Page 1 of 6

European Journal of Business &

Social Sciences

Available at https://ejbss.org/

ISSN: 2235-767X

Volume 07 Issue 05

May 2019

Available online: https://ejbss.org/ P a g e | 965

Experimental Study on Electrical Indication of

Mortar's Ability to Resist Chloride ion Penetration by

Rapid Chloride ion Permeability Test

Kaalishwari .M, PG Student

Dept. of Civil Engineering

PRIST University

Thanjavur-403, India

kaalishwarice01@gmail.com

Abstract — Structures are exposed to harsh environments yet

are often expected to last with little or no repair or maintenance

for long periods of time (often 100 years or more). To do this, a

durable structure needs to be produced. For reinforced concrete

bridges, one of the major forms of environmental attack is

chloride ingress, which leads to corrosion of the reinforcing steel

and a subsequent reduction in the strength, serviceability, and

aesthetics of the structure.

This may lead to early repair or premature replacement of the

structure. A common method of preventing such deterioration is

to prevent chlorides from penetrating the structure to the level of

the reinforcing steel bar by using relatively impenetrable

concrete. The ability of chloride ions to penetrate the concrete

must then be known for design as well as quality control

purposes.

Mortar is a composite cement based material which is multi

component, micro-porous and microstructure – sensitive

construction material. Migration, particularly penetration of

chloride ion in the form of diffusion, has become the most

important topic because of its role in damaging the structures.

Resistance to damage, or in other words, the life of structures

depends upon the alkalinity (that is OH- ion concentration)of the

moist mortar.

Index Terms—RCPT test, Mortar strength

I. INTRODUCTION

Reinforced concrete structures are exposed to harsh

environments yet are often expected to last with little or no

repair or maintenance for long periods of time (often 100 years

or more). To do this, a durable structure needs to be produced.

For reinforced concrete bridges, one of the major forms of

environmental attack is chloride ingress, which leads to

corrosion of the reinforcing steel and a subsequent reduction in

the strength, serviceability, and aesthetics of the structure. This

may lead to early repair or premature replacement of the

structure.

II. COMMON METHODS

A common method of preventing such deterioration is to

prevent chlorides from penetrating the structure to the level of

the reinforcing steel bar by using relatively impenetrable

concrete. The ability of chloride ions to penetrate the mortar

must then be known for design as well as quality control

purposes.

The penetration of the mortar by chloride ions, however, is

a slow process. It cannot be determined directly in a time frame

that would be useful as a quality control measure. Therefore, in

order to assess chloride penetration, a test method that

accelerates the process is needed, to allow the determination of

diffusion values in a reasonable time. Cement mortar hollow

blocks have an important place in modern building industry.

Concrete is a composite cement based material which is

multi component, micro-porous and microstructure – sensitive

construction material. It provides fluid – flow channels

associated with ion transport and this fact causes important

phenomena like diffusion of gases, ions (particularly Cl- ions

etc.), all of which deteriorate the life expectancy of concrete

and also of rebar – embedded concrete. Migration, particularly

penetration of chloride ion in the form of diffusion, has become

the most important topic because of its role in damaging the

concrete structures.

Resistance to damage, or in other words, the life of

reinforced concrete depends on the effective passivation of the

rebar steel, which depends upon the alkalinity (that is OH- ion

concentration)of the moist concrete. The effective passivation

due to OH- ion is adversely affected by the presence of Cl- ion

in particular and carbonation of the concrete which actually

reduces the concentration of OH- ion.

In case the OH- ion concentration is lower than 11.5, the

adherence of oxide film on the rebar surface is disturbed and

Page 2 of 6

European Journal of Business &

Social Sciences

Available at https://ejbss.org/

ISSN: 2235-767X

Volume 07 Issue 05

May 2019

Available online: https://ejbss.org/ P a g e | 966

become less protective. In the case when the concrete around

the rebar is carbonated and the concentration of OH- ion gets

reduced in the pore solution, the similar result is observed. It

occurs in one or more of the following ways: as the CO2

molecule penetrate into the concrete it reacts with Ca(OH)2

with C – S – H gel, with alkali and also with Ca++ ions in pore

solution, resulting drastic decrease in the alkalinity of the pore

solution to the level of about pH 8.

Then this carbonation front progresses to the surface of the

reinforcing bar, depending on depth of the concrete cover and

on the rate of diffusion of CO2 and time.

