Article

Advances in Structural Engineering

1–11
Effect of longitudinal rebar corrosion Ó The Author(s) 2016
Reprints and permissions:
on the compressive strength reduction sagepub.co.uk/journalsPermissions.nav
DOI: 10.1177/1369433216630367

of concrete in reinforced concrete ase.sagepub.com

structure

Mohsen Ali Shayanfar, Mohammad Ali Barkhordari and

Mohammad Ghanooni-Bagha

Abstract
Compressive strength reduction of concretes due to corrosion of reinforcement is one of the main reasons of failure in reinforced
concrete structure which has not been taken into account by researchers yet. Therefore, in this article, for the sake of examination of
concrete’s compressive strength reduction due to rebar corrosion, reinforced concrete cubic specimens are constructed, and then,
accelerated corrosion is applied to them. With fixing all effective parameters in compressive strength except water-to-cement ratio,
specimens with different water-to-cement ratios (0.4, 0.45, and 0.5) are constructed with various reinforcements. Finally, compressive
strength tests are performed for corroded and non-corroded specimens and reduction in compressive strength is measured under dif-
ferent degrees of corrosions.

Keywords
accelerated corrosion test, compressive strength reduction, corrosion of longitudinal reinforcement, degree of corrosion, reinforced
concrete structure

Introduction corrosion on the compressive strength of concrete,

many studies have been done on the RC structure
Corrosion of reinforcements is the most important rea- members with corroded reinforcements. But few stud-
son of fracture and failure of reinforced concrete (RC) ies, however, have addressed the effect of corrosion on
members. Poor design, weakness in construction, the compressive strength of concrete. A summary of
improper selection of materials, and, more important, researches in the literature which have investigated the
lack of accurate consideration of corrosive environ- effect of rebar corrosion in the RC structures is pre-
mental conditions during design process may cause sented in thematic categories as follows:
corrosion in RC structures (Bertolini et al., 2004;
Broomfield, 2006). This becomes more serious when
 Calculation of corrosion occurrence probability
we know that rebar corrosion and its effects have des-
and design for durability as in Rilem-130 (Sarja
tructed and failed large structures such as La
and Vesikari, 2004), DuraCrete (2000),
Concordia Bridge and Montreal Dixon Bridge of
Canada before the end of their life cycle (Ahwazi
et al., 2001; Amleh and Mirza, 1999). Thus, the main 1
Centre of Excellence for Fundamental Studies in Structural Engineering,
part of Intelligent Sensing for Innovative Structures 2
Iran University of Science and Technology, Tehran, Iran
(ISIS) projects in Canada is devoted to the structural School of civil Engineering, Iran University of Science and Technology,
Tehran, Iran
behavior analysis of RC members with corroded rein- 3
Department of civil Engineering, East Tehran Branch, Islamic Azad
forcements (Lee et al., 2000). Also, the main reason of University, Tehran, Iran
Ynys-y-Gwas bridge failure in West Glamorgan
(Woodward and Williams, 1988) is reported as reinfor- Corresponding author:
Mohammad Ghanooni-Bagha, Department of civil Engineering, East
cement corrosion. Generally, corrosion reduces the Tehran Branch, Islamic Azad University, P.O.BOX: 18735-136, postal
compressive capacity of bridge columns and piers code: 1783873531 Tehran, Iran.
(Aboutaha, 2004). In order to examine the effect of Email: ghanoonibagha@alumni.iust.ac.ir
2 Advances in Structural Engineering

