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Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
1. International
OPEN
Journal
ACCESS
Of Modern Engineering Research (IJMER)
Health Monitoring of Reinforcement In Concrete Piers In A
Barrage Project
S. N. Sharma1, Pankaj Sharma2, R. P. Pathak3, Sameer Vyas4, N. V. Mahure5,
S. L. Gupta6
(Central Soil and Materials Research Station, New Delhi, India)
ABSTRACT: Useful life of any barrage project depends on functional stability of the concrete piers.
The piers are constructed using concrete of different grades. Its durability is dependent on various factors
viz. speed of running water, its aggressively, temperatures fluctuations etc. The endurance capacity of
these piers against these adverse conditions is goes on reducing with passage of time. Gradually
permeability of concrete increases which causes corrosion of reinforcement thus weakening of concrete.
Once such a phenomenon is observed in any such structures a vigilant periodic monitoring approach
becomes mandatory. The suitable remedial measure to be adopted will depend on the observed degree of
deterioration. In this paper effort has been made to diagnose degree of corrosion of reinforcement in the
piers of a barrage project using Half Cell Potentiometer.
Keywords: Corrosion, Half cell potentiometer, Piers, Rebar, Reinforcement.
I. INTRODUCTION
Corrosion problems are very common in almost all aspects of technology resulting in cropping of
variety of problems. Corrosion damage in the reinforcement is an enormous economic liability. In a barrage
project piers are constructed using concrete of different grades. The permeated water causes corrosion of
reinforcement leading to weakening of structure [1] and spalling of cover (Fig. 1.1).
Fig. 1.1 Exposed reinforcement in piers due to spalling of cover
Diagnosis of the intensity of corrosion and its constant monitoring will provide useful information for
adopting suitable preventive measures [2]. In this paper effort has been made to diagnose degree of corrosion of
reinforcement in the piers of a barrage project using Half Cell Potentiometer.
II. METHOD ADOPTED
2.1. Half – Cell Electrical Potential Method to Measure Corrosion of Reinforcement in Concrete (ASTM
C 876-91)
The Half Cell Potential Testing method is a technique, used for assessment of the durability of
reinforced concrete and helps in diagnosing reinforcement corrosion [2, 3]. The method of half cell potential
measurements normally involves measuring the potential of an embedded reinforcing bar relative to a reference
half cell placed on the concrete surface. The half cell is usually Copper/ Copper Sulphate or Silver/ Silver
Chloride cell but other combinations are used. The concrete functions as an electrolyte and the risk of corrosion
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2. Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
of reinforcement in immediate region of the test location may be related empirically to the measured potential
difference. The typical layout of the equipment is shown Fig. 2.1.
The half cell consist a rigid tube composed of dielectric material that is non-reactive with copper or
copper sulphate, a porous wooden or plastic plug that remains wet by capillary action, and a copper rod that is
immersed within the tube in a saturated solution of copper sulphate. The solution is prepared using reagent
grade copper sulphate dissolved to saturation in distilled or deionized water. An electrical junction device is
used to provide a low electrical resistance liquid bridge between the surface and the half cell is normally a
sponge. Electrical contact solution is made from normal house hold detergent.
Fig 2.1 Copper- Copper Sulphate Half- Cell
Measurements are made in either a grid or random pattern. The potential risks of corrosion based on potential
difference readings [3] are presented in Table I.
Table I: The potential risks of corrosion based on potential difference readings
Potential difference levels (mv)
Chance of re-bar being corroded
less than -500mv
Visible evidence of Corrosion
-350 to -500 mv
95%
-200 to -350 mv
50%
More than -200 mv
5%
III. EQUIPMENT USED
Following equipments were deployed for the corrosion monitoring of reinforcement in concrete (Fig. 3.1)
- Micro cover meter- R Meter MKIII
- Half Cell Surveyor- CORMAP II
Micro Cover Meter
Half Cell Surveyor
Fig 3.1. Equipments Deployed for Investigation
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3. Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
The micro cover meter has been used to locate the rebar [4]. The concrete surface was examined for the exposed
rebars/or got exposed to get a reference point. Surface was made wet and observation locations were marked on
the surface [5]. The pre -activated Cu-CuSO4 Half Cell was used to take observation.
