PREDICTION OF CORROSION ACTIVITY LEVELS OF ......solutions. The corrosion levels in the specimens are assessed by measuring the potential difference between specific points of specimen

\http://www.iaeme.com/IJCIET/index.asp 32 [email protected]

International Journal of Civil Engineering and Technology (IJCIET)

Volume 10, Issue 12, December 2019, pp. 32-49, Article ID: IJCIET_10_12_004

Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=12

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication

PREDICTION OF CORROSION ACTIVITY

LEVELS OF HYSD BARS IN OPC SCC AND GPC

BY ELECTRICAL RESISTIVITY METHOD AND

HALF CELL POTENTIAL METHOD

K. Kiran Siddhartha

P.G Student, G. Pulla Reddy Engineering College (Autonomous), Kurnool 518007, Andhra

Pradesh, India

G. Nagesh Kumar

Sr. Assistant professor

Civil Engineering Department, G. Pulla Reddy Engineering College (Autonomous), Kurnool

518007, Andhra Pradesh, India

E. Sanjeeva Rayudu

Associate professor

Civil Engineering Department, G. Pulla Reddy Engineering College (Autonomous), Kurnool

518007, Andhra Pradesh, India

ABSTRACT

Reinforced concrete structures have good potential to be durable and capable of

withstanding adverse environmental conditions. Failures in RCC structures will still

occur as a result of premature reinforcement corrosion. Corrosion of steel has been

recognized as one of the major durability problems in R.C.C structures. The damage

caused by corrosion considerably reduces the strength, serviceability and life of

structures. Inspection and continuous monitoring techniques necessarily have to be

carried out, to assess the steel corrosion in R.C.C structural components in order to

ensure their safety, serviceability and durability for a long time. They should be

required for their easy maintenance and repairs also few investigations were carried

out to study the corrosion level and flexural behavior of beams with corroded RCC

beams. Very few investigations were carried out to study such corrosion characteristics

in reinforcement in ordinary Portland concrete (OPC) beams, self- compacting

concrete (S.C.C) beams and Geopolymer concrete (G.P.C) beams so far. Problems

associated with corrosion of steel and possibility of its occurrence in ordinary Portland

concrete, self -compacting concrete and geo polymer concrete were to be studied.

K. Kiran Siddhartha, G. Nagesh Kumar and E. Sanjeeva Rayudu

http://www.iaeme.com/IJCIET/index.asp 33 [email protected]

In the present project work carried out the experimental studies on the corrosion of

reinforced self- compacting concrete specimens and Geopolymer concrete of different

grades (For example, M 25 and M 30 grades of conventional concrete) are carried out.

In making self-compacting concrete and Geopolymer concrete, fly ash and GGBS are

used as pozzolanic materials to replace cement partially. Specimens of size100 mm x

100 mm x 250 mm with centrally placed mild steel and HYSD bars are casted and

immersed in acidic solutions HCl, H2O and MgSO4 solutions to promote corrosion. The

specimens are cured for a period of 28days 60days and 90days respectively in those

solutions. The corrosion levels in the specimens are assessed by measuring the potential

difference between specific points of specimen by electrical resistivity Method (E.R

Method) and half-cell potential method.

Key words: Corrosion, Concrete; R.C.C beams; Half-cell potential method; Electrical

resistivity method

Cite this Article: K. Kiran Siddhartha, G. Nagesh Kumar and E. Sanjeeva Rayudu,

Prediction of Corrosion Activity Levels of Hysd Bars in OPC SCC and GPC by

Electrical Resistivity Method and Half Cell Potential Method. International Journal of

Civil Engineering and Technology, 10(12), 2019, pp.32-49

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=12

1. INTRODUCTION

Cement can be defined as the bonding material having cohesive & adhesive properties which

makes it capable to unite the different construction materials and form the compacted assembly.

Ordinary/Normal Portland cement is one of the most widely used type of Portland cement. Self

-compacting concrete (SCC) was the one which flows under its own weight and which does

not required any external vibration for its compaction and placement in the members. It is

highly workable concrete that flows through restricted sections under its own weight without

segregation and bleeding. Such concrete should have relatively a very low yield value to ensure

its very high flowing ability and moderate viscosity to resist segregation and bleeding.