Shayanfar et al. (2015), and Saassouh and retrofitting of damaged structures, due to corro-
Lounis (2012) are regarded as probabilistic sion (Lee et al., 2003), are the other research
studies and uncertainty consideration. The works about corrosion of RC structures.
study of chloride penetration into RC beams
and corrosion initiation as in Enright and Although different and relatively comprehensive
Frangopol (1998) and Duprat (2007) and the researches have been done on the corrosion and its effects
studies about concrete carbonation by Yoon on the load-bearing capacity of RC members, there are
et al. (2007) and Stewart et al. (2011) are parts not sufficient researches about the effects of developed
of this class. Estimated time calculations of cracks due to corrosion on the reduction in concrete com-
crack occurrence due to corrosion (Liu and pressive strength. Vecchio and Collins (1986) presented a
Weyers, 1998; Saad and Fu, 2013) can be con- theoretical model for calculation of compressive strength
sidered in this category. reduction based on crack model in a two-dimensional
 Experimental studies about corrosion effects on space for two-dimensional elements with shear and in-
the bond behavior between reinforcement and plane normal loadings. This model is being used in stud-
concrete such as by Amleh and Mirza (1999), ies of some researchers such as Zandi Hanjari et al.
Shayanfar et al. (2007), Coronelli and (2011) in case of corrosion of reinforcement.
Gambarova (2004), and Coronelli (2002) and According to theories of elasticity (Timoshenko and
analytical and numerical analysis such as by Goodier, 1951) and classical mechanics of materials
Shayanfar and Safiey (2008) and Berto et al. (Beer et al., 2002), when an element is subjected to a
(2008b) have studied other important parts of biaxial or triaxial stresses, the compressive stress along
corrosion effects on RC structures. the main direction may increase or decrease depending
 Damage assessment of concrete with calculation on normal stresses perpendicular to the main direction
of crack occurrence and development due to stresses. Considering that the under-corrosion elements
rebars’ corrosion and spall in tensile region of are internally subjected to stress due to the increase in
cross section is studied by some researchers such steel volume, these stresses generate micro- and macro
as Santiago Guzmán et al. (2011) and Shodja cracks in the concrete, and they reduce the compres-
et al. (2010). sive strength of concrete.
 The research for determination of reinforcement The effects of corrosion cracks on concrete com-
area decrease and its effect on reduction in struc- pressive strength and hence structure loading capacity
tures’ capacity by Val and Melchers (1997) and are considerable and clear in cases such as concrete
Enright and Frangopol (1998) and area reduction walls (especially in under-pressure parts), foundation
and steel yield stress (Du et al., 2005) are other and beams with top penetration of salt and chloride
important researches in corrosion study of RC ions, reinforced columns, and all reinforced structures.
structures. Most part of these and similar researches Therefore, due to the lack of experimental and analyti-
are about bending capacity of reinforcements. cal models regarding these effects, reduction in maxi-
 Of important and limited research about corro- mum compressive strength in terms of degree of
sion effect on capacity of RC columns is the cal- corrosion is investigated by construction of various
culation of interaction curve of moment–axial experimental specimens and application of accelerated
force of concrete columns (Tapan and corrosion to them.
Aboutaha, 2011; Wang and Liang, 2008).
 The effect of corrosion on load–displacement
Steel corrosion process
curve of beams is studied by experimental speci-
mens and finite element analysis (Al-Saidy et al., Rusting refers to iron oxidation. Iron oxidation usually
2010; Dekoster et al., 2003; Maaddawy et al., happens through reaction with iron. Rusting of iron in
2005). So some researchers such as Xue and concrete is an example of electrochemical corrosion.
Seki (2010) study the influence of longitudinal Electrochemical process includes an anode (i.e. a piece
bar corrosion on the shear behavior of RC. of metal which loses electrons easily), an electrolyte
 Corrosion effects on the behavior of large-scale (i.e. a liquid which helps electrons’ motion and is con-
structures and nonlinear behavior of structures crete here), and a cathode (i.e. the part which accepts
have been studied by Berto et al. (2008a, 2008c) electrons) (Bertolini et al., 2004). According to Shi
and Saetta et al. (2008). et al. (2011), the pH amount of concrete with Portland
 The analysis of different additives’ effects on cement is close to 13 which will be slightly more than
compressive strength and concrete corrosion 12 by adding additive materials. This degree of alkali-
characteristics (Cao and Sirivivatnanon, 1991; nity protects the rebar inside the concrete against cor-
Shi et al., 2011) and some studies about rosion by making a passive layer. Over time and by
Shayanfar et al. 3

