.204.354.504.654.804.95

Cumulative frequencyRelative frequency

Parking place inmulti-story car park

Building & Construction Research and ConsultancyBCRC

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