The test results are categorized in 7 categories from A to G category in the typical map recorded on
CORMAP II, their interpretation is given in Table II.
Table II: Categories of Corrosion Activity
A = - 0.420, B = - 0.350
A & B – 90% chance corrosion is occurring in this area
C = - 0.280 D = - 0.210
C & D – Corrosion activity over this area is uncertain
E = - 0.140 F = - 0.070 E –G – 90% chance that no corrosion activity is present
G= - 0.00
over this area
IV. TEST LOCATIONS
Detailed location of different piers and grid patterns are given in Table III.
Pier
1
2
3
4
5
6
7
8A
8B
9
10
Table III: Details of locations for corrosion monitoring
Location
D/S RHS FACE, 3.2m from gate.
D/S RHS FACE, 2.5m inside from nose of the pier
D/S RHS FACE
D/S LHS FACE
D/S RHS FACE
D/S RHS FACE, mid of the face, 20.5m apart from gate, lower end of the
grid ended at 10.3m from top.
D/S RHS FACE, mid of the face, 19.5m apart from gate, 4.7m from top.
D/S RHS, 10.7m from top, 1.0 m above water level, 29.0 m apart from gate
D/S RHS, 10.9 m from top & 27.0 m apart from gate. 0 m above water level
RHS, 11.55m from top and 1.0 m above water level, 23.4 m apart from gate
LHS, 11.5m from top and 1.0 m above water level, 13.7 m apart from gate
Grid pattern
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (column x row)
10’x5’ (row x column)
20’ x 10’ (10 x 10)
V. OBSERVATIONS
The investigation work of corrosion monitoring of the identified concrete piers was restricted to the
area which could be accessed using a boat (Table 3). The observed values for the tests done on different piers
are presented in Fig. 6.1 to Fig. 6.22 in the form of contour map and pie chart [6, 7, 8].
VI. RESULTS AND DISCUSSION
Map-3
6.1. Pier 1
Only 2% region falls in „D‟ category depicting uncertain corrosion activity while remaining 98% (6%
in „E‟, 70% in „F‟ and 22% in „G‟) area falls in categories which are indicative of no noticeable corrosion
0%
activity in the scanned area of the pier.
0%
0%
-0.3--0.2
-0.2--0.1
0-0.1
Potential
in mV
A > -0.42
-0.1-0
0.1-0.2
6%
9
D
22%
C > -0.28
7
E > -0.14
F
3
G > 0.00
3
5
7
9
11
13
15
17
1
19
70%
G
C olumns
Fig. 6.1 Contour Map Showing Corrosion Status
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D > -0.21
E
R ows
5
1
B > -0.35
2%
Fig. 6.2 Pie Chart of Scanned Area
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F > -0.07
4. Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
Map-3
6.2. Pier 2
Only 33% region falls in „D‟ category depicting uncertain corrosion activity while remaining 67%
(20% in „E‟, 16% in „F‟ and 31% in „G‟) area falls in categories which are indicative of no noticeable corrosion
0%
activity in the scanned area of the pier.
0%
0%
-0.3--0.2
0-0.1
Potential
in mV
-0.2--0.1
A > -0.42
-0.1-0
0.1-0.2
B > -0.35
D
9
C > -0.28
33%
31%
E
7
E > -0.14
R ows
5
3
7
9
11
13
15
FG >
16%
F > -0.07
0.00
20%
1
19
17
D > -0.21
G
C o lu mn s
Fig. 6.3 Contour Map Showing Corrosion Status
Fig. 6.4 Pie Chart of Scanned Area
Map-3
6.3. Pier 3
Only 2% region falls in D category depicting uncertain corrosion activity while remaining 98% (6% in
„E‟ , 42% in „F‟ and 50% in „G‟) area falls in categories which are indicative of no noticeable corrosion activity
0%
in the scanned area of the pier.