penetration of damaging elements such as chloride or amount of increased volume of corrosion products
carbonation (CO2 penetration), the passive layer according to Nielsen (1985) and Al-Ostaz (2004) can
around the steel ruins and each iron atom loses two be seen in Table 1.
electrons. The region where the passive layer is ruined
is called anode region. With penetration of water and
air (they are present inside the concrete) and reach of Experimental work
released electrons from the metal, which moves from In order to do compression strength tests, several sets
the reinforcement to the cathode region, these materi- of square cubic specimens are made by putting reinfor-
als react according to the following equation cements inside the concrete and are compared with
control specimens. In order to do the tests and study
1
O2 + H2 O + 2e ! 2OH ð1Þ corrosion effects on compressive strength decrease in
2 normal concrete, the specimens are made with differ-
The process continues and the produced hydroxyl ent ratios of water to cement (w/c = 0.4, 0.45, and
ion moves toward the anode region and reacts with 0.5). Details of the utilized mixing plan are presented
Fe2 + ion and produces iron hydroxide Fe(OH)2. The in Table 2.
corrosion process is demonstrated in Figure 1. The utilized cement in all the plans is Portland type
Some other products are produced during corrosion II, coarse aggregate (gravel) of fractured stone with max-
occurrence. Fe(OH)2 or iron hydroxide, which is known imum nominal size of 19 mm and density of 2600 kg/
as usual rust, reacts with dissolved oxygen and produces m3. Fine aggregates (sand) are used under cement grain
hydrated ferric oxide (Fe2O3H2O) which is also called with fineness modulus of 2.65 and density of 2550 kg/
red-brown rust, black magnetite (Fe3O4), and then green m3. Water absorption of sand and cement is 0.02 and
hydrated magnetite (Fe3O4H2O) (Liu, 1996). 0.039, respectively. Based on the measured aggregate
Since the volume of rusted products is so higher moisture in every construction, necessary modifications
than iron (about 2–6.5 times), the formation of corro- of the consumed amounts have been done. Volume
sion products during time and after filling the empty ratios of sand and cement are chosen equal.
space between concrete and steel makes internal pres- A total of 10 cm 3 10 cm control cubic specimens
sure from the rebar inside the concrete and creates of normal concrete are constructed in common plastic
cracks and spalls the concrete cover (Liu, 1996). The molds which are usually used in workshops and
laboratories for compressive strength tests with pre-
sented mix plans of Table 2. After casting concrete in
the molds and vibrating the specimens, they are kept
in the molds for 24 h, and after that they are kept in
the water tank with constant temperature of about
22°C (62). Vibration is used instead of knocking in
order to avoid impact or displacement of reinforce-
ments. Table 3 shows records of compressive strength
of different constructed cubic specimens. Similar con-
trol specimens are built with rebar at the center of
Figure 1. Process of steel corrosion occurrence in concrete. mold. Also, normal cubic specimens are built with

Table 1. Amount of increased volume of the produced products during corrosion.

Corrosion products Fe FeO Fe3O4 Fe2O3 Fe(OH)2 Fe(OH)3 Fe(OH)33H2O

Volume (cm3) 1 1.8 2 2.1 3.8 4.25 6.5

Table 2. Details of used material in construction of every mixing plan in volume unit (kg/m3).

Mix no. w/c w c CA FA Air

Mix 1 0.4 152 380 919.57 901.89 0.02

Mix 2 0.45 171 380 894.87 877.67 0.02
Mix 3 0.5 190 380 870.17 53.44 0.02

w/c: water to cement; CA: coarse aggregate; FA: fine aggregates.

4 Advances in Structural Engineering

Table 3. Average strength of normal cubic specimen with non-corroded reinforcement (MPa).

w/c Rebar f 9c (7) f 9c (28) f 9c (42) f 9c (90)

0.4 No bar 28.5 45 47 49.5

[ 10 28 44 48.5 51
0.45 No bar 23.5 38 40 42
[ 10 22 37 40.5 43
0.5 No bar 18 30.5 31.5 33
[ 10 17 29 31.5 34

w/c: water to cement.

similar plans and are located in the water–salt solution

of 5%. Compressive strength of specimens inside the
NaCl solution of 5% does not have tangible difference
with specimens inside the water.
According to Table 3, the specimen strength with
rebar does not differ much with the specimen without
rebar in no-corrosion case in the life of 28 days. Over
time, the strength of the specimens with rebar is slightly
higher than the specimens without rebar.