Alternatively, it should maintain its homogeneity during its transportation, placing into the

casting elements and also curing to ensure adequate structural performance and long-term

durability for the members. Japan has developed and used SCC by the early 1990’s,

recognizing the requirement of concrete that does not require vibration to achieve full

compaction. SCC has become popular in Japan, by the year 2000, for making prefabricated

products and ready mixed concrete [1].

Deionized water for pH value 4 ,hydro chloric acid (HCl) in acidic nature and magnesium

sulphate (MgSO4) as a salt content in the sea water level these chemicals are used for the curing

purpose in progress of [1] has conducted the Analysis of half-cell potential measurement for

corrosion of reinforced concrete (Non-destructive evaluation techniques by the half-cell

potential measurement are applied to estimate the corrosion of reinforcing steel-bars in

concrete slabs under cyclic wet and dry conditions. The three-dimensional boundary element

method (BEM) is applied to study the potential distributions and current flows of rebar. [2]

Then, the inverse boundary element method (IBEM) is applied to experimental results to

identify the corrosion states) has conducted an project Effects of alkali solutions on corrosion

durability of Geopolymer concrete (This paper presents chloride induced corrosion durability

of reinforcing steel in Geopolymer concretes The corrosion activity is monitored by measuring

the copper/copper sulphate (Cu/CuSO4) half-cell potential according to ASTM C-876. Similar

behavior is also observed in sorptivity and chloride penetration depth measurements.

Prediction of Corrosion Activity Levels of Hysd Bars in OPC SCC and GPC by Electrical

Resistivity Method and Half Cell Potential Method


Generally, the Geopolymer concretes exhibited lower sorptivity and chloride penetration depth

than that of OPC concrete. Correlation between the sorptivity and the chloride penetration of

Geopolymer concretes is established. Correlations are also established between 28 days

compressive strength and sorptivity and between 28 days compressive strength and chloride

penetration of Geopolymer concretes [3]

Conducted Evaluation of the influence of salt concentration on cement stabilized clay by

electrical resistivity measurement method (2 January 2014) the influence of salt concentration

on the cementation process of cement stabilized clay is studied using the electrical resistivity

measurement. The clay with various sodium chloride salt concentrations was prepared

artificially and stabilized by Ordinary Portland cement with different contents. This is used for

general construction purposes where special properties are not required. It is normally used in

the reinforced concrete buildings, bridges, pavements, and where soil conditions are normal. It

is also used for most of concrete masonry units and for all uses where the concrete is not subject

to special sulfate hazard or where the heat generated by the hydration of cement is not

objectionable. It has great resistance to cracking and shrinkage, but has less resistance to

chemical attacks [4]

The purpose of this research was to evaluate the influences of concrete cover, chloride

content, compressive strength and moisture content on the half-cell potential measurement in

reinforced concrete structure. The relationship between the level of corrosion and the half-cell

potential value was also evaluated. Twenty one concrete slabs with the dimensions of 300 x 300 x 100 mm3 and three concrete slabs with the dimensions of 300 x 300 x125 mm3 were

prepared for various experimental cases; that is, three levels of cover (25, 50 and 100 mm),

three levels of chloride content (0.6, 1.2 and 1.8% by weight of cement content) and two levels

of compressive strength (17.65 and 20.59 MPa). After curing in water for 28 days, the half-cell

potential was measured in accordance with the ASTM C879 every week to detect corrosion

under wet-dry accelerated until 140 days [5]

Reinforcement corrosion is a major problem in the long-term management of reinforced

concrete structures. With sustainability in perspective, knowledge of the corrosion rate (Vcor)

makes it possible to estimate the kinetics of the corrosion phenomenon and helps in refining

the maintenance strategy of such structures. Although in situ Vcor measurements are possible,

data acquisition is time-consuming because of the protocol intrinsic to its measurement

(reinforcement polarization made point by point). Therefore, in the context of site diagnostics,

these methods cannot reasonably be used systematically on site and must be combined with

high performance non-destructive testing I had used the mix designs of M25 and M30 in this

grade as the mix designs by trail mixes it is necessary to reduce the water/binder ratio as well

as to increase the binder content I had used the mix designs of M25 and M30 in this grade as

the mix designs by trail mixes After aluminium and steel, supply position of the cement

industry had improved from 2008-09 onwards.

The current work used mix designs of M25 and M30 in this grade as the mix designs by

trail mixes

The present study deals with the prediction of corrosion activity levels of HYSD bars in

OPC, SCC,GPC by electrical resistivity method and half-cell potential method by having the

different grades of concrete and different curing conditions of 28 days 60 days and 90 days

periods using HCl and MgSO4 resulting different grades of concrete by destructive and non-

destructive methods.