It has been noted that films of ferric oxide are more

resistant to chloride ion than the ferrous oxide films which are

prone to soluble complex formation with

Cl-Fe(OH)2 + Cl- = [Fe Cl]x

This means, the presence of Cl- ion in the pore solution will

continuously attack Fe(OH)2 coverage on the reinforcing bar

(this is due to auto-catalytic reaction tendency of Cl- ions),

which may lead to local pitting due to the continuous and

repetitive attack. Actually there could be a competition

between passivation process (ferrous oxide film changing to

ferric oxide) and ferrous oxide film forming complex with Cl- ion (i.e. deterioration of film).

But, a higher OH- ion concentration provides the stability

of ferric oxide film. Here the role of dissolved oxygen is in

favour of normal passivation route by primarily directing

conversion of ferrous to ferric oxide.

As a result the zones of low dissolved oxygen content will

suffer pitting attack. The above analysis indicates the role of

“hydroxide to Cl-ratio” in controlling the onset of pitting

corrosion.

A. Grinder and Rapid Chloride Test (RCT)

These systems can be used to perform ASTM C 1556 and

NT BUILD 443 for apparent chloride diffusion coefficient Da,

which can afterwards be used for estimation of service life

using the solution to Fick’s Second Law of Diffusion

Fig. 1. Chloride content of each sample is determined using the RCT

B. Electrical Methods, Instrument- Prooveit Cell Method

This method involve electrical measurements, very

different values may be obtained if different water content

conditions of the concrete specimens are used. Therefore, prior

to testing the concrete, specimens should be fully water

saturated, e.g. by using a vacuum desiccator and a vacuum

pump and following the ASTM C 1202 procedure for water

saturation.

Precision coring and slicing equipment is available for

preparing test specimens. Consult the latest version of the

German Intruments catalog or visit the website for more

information

Fig. 2. The schematic of Prooveit Cell Method

C. Electrical Methods, Instrument - MERLIN

Merlin is used to measure the bulk electrical

conductivity, or its inverse, the bulk electrical resistivity, of

Page 3 of 6

European Journal of Business &

Social Sciences

Available at https://ejbss.org/

ISSN: 2235-767X

Volume 07 Issue 05

May 2019

Available online: https://ejbss.org/ P a g e | 967

saturated 100 mm diameter concrete cylinders or cores with

lengths up to 200 mm. The test is simple to perform and a

measurement is obtained within two seconds.

The term bulk is used to indicate that the

measurement is made through the specimen as opposed to a

surface-based measurement.

Fig. 3. Electrical Method- MERLIN Method

D. Electrical Methods -EXCALIBUR

Excalibur is a hand held device that also measures quickly

the electrical resistivity, however, unlike Merlin, Excalibur is

placed on the concrete surface. This surface resistivity

measurement is based on the four-probe, Wenner array,

technique. A current is applied to the two outer probes and the

voltage measured by the two inner probes

Because of its size and light weight, Excalibur is a fast,

easy-to-use and cost-effective method for quality control and

quality assurance for potential durability of concrete in

construction works, for example, by means of concrete

resistance to chloride penetration according to the classification

provided by AASHTO TP 95 standard. It provides highly

accurate readings by eliminating the error due to electrical

impedance.

Fig. 4. The Operation and Schematic of EXCALIBUR Method

III. EXPERIMENTAL PROGRAM

A. Experimental Setup

As per AASHTO T277: Electrical Indication of Concrete’s

Ability to Resist chloride Ion Penetration (Rapid Chloride

Permeability Test) (ASTM C1202):

In this test a water saturated, 50 mm thick, 100mm dia

mortar specimen is subjected to 60 V DC voltage for six hours,

as shown.

Fig. 5. RCPT Test Setup

The figure shows, that two stainless steel electrode (surface

perforated) are placed on two sides. On one side a reservoir

contains 3.0% NaCl solution (connected to –ve terminal) and

on the other side, the second reservoir contains 0.3 MNaOH

solution, its electrode is connected to +ve terminal. Originally

this test was referred to as the “Rapid Chloride Permeability

Test” (RCPT) although this test does not give permeability.

Some objections to this test are:

i) The current passed is for all ions (not just for chloride

ions)

ii) The measurements are before the steady state migration

is achieved, and

iii) A higher voltage may lead to increase in temperature,

especially for low quality concrete.

B. Strength variation with Rice Ash

Despite these limitations, many attempts have been made to

successfully correlate RCPT values with diffusion coefficients

from other tests

Mortar specimen with 10% replacement of rice ash

obtained the highest value of compressive strength, whereas,

the mortar with 30% replacement had the lowest compressive

capacity for compressive strength for both 28 and 56 days of

curing

From 4.62 N/mm2 of 0% replacement of rice ash, the

compressive strength increased by 17% at 10% replacement

but decreased by 18% at 20% replacement of rice ash and