Specimens with reinforcement for applying

accelerated corrosion
Figure 2. Schematic diagram of electrochemical corrosion.
To calculate the compressive strength reduction of
cubic concrete specimens, steel reinforcements with
diameters of 6, 10, 12, and 16 mm are placed at the solution density is considered 5%, while in Yalciner
center of 100 mm 3 100 mm square cubic molds and et al. (2012) the preparation time is 4 days and the
accelerated corrosion is applied to them. The rebars solution density is 3.5%. Fang et al. (2006a) prepared
are located at the middle of the specimen and the effec- the specimens for 28 days in water–salt solution of 5%
tive corrosion depth is considered as twice the cover density after the construction. In this study, the speci-
(i.e. specimen dimensions). mens were kept in the tank containing water–salt solu-
tion of 3.5% density with previously mentioned
constant temperature for 4 days and were prepared for
Rebars’ preparation before construction applying accelerated corrosion. According to Figure 2,
In order to apply even pressure and to prevent stress direct current is applied to the specimens to accelerate
concentration and load distribution differences between the process. For every placed specimen in the con-
concrete and steel during loading, the reinforcements are tainer of sodium chloride solution of 5%, the positive
cut to have completely smooth cross section. The reinfor- pole of direct current source is connected to the inside
cements are cut slightly smaller than 100 mm to lie easily reinforcement by a wire and the negative pole is con-
inside the mold. For firm keeping, a small piece of paper nected to the copper plate inside the water–salt solu-
is placed at one end of the rebar. Also, the reinforce- tion by a wire in such a way that the inside bar is used
ments are weighed accurately before putting them inside as anode and the copper plate inside the solution is uti-
the mold to calculate the degree of corrosion by weight- lized as cathode.
ing them after corrosion applying and testing. In different references, various amounts are stated
for the current and voltage of the source. An adjusta-
ble current with constant voltage of 60 V and current
Applying accelerated corrosion to the specimens of 0–5 A is used by Yalciner et al. (2012). Fang et al.
Accelerated electrochemical corrosion method is used (2006a, 2006b) applied electrolyte corrosion process by
to apply corrosion. The specimens must be prepared voltage regulation in terms of current from 0 to 20 A.
before the accelerated corrosion application. The solu- In this study, the current, which is in direct relation-
tion density and preparation time are variable in dif- ship with degree of corrosion, is kept constant, about
ferent sources. In Kivell et al. (2011) and Fang et al. 0.2 A, by the direct current source and the voltage is
(2004), the preparation time is 3 days and water–salt adjustable.
Shayanfar et al. 5

It must be paid attention that during the tests, the end insulator performance is estimated during test by
end part of the rebar and generally the concrete bot- checking current variations and necessary modifica-
tom must be covered with adhesive to prevent short tions and insulator replacement are done if required.
circuit. Then, its top must be covered with melted can- To calculate accurately the degree of corrosion and
dle. In this case, current flow will be through the con- mass decrease in reinforcements, the bars can be taken
crete and the passing current will be dependent on the out of the concrete easily by applying pressure to the
concrete strength against chloride ions’ penetration. In cubic specimens in the direction normal to the bar’s
this system, the chloride ions will pass according to the length; it is done after compressive strength test of cor-
described mechanism in Figure 1 through concrete and roded specimens. According to the standard ASTM
reach the bar and create corrosion. G1-03 (2003), the reinforcements are brushed and HCl
is used to clean their surface chemically before weight-
ing them. Finally, the available rebar weight is com-
Calculation of degree of corrosion pared to the initial one and the exact degree of
Theoretical mass reduction of bars during accelerated corrosion is determined based on equation (3)
corrosion is calculated proportional to corrosion flow
and based on Faraday law, equation (2). Time estima- Cw (real mass loss) =
tion calculations corresponding to the considered cor- mbase (weight before test)  mremain (weight after test)
3 100
rosion based on this equation are used for initial mbase (weight before test)
planning and tests’ timing ð3Þ
mt (mass loss) = Figure 3 shows the summary of all tests performed
t(s) 3 I(A) 3 M(g=mol for iron = 55:847) ð2Þ in this research in order to calculate the reduction in
compressive strength versus degree of corrosion.
z(for iron = 2) 3 F(coulomb=mol = 96, 487)
where mt is the mass loss, I is the current, M is the
Test results
molar mass of element, z is the valency of the element,
t is the time, and F is Faraday’s constant. Time is the In this section, first the important factors affecting the
only unknown parameter for calculation of pre- compressive strength of concrete are considered.
determined corrosion amount when keeping I constant Except w/c ratio which is the most important para-
and known in equation (2) and can be obtained easily. meter, all other parameters and conditions are held
Passing current from each specimen during short inter- same and constant for all specimens.
vals is measured and recorded based on the acquired The temperature of the specimen is conversely pro-
amount from the direct current source to change vol- portional to the compressive strength of concrete, dur-
tage for keeping current constant if needed. Also, the ing curing or the test was held at about 20°C constant

Figure 3. Schematic flowchart of test procedure.