0%
0%
A > -0.42
Potential
in mV
-0.3--0.2
-0.2--0.1
-0.1-0
6%
D
9
C > -0.28
7
3
3
5
7
9
11
13
15
17
E > -0.14
50%
42%
F
G > 0.00
G
1
19
C olumns
Fig. 6.5 Contour Map Showing Corrosion Status
Fig. 6.6 Pie Chart of Scanned Area
6.4. Pier 4
100% area (43% in „F‟ and 57% in „G‟) falls in categories which are indicative of no noticeable
corrosion activity in the scanned area of the pier.
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D > -0.21
E
R ows
5
1
B > -0.35
2%
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F > -0.07
5. Map-3
0%
Health Monitoring of Reinforcement In Concrete Piers 0% A Barrage Project
In
0%
A > -0.42
Potential
in mV
-0.15--0.1
-0.1--0.05
B > -0.35
C > -0.28
F
D > -0.21
E > -0.14
F > -0.07
-0.05-0
9
5
R ows
7
43%
57%
3
G > 0.00
1
3
5
7
9
11
13
15
17
G
1
19
C olumns
Fig. 6.7 Contour Map Showing Corrosion Status
Fig. 6.8 Pie Chart of Scanned Area
Map-3
6.5. Pier 5
100% area (18% in „F‟ and 82% in „G‟) falls in categories which are indicative of no noticeable
0%
corrosion activity in the scanned area of the pier.
0%
0%
A > -0.42
Potential
in mV
-0.15--0.1
-0.1--0.05
B > -0.35
-0.05-0
F
9
18%
C > -0.28
D > -0.21
E > -0.14
F > -0.07
5
R ows
7
3
1
3
5
7
9
11
13
15
17
G>
G
1
19
0.00
82%
C olumns
Fig. 6.9 Contour Map Showing Corrosion Status
Fig. 6.10 Pie Chart of Scanned Area
Map-3
6.6. Pier 6
Only 14% region (2% in „C‟ and 12% in ‟D‟ category) depicts uncertain corrosion activity while
remaining 86% (46% in „E‟ and 40% in „F‟) area falls in categories which are indicatives of no noticeable
0, 0%
corrosion activity in the scanned area of the pier.
0, 0%
A > -0.42
Potential
in mV
-0.3--0.2
-0.2--0.1
12%
9
C
C > -0.28
R ows
5
E > -0.14
E
3
G > 0.00
3
5
7
9
11
13
15
17
1
19
46%
C olumns
Fig. 6.11 Contour Map Showing Corrosion Status
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D > -0.21
D
40%
7
1
B > -0.35
2%
-0.1-0
Fig. 6.12 Pie Chart of Scanned Area
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F
F > -0.07
6. Map-3
Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
0%
0%
6.7 Pier 7
A > -0.42
Potential
in mV
-0.3--0.2
-0.2--0.1
4%
-0.1-0
D
4%
9
C > -0.28
23%
R ows
7
5
B > -0.35
D > -0.21
E
E > -0.14
F > -0.07
F
69%
3
G > 0.00
1
3
5
7
9
11
13
15
17
1
19
G
C olumns
Fig. 6.13 Contour Map Showing Corrosion Status
Fig. 6.14 Pie Chart of Scanned Area
Only 4% region falls in „D‟ category depicting uncertain corrosion activity while remaining 96% (4% in „E‟ ,
23% in „F‟ and 69% in „G‟) area falls in categories which are indicatives of no noticeable corrosion activity in
the scanned area of the pier.
Map-3
6.8. Pier 8 A
100% area (28% in „E‟, 56% in „F‟ and 16% in „G‟) falls in categories which 0% indicatives of no
are
noticeable corrosion activity in the scanned area of the pier.