2. MATERIALS USED AND THEIR PROPERTIES

2.1. R.C.C Materials

The steel bars with 16 mm ø as nominal size were chosen for reinforcing the concrete beams,

each reinforcement bar prior their usage was weighed, and moreover the dimensional properties

of the steel bar were recorded. Steel bars were then concreted into beams with dimensions of

100 mm × 100 mm × 250 mm with a uniform covering of 22 mm.

Figure:-1 Reinforced concrete beam measurement

Zuari brand 53 grade ordinary Portland cement (OPC) has been used in the present

experimental work. The cement used was fresh and free from lumps. The various tests on

cement were carried out as per IS: 12269-1987 and are presented

Fly ash is used in the mix proportion in self compacting concrete and Geopolymer concrete

as shown in the fig 2

Figure:-2 Fly Ash Powder

GGBS is used for the mixing GPC and SCC mixing in the mix proportion as shown in fig

3

Figure: -3 GGBS Powder

The specimen moulds that are used for the preparation specimen at exact spacing and

placing of the bar as shown in fig 4 &5




Figure: -4 Specimens with Beam Mould Figure: -5 Specimen Prepared

2.2. Chemicals that are used for the curing purpose

These chemicals that are used for the curing purpose of the chemicals that are shown in the

following figures.

Figure: -6 MgSO4 Figure:-7 HCl

3. MIX PROPORTIONS

The mix proportions for M25 and M30 grade of concrete were obtained in accordance with the

IS10262:2009 guidelines.

Table: - 1 Mix Proportioning for Normal Vibrated Concrete.

Specimen Grade Cement

(kg/m3)

Coarse

aggregate

(kg/m3)

Fine

aggregate

(kg/m3)

Water

(kg/m3)

w/c

Ratio

Compressive

strength(N/mm2)

M1 M25 383.16 1174.76 686.12 191.58 0.45 31.30

M2 M30 400.16 1185.76 696.12 198.58 0.50 35.30

Table:-2 Mix Proportioning for Self Compacting Concrete for M25 &M30

Speci

men

Gra

de

SP

(kg/

m3)

GGB

S

(kg/

m3)

VM

A

(ml

)

Cem

ent

(kg/

m3)

Coarse

aggregate

(kg/m3)

Fine

aggreg

ate

(kg/m3

)

Water

(kg/m3)

Water/Bi

nding

(or)Powe

r Ratio

Compressive

Strength

N/mm2

10m

m

20m

m

M3 M2

5 6 88.38 3 225

294.

5

294.

5 997 203 O.43 37.3

M4 M3

0 8 99.38 4 235 300 300 987 230 0.45 38.4



Table: - 3 Mix Proportioning for Geopolymer Concrete for M25 and M30

Speci

men Grade

Fly

ash

(kg/m

3)

GGB

S

(kg/m

3)

NaOH

Soluti

on

(kg/m

3)

Na2Si

O3

Solutio

n

(kg/m3

)

Coarse

aggregate

(kg/m3)

Fine

aggreg

ate

(kg/m

3)

Ratio

Betwe

en

NaoH

to

Na2Si

o3

Compres

sive

Strength

N/mm2 10m

m

20m

m

M5 M25 289.6 124.1 53.2 133.01 882 378 540 0.45 34.6

M6 M30 338.

331

144.9

9 69.04 188.47 886 384 545 0.45 35.9

4. EXPERIMENTAL PROCEDURE

In total, 54 of testing reinforced concrete beams were prepared using components of 540 kg of

cement (CEM II/B – S 32,5); 1400 kg of aggregates (2–4 mm) and 225 L of water. To accelerate

the migration of aggressive media to the steel reinforcement, the fine fraction of aggregates 0-

2 mm was excluded. Another 14 reinforced concrete beams with reinforcement 10 216 were

made to verify the changes of the electrical conductivity of reinforcement by the different

moisture contents of the concrete. During the time of exposure to an aggressive environment,

the overhang ends of the reinforcement bars were protected by the plug-polyethylene roller

with Vaseline. The steel bars in the length of 10 mm in the concrete were coated with polyester

paint for the elimination of possible resistances losses in this transition region. The scheme of

the reinforced concrete beam

4.1. Half-Cell Electrical Potential Method

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 [7].