6 Advances in Structural Engineering

Figure 4. Compressive strength test setup and corroded specimen.

temperature. The curing conditions of non-corroded aforementioned, the amount of corrosion degree is
and corroded specimens are also considered the same. determined using mass reduction of bar in specimens.
In addition, non-corroded and corroded specimens are In every construction, plus every specimen for
also tested at the same time and same age, and based applying corrosion, the base specimen is constructed
on this, by comparing the strength reduction of the for comparison and determination of the percentage of
corroded specimen with the non-corroded one (with compressive reduction in different degrees of corrosion
non-dimensioning of corrosion), the influence of based on weighting method. The values obtained and
strength increasing with age enhancement is neutra- their details are reported for every construction test in
lized in calculations. The dimensions of cubic speci- Tables 4 to 6. Although the calculation of theoretical
mens are considered as 100 mm 3 100 mm. The mass reduction based on equation (2) is done for tests’
loading rate which is directly proportional to the com- timing and is not the aim of this study, for the base
pressive strength for all specimens is kept the same. mix concrete with w/c = 0.45, real degree of corrosion
Moreover, the amount, dimension, shape, and gener- and theoretical degree of corrosion are recorded based
ally grading of the used aggregates (despite of being on equation (3). According to Table 4, equation (2)
uniform and almost large) and also the amount and with respect to equation (3) usually is overestimated
type of the used cement are also held constant in all for calculating the amount of mass loss.
specimens. Air of concrete which is conversely propor- According to Table 4, for the specimen with w/
tional to compressive strength is fixed at about 0.02 in c = 0.45, the following equation illustrating the effect
all specimens. of reinforcement corrosion on compressive strength
After construction of specimens with w/c = 0.4, reduction is obtained using least square regression
0.45, and 0.5 and applying corrosion to them, the com- method
pressive strength reduction is determined relative to
the base specimens. Compressive strength test is car- l = 2:288Cw  1:733 ð4Þ
ried out for both corroded and non-corroded speci- where l is the percentage of compressive strength
mens based on the standard BS 1881:PART116 (1983) reduction and Cw is the corrosion level. The correla-
as shown in Figure 4. Then, according to what tion coefficient (by eliminating rows 6, 7, and 10 that
Table 4. Relationship between compressive strength of concrete with strength of 38 MPa in various corrosion levels (w/c = 0.45).

No. Specimen Specimen bar Base Weight of rebar Cw % Cw % (real) Day of Mean of f 9c for f 9c from Percentage of
size weight (g) after corrosion (faraday) test base specimen test reduction in f 9c (l)
Shayanfar et al.

1 S10 3 10-base No bar – Base specimen – – 28 38 38 0

2 S10 3 10-base [ 10 – No corrosion 0 0 28 37.5 37.5 0
3 S10 3 10-[ 10 [ 10 63.7 61.76 5.31 3.04 42 40.5 38.6 4.69
4 S10 3 10-[ 10 [ 10 64.35 63.01 3.86 2.08 42 40.5 38.6 4.69
5 S10 3 10-[ 10 [ 10 64.4 62.15 4.41 3.50 90 43 40.1 6.74
6 S10 3 10-[ 10 [ 10 63.76 61.94 6.11 2.85 90 43 35.8 16.74
7 S10 3 10-[ 10 [ 10 64.12 60.76 8.56 5.24 90 43 41.9 2.56
8 S10 3 10-[ 10 [ 10 63.48 59.83 6.16 5.75 90 43 37.6 12.56
9 S10 3 10-F 12 F 12 85.36 81.68 4.84 4.31 90 44 41.4 5.91
10 S10 3 10-F 12 F 12 86.49 82.88 9.34 4.17 90 44 33.4 24.09
11 S10 3 10-F 12 F 12 85.91 79.72 6.2 7.21 90 44 37.2 15.45
12 S10 3 10-[ 16 [ 16 159.27 152.12 7.73 4.49 90 45 41.7 7.33

w/c: water to cement.

Table 5. Compressive strength of cubic specimens with strength of 45 MPa in various corrosion levels (w/c = 0.4).