0%
0%
0%
A > -0.42
Potential
in mV
-2--1.5
-1.5--1
-1--0.5
B > -0.35
C > -0.28
D > -0.21
E > -0.14
F > -0.07
E
-0.5-0
9
16%
28%
F
5
R ows
7
3
G > 0.00
1
3
5
7
9
11
13
15
17
56%
1
19
C olumns
Fig. 6.15 Contour Map Showing Corrosion Status
G
Fig. 6.16 Pie Chart of Scanned Area
Map-3
6.9. Pier 8 B
100% area falls in „G‟ category which indicates no noticeable corrosion activity in the scanned area of
the pier.
0%
A > -0.42
-0.06--0.04
-0.04--0.02
B > -0.35
C > -0.28
Potential
in mV
D > -0.21
-0.02-0
9
7
G
E > -0.14
R ows
5
3
100%
1
3
5
7
9
11
G > 0.00
1
13
C o lu mn s
Fig. 6.17 Contour Map Showing Corrosion Status
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Fig. 6.18 Pie Chart of Scanned Area
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F > -0.07
7. Map-3
Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
0%
6.10. Pier 9
0%
A > -0.42
-0 .4 --0 .3
Potential
in mV
-0 .3 --0 .2
-0 .2 --0 .1
8%
-0 .1 -0
9
C > -0.28
C
21%
Rows
7
5
B > -0.35
B
8%
E
F>
-0.14
D > -0.21
F > -0.07
40%
3
G > 0.00
D
23%
1
1
3
5
7
9
E
C o lu m n s
Fig. 6.19 Contour Map Showing Corrosion Status
Fig. 6.20 Pie Chart of Scanned Area
6.11. Pier 10
5% scanned area fall under categories „A‟ & „B‟, depicting , 90% chance of corrosion is occurring in
Map-3
this area whereas 27% area fall under categories „C‟ & „D‟ showing uncertain corrosion activity. 68% area (49%
in „E‟, 16% in „F‟ and 3% in „G‟ categories) falls in area which are indicatives of no noticeable corrosion
activity in the scanned area of the pier. The general look of exposed rebar shown in figure 1 is also evident of
vigorous corrosion activities in the area.
Potential
in mV
-0.5--0.4
-0.4--0.3
-0.2--0.1
-0.1-0
2%
A
A>
3%
-0.42
B > -0.3
C > -0.28
3%
-0.3--0.2
D > -0.2
6%
10
B
16%
9
8
21%
C
7
5
E
D>
R ows
6
4
G
3
2
G > 0.00
49%
1
10 12 13 14 15 16 17 18 19 19
C o lu m n s
Fig. 6.21 Contour Map Showing Corrosion Status
Fig. 22 Pie Chart of Scanned Area
VII. CONCLUSION
The Half Cell Potential Testing method is a technique, used for assessment of the durability of reinforced
concrete and helps in diagnosing reinforcement corrosion. As per standard practices stated above, the test results
shows that
No corrosion activity is detected on pier no 4, 5, 8A and 8B.
Corrosion activity has already initiated on the piers 1, 2, 3, 6, 7.
Scanning result on pier no. 9 and 10 shows high degree of corrosion.
Since indications of deterioration of concrete and reinforcement have been observed a strict vigil through
periodic monitoring of these piers should be kept using Non Destructive Tests.
Acknowledgements
The authors extend their sincere thanks to Director CSMRS for his constant inspiration. We also extend our
sincere gratitude to Sh. Sohan Singh of CSMRS for his valuable efforts. We also extend our sincere gratitude to
all the authors whose publications provided us directional information from time to time.
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-0.14
| Vol. 4 | Iss. 1 | Jan-Feb. 2014 |7|
E
F
F > -0.0
8. Health Monitoring of Reinforcement In Concrete Piers In A Barrage Project
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