The half-cell is usually a silver nitrate cell but other combinations are used. The concrete

functions as an electrolyte and the risk of corrosion of the reinforcement in the immediate

region of the test location may be related empirically to the measured potential difference. In

some circumstances, useful measurements can be obtained between two half-cells on the

concrete surface. ASTM C876 - 91 gives a Standard Test Method for Half-Cell Potentials of

Uncoated Reinforcing Steel in Concrete [6].

Figure: -8 Half-cell potential methods

Half-cell: The cell consists of a rigid tube or container 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 a distilled or deionized water [10].




4.2. Equipment’s that are used in this Process

1. Electrical junction device

2. Electrical contact solution

3. Voltmeter

4. Electrical lead wires

4.2.1. Applications

This technique is most likely to be used for assessment of the durability of reinforced concrete

members where reinforcement corrosion is suspected. Reported uses include the location of

areas of high reinforcement corrosion risk in marine structures, bridge decks and abutments.

Used in conjunction with other tests, it has been found helpful when investigating concrete

contaminated by salts

Figure: -9 Half -cell Potential Method Setup

4.3 TEST PROCEDURE

Measurements are made in either a grid or random pattern. The spacing between measurements

is generally chosen such that adjacent readings are less than 150 mV with the minimum spacing

so that there is at least 100 mV between readings. An area with greater than150 MV indicates

an area of high corrosion activity. A direct electrical connection is made to the reinforcing steel

with a compression clamp or by brazing or welding a protruding rod. To get a low electrical

resistance connection, the rod should be scraped or brushed before connecting it to the

reinforcing bar. It may be necessary to drill into the concrete to expose a reinforcing bar. The

bar is connected to the positive terminal of the voltmeter. One end of the lead wire is connected

to the half-cell and the other end to the negative terminal of the voltmeter. Under some

circumstances the concrete surface has to be pre-wetted with a wetting agent. This is necessary

if the half-cell reading fluctuates with time when it is placed in contact with the concrete. If

fluctuation occurs either the whole concrete surface is made wet with the wetting agent or only

the spots where the half-cell is to be placed [11]. The electrical half-cell potentials are recorded

to the nearest 0.01 V correcting for temperature if the temperature is outside the range 22.2 ±

5.5oC. Measurements can be presented either with an equipotential contour map which

provides a graphical delineation of areas in the member where corrosion activity may be

occurring or with a cumulative frequency diagram which provides an indication of the

magnitude of the affected area of the concrete member [3].

Equipotential Contour Map: On a suitably scaled plan view of the member the locations of

the half-cell potential values are plotted and contours of equal potential drawn through the

points of equal or interpolated equal values. The maximum contour interval should be 0.10V

[3].



Cumulative frequency distribution: The distribution of the measured half-cell potentials

for the concrete member are plotted on normal probability paper by arranging and

consecutively numbering all the half-cell potentials in a ranking from least negative potential

to greatest negative potential.

4.4. ELECTRICAL RESISTIVITY METHOD

Specimen and their formulae’s

Figure: -10 Electrical Conduction Paths

Figure: -11 Resistivity in ohms representation

Figure:-12 Resistivity method setup

4.5 ELECTRICAL RESISTIVITY METHOD PROCEDURE

4.5.1. Two Electrode

Concrete electrical resistance can be measured by applying a current using two electrodes

attached to the ends of a uniform cross-section specimen. Electrical resistivity is obtained from

the equation, {\displaystyle \rho =R{\frac {A}{\ell }},\,\!}R is the electrical resistance of the

specimen, the ratio of voltage to current {\displaystyle \ell } is the length of the piece of material

A is the cross-sectional area of the specimen. This method suffers from the disadvantage that

contact resistance can significantly add to the measured resistance causing inaccuracy.

Conductive gels are used to improve the contact of the electrodes with the sample.

4.5.2. Four Electrodes

The problem of contact resistance can be overcome by using four electrodes. The two end

electrodes are used to inject current as before, but the voltage is measured between the two

inner electrodes. The effective length of the sample being measured is the distance between the

https://en.wikipedia.org/wiki/Electrical_resistance




two inner electrodes [10]. Modern voltage meters draw very little current so there is no

significant current through the voltage electrodes and hence no voltage drops across the contact

resistances.