No. Specimen Specimen As_basic Base Weight of rebar Cw % Day of Mean of f 9c for base f 9c from test Percentage of
bar size weight (g) after corrosion test specimen reduction in f 9c (l)

1 S10 3 10-base No bar – – Base specimen – 28 45 45 –

2 S10 3 10-[ 10 [ 10 0.785 62.85 No corrosion 0 28 44 44 0
3 S10 3 10-[ 10 [ 10 0.785 63.04 61.93 1.76 42 48.5 47.2 2.68
4 S10 3 10-[ 10 [ 10 0.785 63.27 61.76 2.39 42 48.5 46.4 4.33
5 S10 3 10-[ 10 [ 10 0.785 63.24 60.81 3.84 90 50.9 33.3 34.58
6 S10 3 10-[ 10 [ 10 0.785 64.91 59.52 8.30 90 50.9 39.9 21.61
7 S10 3 10-F 12 F 12 1.131 85.01 83.14 2.20 42 49.2 46.6 5.28
8 S10 3 10-F 12 F 12 1.131 85.19 80.19 5.87 90 52.1 37.2 28.60
9 S10 3 10-F 12 F 12 1.131 86.49 80.31 7.15 90 52.1 43.4 16.70
10 S10 3 10-F 12 F 12 1.131 86.08 82.53 4.12 90 52.1 47.9 8.06

w/c: water to cement.

7
8 Advances in Structural Engineering

reduction in f 9c (l)
have high dispersion) equals 0.89 (R2 = 0.89). In the
case that all data are considered, we have R2 = 0.05,
Percentage of

which is unacceptable.
After computing l, the reduced compressive

14.37
21.70

26.29
13.14
1.90
6.67
9.09

4.92

6.30
strengths can be calculated as follows
0
0

f 9c corr = (1  l)f 9c ð5Þ

f 9c from test

A summary of different degrees of corrosion results

with various reinforcements in specimens with w/c ratio
of 0.4 and 0.5 is presented in Tables 5 and 6.
30.5

30.9
29.4
31.0
29.2
26.7
30.9
25.8
30.4
34.2
29

Table 5 is given for the specimens with w/c = 0.4.

Equation (6) is obtained base on using least square
Mean of f 9c for

regression method in order to demonstrate the effect

base specimen

of reinforcement corrosion on reduction in compres-

sive strength
30.5

31.5
31.5
34.1
34.1
34.1
32.5

36.5
29

35
35

l = 2:72Cw  1:98 ð6Þ

The correlation coefficient (by eliminating rows 5

Day of test

and 8 that have high dispersion) equals 0.98

Table 6. Compressive strength of cubic specimens with strength of 30 MPa in various corrosion level (w/c = 0.5).

(R2 = 0.89). In the case that all data are considered,

we have R2 = 0.32, which is unacceptable.
28
28
42
42
90
90
90
42
90
90
90

Table 6 is given for the specimens with w/c = 0.5

and equation (7) is obtained in order to calculate com-
Cw %

1.66
2.79
3.89
3.60
8.84
2.69
2.83
6.45
3.52

pressive strength reduction due to the effect of reinfor-

–
0

cement corrosion
Weight of rebar

l = 2:576Cw  1:876 ð7Þ

after corrosion

Base specimen
No corrosion

The correlation coefficient (by eliminating rows 6

154.53
62.35
62.37
60.26
60.84
58.24
83.85
83.05
81.97

and 9 that have high dispersion) equals 0.97

(R2 = 0.89). In the case that all data are considered,
we have R2 = 0.26, which is unacceptable.
The percentage of compressive strength reduction
weight (g)

versus degree of corrosion is presented in Figure 5 for

160.16
64.16

63.11
63.89
86.17
85.47
87.62
63.4

62.7

all three concrete types. It should be mentioned that

Base

the aforementioned formulas were obtained for com-

–
–

mon concretes with presented mixed designs and the

used materials’ properties.
As_basic

According to Tables 4 to 6 and Figure 5, in the same

0.785
0.785
0.785
0.785
0.785
0.785
1.131
1.131
1.131
2.011

corrosion degree, in the specimens with higher com-

–

pressive strengths more decrease in compressive

strengths is observed. There are two reasons for this
Specimen

observation. First, in the specimens with higher com-

bar size

No bar
[ 10
[ 10
[ 10
[ 10
[ 10
[ 10

[ 16
F 12
F 12
F 12

pressive strengths, the behavior of the material is more

brittle. Second, according to mixed design and the size
of course aggregation utilized for construction of speci-
mens, the mortar volume of the concrete is reduced.
10-[ 10
10-[ 10
10-[ 10
10-[ 10
10-[ 10
10-[ 10

10-[ 16
10-F 12
10-F 12
10-F 12
10-base

This leads to undesirable honeycombing in the har-

w/c: water to cement.
Specimen

dened concrete. However, if the graining is good, and

3
3
3
3
3
3
3
3
3
3
3

there is no honeycombing, the probability of strength

S10
S10
S10
S10
S10
S10
S10
S10
S10
S10
S10

reduction is lower in similar degrees of corrosion at

specimens with higher strength, because the tensile
strength increases which is a function of compressive
No.

10
11

strength. Studying this factor and other effective

1
2
3
4
5
6
7
8
9
Shayanfar et al. 9

Figure 5. Percentage of compression strength reduction versus degree of corrosion.

factors on compressive strength is impossible without Declaration of Conflicting Interests

building and testing of various specimens. So, accord- The author(s) declared no potential conflicts of interest with
ing to the test result and Figure 5, the amount of con- respect to the research, authorship, and/or publication of this
crete compressive strength reduction is higher by article.
increasing the corrosion level or degree of corrosion.
Funding
Conclusion The author(s) received no financial support for the research,
authorship, and/or publication of this article.
In this article, for the first time, the compressive
strength reduction of concrete due to the corrosion of References
reinforcements is investigated using the experimental
specimens. For this purpose, several cubic specimens Aboutaha RS (2004) Guide for Maintenance and Rehabilita-
tion of Concrete Bridge Components with FRP Composites:
with different w/c ratios containing rebar were tested
Research into Practice. Albany, NY: TIRC and NYSDOT.
to determine final compressive strength of RC under Ahwazi BBN, Amleh L and Mirza MS (2001) Effect of cor-
corrosion of reinforcements. rosion on bond strength of reinforcing bars in concrete.
Considering the conducted experiments, the amount In: Proceedings of the 1st international conference on con-
of compressive strength reduction (l) is directly pro- crete and development, Tehran, Iran, 30 April–2 May
portional to the increment of corrosion degree (Cw). A 2001, pp. 309–330. Tehran, Iran: The Building and Hous-
correlation was proposed for the calculation of com- ing Research Center of IRAN.
pressive strength reduction with respect to corrosion Al-Ostaz A (2004) Diagnostic evaluation and repair of dete-
degree for three types of concretes with w/c = 0.4, riorated concrete bridges. Final report, The University of
0.45, and 0.5. According to the results obtained, for Mississippi, University, MS, December.
the concretes with relatively large uniform graining, it Al-Saidy AH, Al-Harthy AS, Al-Jabri KS, et al. (2010) Struc-
tural performance of corroded RC beams repaired with
was observed that the corrosion degree in concretes
CFRP sheets. Composite Structures 92: 1931–1938.
with higher strength (i.e. lower w/c) is lower at the Amleh L and Mirza MS (1999) Corrosion influence on bond
same values of l and vice versa. Moreover, in con- between steel and concrete. ACI Structural Journal 96(3):
cretes with lower strength (w/c = 0.5), the amount of 415–423.
compressive strength reduction was lower in similar ASTM G1-03 (2003) Standard practice for preparing, clean-
corrosion degree; and in concretes with more strength ing, and evaluating corrosion test specimens (American
or less w/c ratio (w/c = 0.4), the amount of compres- Society for Testing and Materials).
sive strength reduction in similar corrosion degree rela- Beer FP, Johnston ER and Dewolf JT (2002) Mechanics of
tive to concrete with w/c = 0.45 was found to be Materials. 3rd ed. New York: McGraw-Hill.
higher. Berto L, Saetta A, Simioni P, et al. (2008a) Non linear static
analyses of RC frame structures: influence of corrosion on
10 Advances in Structural Engineering