4.5.3. Transformer Method

In this method a transformer is used to measure resistivity without any direct contact with the

specimen. The transformer consists of a primary coil which energy is as the circuit with an AC

voltage and a secondary which is formed by a toroid of the concrete sample [11]. The current

in the sample is detected by a current coil wound around a section of the toroid (a current

transformer). This method is good for measuring the setting properties of concrete, its hydration

and strength. Wet concrete has a resistivity of around 1 Ω-m which progressively increases as

the cement sets.

4.5.4. On-Site Methods

4.5.4.1. Four probes

On-site electrical resistivity of concrete is commonly measured using four probes in a Wenner

array. The reason for using four probes is the same as in the laboratory method - to overcome

contact errors. In this method four equally spaced probes are applied to the specimen in a line.

[8]The two outer probes induce the current to the specimen and the two inner electrodes

measure the resulting potential drop. The probes are all applied to the same surface of the

specimen and the method is consequently suitable for measuring the resistivity of bulk concrete

in situ.

The resistivity is given by:

\displaystyle \rho =2\pi a{\frac {V}{I}}}V is the voltage measured between the inner two

probes

I is the current injected in the two outer probes

A is the equal distance of the probes.

4.5.5 Rebar

The presence of rebars disturbs electrical resistivity measurement as they conduct current much

better than the surrounding concrete. This is particularly the case when the concrete cover depth

is less than 16 mm. In order to minimize the effect, placing the electrodes above a rebar is

usually avoided, or if unavoidable, then they are placed perpendicular to the rebar. However,

measurement of the resistance between a rebar and a single probe at the concrete surface is

sometimes done in conjunction with electrochemical measurements.[6] Resistivity strongly

affects corrosion rates and electrochemical measurements require an electrical connection to

the rebar. It is convenient to make a resistance measurement with the same connection.

The resistivity is given by:

ρ = 2RD{\displaystyle \rho =2RD}

R is the measured resistance,

D is the diameter of the surface probe.

Resistivity ρ =𝑅𝐴

𝐿 (ohm-m)

Conductivity c =1

ρ (s/m)

https://en.wikipedia.org/wiki/Current_transformer

https://en.wikipedia.org/wiki/Current_transformer

https://en.wikipedia.org/wiki/Wenner_array

https://en.wikipedia.org/wiki/Wenner_array

https://en.wikipedia.org/wiki/Potential_drop

https://en.wikipedia.org/wiki/Voltage

https://en.wikipedia.org/wiki/Electric_current

https://en.wikipedia.org/wiki/Rebar

https://en.wikipedia.org/wiki/Concrete_cover

https://en.wikipedia.org/wiki/Corrosion



4.5.6 Relation to corrosion

Corrosion is an electro-chemical process. The rate of flow of the ions between the anode and

cathode areas, and therefore the rate at which corrosion can occur, is affected by the resistivity

of the concrete [5]. To measure the electrical resistivity of the concrete a current is applied to

the two outer probes and the potential difference is measured between the two inner probes.

Empirical tests have arrived at the following threshold values which can be used to determine

the likelihood of corrosion.

When ρ ≥ 120 Ω-m corrosion is unlikely

When ρ = 80 to 120 Ω-m corrosion is possible

When ρ ≤ 80 Ω-m corrosion is fairly certain

These values have to be used cautiously as there is strong evidence that chloride diffusion

and surface electrical resistivity is dependent on other factors such as mix composition and age.

The electrical resistivity of the concrete cover layer decreases due to:

Increasing concrete water content

Increasing concrete porosity

Increasing temperature

Increasing chloride content

Decreasing carbonization depth

When the electrical resistivity of the concrete is low, the rate of corrosion increases. When

the electrical resistivity is high, e.g. in case of dry and carbonated concrete, the rate of corrosion

decreases.

4.5.7 Standards:

ASTM Standard C1202-10: Standard Test Method for Electrical Indication of Concrete's

Ability to Resist Chloride Ion Penetration

AASHTO TP 95 (2011), “Standard Test Method for Surface Resistivity of Concrete’s

Ability to Resist Chloride Ion Penetration.” American Association of State Highway and

Transportation Officials, Washington, D.C., U.S.A

AASHTO Designation: T 358-151, Surface Resistivity Indication of Concrete’s Ability to

Resist Chloride Ion Penetrate ratio

5. RESULTS AND DISCUSSIONS

5.1. Corrosion condition (ASTM C 876 - 1991)

Table 4:- corrosion condition as show for finding half-cell potential method

Open circuit potential (OCP) values - m V Corrosion condition

(mV vs. SCE) (mV vs. CSE)

< - 426 < - 500 Severe condition

< - 276 < - 350 High (<90% risk of corrosion)

- 126 to – 275 - 350 to – 200 Intermediate (risk of corrosion)

> - 125 > - 200 Low (10% risk of corrosion)

https://en.wikipedia.org/wiki/Ion

https://en.wikipedia.org/wiki/Anodic

https://en.wikipedia.org/wiki/Cathodic

https://en.wikipedia.org/wiki/Resistivity

https://en.wikipedia.org/wiki/Carbonatation




5.2 NORMAL DEIONIZED WATER VS. AVERAGE VOLTAGE FOR

VARIOUS MIX OF M25 AND M30 GRADE AT DIFFERENT AGES

Table:-5 The Average Values for Corrosion Levels in Different Condition

Half-cell Potential Method Average Values

Set

no

.

Ty

pe

of

Con

cret

e

Gra

de

of

concr

ete

Ex

po

sure

co

nd

itio

n

Av

erag

e O

pen

Cir

cuit

Po

ten

tial

val

ues

(-

m V

)

Co

rro

sio

n

con

dit

ion

Av

erag

e O

pen

Cir

cuit

Po

ten

tial

val

ues

(-

m V

)

Co

rro

sio

n

con

dit

ion

Av

erag

e O

pen

Cir

cuit

Po

ten

tial

val

ues

(-

m V

)

Co

rro

sio

n

con

dit

ion

28 – days 60 -days 90- days

1 NVC

M 25 De-ionized 330V Intermediate 325V Intermediat

e 554V Severe

M30 De -ionized 354V Intermediate 215V Intermediat

e 727V Severe

2 SCC

M 25 De- ionized 347V Intermediate 327V Intermediat

e 405V Severe


e 795V Severe

3 GPC


e 544V Severe


e 871V Severe

1 NVC M25 HCL 296V Intermediate 317V

Intermediat

e 803V Severe

M30 HCL 196V Low 178V Low 772V Severe

2 SCC M25 HCL 323V Intermediate 324V

Intermediat

e 852V Severe


3 GPC M25 HCL 231V Intermediate 416V

Intermediat

e 882V Severe


1 NVC

M 25 MgSO4 317V Intermediate 318V Intermediat

e 784V Severe

M30 MgSO4 309V Intermediate 225V Intermediat

e 801V Severe

2 SCC M 25 MgSO4 312V Intermediate 456V

Intermediat

e 830V Severe

M30 MgSO4 124V Low 240V Low 829V Severe

3

GPC

M 25 MgSO4 322V Intermediate 342V Intermediat

e 881V Severe

M30 MgSO4 223V Intermediate 261V Intermediat

e 832V Severe



Figure:-8 Average Voltage for Various Mix of M25 Grade at Different Ages

Figure:-9 Average Voltage for Various Mix of M30 Grade at Different Ages

Figure:-10 Mgso4 Average Voltage For Various Mix of M25 Grade At Different Ages

0

500

1000

1500

2000

28 DAYS 60 DAYS 90 DAYS

AV

ER

AG

E V

OL

TA

GE

TIME PERIOD

NORMAL DEOIONIZED WATER (M25)

OPC M 25 SCC M25 GPC M25

0

500

1000

1500

2000

2500

3000


AV

ER

AG

E V

OL

TA

GE

TIME PERIOD

NORMAL DEIONIZED WATER(M30)


0

1000

2000

3000


AV

ER

AG

E

VO

LT

AG

E

TIME PERIOD

MgSO4 (M25)





Figure: -11 Mgso4 Average Voltage For Various Mix Of M30 Grade At Different Ages

Figure: -12 Hcl Average Voltage for Various Mix of M25 Grade at Different Ages

Figure: -13 Hcl Average Voltage For Various Mix Of M30 Grade At Different Ages

0

500

1000

1500

2000

2500

3000


AV

ER

AG

E

VO

LT

AG

E

TIME PERIOD

MgSO4 (M30)


0

500

1000

1500

2000

2500


AV

ER

AG

E V

OL

TA

GE

TIME PERIOD

HCL (M30)




Table: - 6 Electrical resistivity method average values for corrosion conditions

Electrical Resistivity Method Average Values

Set

no

.

Ty

pe

of

Con

cret

e

Gra

de

of

concr

ete

Ex

po

sure

co

nd

itio

n

Av

erag

e O

pen

Cir

cuit

Po

ten

tial

val

ues

(-

m V

)

Co

rro

sio

n

con

dit

ion

Av

erag

e O

pen

Cir

cuit

Po

ten

tial

val

ues

(-

m V

)

Co

rro

sio

n

con

dit

ion

Av

erag

e O

pen

Cir

cuit

Po

ten

tial

val

ues

(-

m V

)

Co

rro

sio

n

con

dit

ion

28 –

days

60 -days 90- days

R C R C R C

1 NVC

M 25 De-ionized 0.28 12.6 Intermediate 0.325 15.6 Intermediate 0.554 15.6 Severe

M30 De -

ionized 0.29 13.6 Intermediate 0.215 15.6 Intermediate 0.727 15.6 Severe

2 SCC

M 25 De-


M30 De -


3 GPC

M25 De -


M30 De -


1 NVC

M25 HCL 0.55 16.7 Intermediate 0.317 12.6 Intermediate 0.803 13.9 Severe

M30 HCL 0.56 17.6 Intermediate 0.178 13.9 Intermediate 0.772 18.05

Severe

2 SCC M25 HCL 0.58 18.9 Intermediate 0.324 13.6 Intermediate 0.852 19.05 Severe


3 GPC M25 HCL 0.60 21.6 Intermediate 0.416 11.8 Intermediate 0.882 21.5 Severe


1 NVC M 25 MgSO4 0.45 13.6 Intermediate 0.318 13.8 Intermediate 0.784 21.9 Severe

M30 MgSO4 0.47 13.8 Intermediate 0.225 14.8 Intermediate 0.801 32.0 Severe

2 SCC M 25 MgSO4 0.48 13.9 Intermediate 0.456 11.6 Intermediate 0.830 31.6 Severe


3 GPC M 25 MgSO4 0.48 15.6 Intermediate 0.342 14.3 Intermediate 0.881 35.6 Severe





Figure :- 14 Normal Deionized Water Average Voltage For Various Mix Of M25

Figure :- 15 Normal Deionized Water Average Voltage For Various Mix Of M30

Figure :- 16 MgSO4 Average Voltage for Various Mix of M25

0

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TIME PERIOD



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Figure :- 17 MgSO4 Average Voltage for Various Mix of M30

Figure :- 16 Hcl Average Voltage for Various Mix of M25

Figure :- 17 HCl Average Voltage For Various Mix Of M25

5. DISCUSSION

The four data integration methods used in the example of this study generally reproduce the

same tendencies, which correspond to a localized anomaly near the central reservation axis and

a localized anomaly near the exterior of the structure. However, these techniques offer different

views to help diagnose civil engineering structures. The corrosion phenomenon, a negligible

or low risk will not require vigilance in the short or medium term. A moderate risk will require

medium-term vigilance with the possibility of monitoring or additional inspections. High risk

will require short-term follow-up with the possible completion of repair work. A critical risk

0

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HCl (M25)

OPC M25 SCC M25 GPC M25

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AG

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HCl (M30)

OPC M30 SCC M30 GPC M30




will require the completion of work. The study resulted of the various average values in the

half cell potential method by having the values. The values of resistance by voltage which give

to the specimen and get the results are broadly similar to those obtained by the other integration

methods presented. The list of figure 8 to figure13 induces the corrosion values at which

properties have their increase in the levels in the different grades of concrete mix proportions.

In the electrical resistivity method values in table R indicates the resistivity and C indicates the

conductivity values, so these values various mixes having the corrosion conditions at the equal

levels. The corrosion values for the electrical resistivity method by having the resistivity and

conductivity values by the conditions given in the variable method.

6. CONCLUSION

The corrosion activity for the specimens immersed in (HCl) solution is observed more than

those compare to specimen immersed (MgSO4), (Deionized water) solution. MgSO4 is

effective to increase corrosion activity on those specimens exposed to such environment when

compared to specimen immersed in (Deionized water) and (HCl) solution. Increase in

percentage of corrosion may results in reduction of mechanical properties of steel like ultimate

strength.This project presents the results of short duration studies on corrosion. It may be

extended for studies on corrosion for long term duration

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PREDICTION OF CORROSION ACTIVITY LEVELS OF ......solutions. The corrosion levels in the specimens are assessed by measuring the potential difference between specific points of specimen

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