seismic response. In: Proceedings of the 8th WCCM8—5th Guzmán S, Gálvez JC and Sancho JM (2011) Cover cracking
ECCOMAS, Venice, 30 June–5 July. of reinforced concrete due to rebar corrosion induced by
Berto L, Simioni P and Saetta A (2008b) Numerical model- chloride penetration. Cement and Concrete Research
ling of bond behaviour in RC structures affected by rein- 41(8): 893–902.
forcement corrosión. Engineering Structures 30(5): Kivell A, Palermo A and Scott A (2011) Effects of bond
1375–1385. deterioration due to corrosion in reinforced concrete. In:
Berto L, Vitaliani R, Saetta A, et al. (2008c) Seismic assess- Proceedings of the 2011 Pacific conference on earthquake
ment of existing RC structures affected by degradation engineering (PCEE), Auckland, New Zealand, 14–16
phenomena. Structural Safety 31: 284–297. April, pp. 81–89. Wellington, New Zealand: New Zealand
Bertolini L, Elsener B, Pedeferri P, et al. (2004) Corrosion of Society for Earthquake Engineering Inc.
Steel in Concrete: Prevention, Diagnosis, Repair. Wein- Lee C, Bonacci JF, Thomas MD, et al. (2000) Accelerated
heim: Wiley-VCH Verlag GmbH & Co. KGaA. corrosion and repair of reinforced concrete columns using
Broomfield JP (2006) Corrosion of Steel in Concrete: Under- carbon fibre reinforced polymer sheets. Canadian Journal
standing, Investigation and Repair. 2nd ed. Abingdon: of Civil Engineering 27(5): 941–948.
Taylor & Francis e-Library. Lee HS, Kage T, Noguchi T, et al. (2003) An experimental
BS 1881:Part 116 (1983) Method for Determination of Com- study on the retrofitting effects of reinforced concrete col-
pressive Strength of Concrete Cubes. London: British Stan- umns damaged by rebar corrosion strengthened with carbon
dards Institution. fiber sheets. Cement and Concrete Research 33: 563–570.
Cao HT and Sirivivatnanon V (1991) Corrosion of steel in Liu Y (1996) Modeling the time-to-corrosion cracking of the
concrete with and without silica fume. Cement and Con- cover concrete in chloride-contaminated reinforced concrete
crete Research 21: 316–324. structures. PhD Thesis, Department of Civil Engineering,
Coronelli D (2002) Corrosion cracking and bond strength Virginia Polytechnic Institute and State University,
modeling for corroded bars in reinforced concrete. ACI Blacksburg, VA.
Structural Journal 99(3): 267–276. Liu Y and Weyers RW (1998) Modelling the time-to-
Coronelli D and Gambarova P (2004) Structural assessment corrosion cracking in chloride contaminated reinforced
of corroded reinforced concrete beams: modeling guide- concrete structures. ACI Materials Journal 95(6): 675–681.
lines. Journal of Structural Engineering: ASCE 130(8): Maaddawy TE, Soudki K and Topper T (2005) Analytical
1214–1224. model to predict nonlinear flexural behaviour of corroded
Dekoster M, Buyle-Bodin F, Maurel O, et al. (2003) Model- reinforced concrete beams. ACI Structural Journal 102(4):
ing of flexural behavior of RC beams subjected to loca- 550–559.
lized and uniform corrosion. Engineering Structures 25: Nielsen A (1985) Durability in BetonBogen. Aalborg: Aalborg
1333–1341. Cement Company, pp. 200–243.
Du YG, Clark LA and Chan AHC (2005) Residual capacity Saad T and Fu CC (2013) Determining remaining strength
of corroded reinforcing bars. Magazine of Concrete capacity of deteriorating RC bridge substructures.
Research 57(3): 135–147. Journal of Performance of Constructed Facilities 29(5):
Duprat F (2007) Reliability of RC beams under chloride 04014122.
ingress. Construction and Building Materials 21(8): Saassouh B and Lounis Z (2012) Probabilistic modeling of
1605–1616. chloride-induced corrosion in concrete structures using
DuraCrete R17 (2000) DuraCrete Final Technical Report, first-and second-order reliability methods. Cement and
Document BE95-1347/R17, May 2000, The European Concrete Composites 34(9): 1082–1093.
UnionBrite EuRam III, DuraCrete–Probabilistic Perfor- Saetta A, Simioni P, Berto L, et al. (2008) Seismic response
mance based Durability Design of Concrete Structures, of corroded R.C. structures. In: Walraven JC and Stoel-
includes General Guidelines for Durability Design and horst D (eds) Tailor Made Concrete Structures. London:
Redesign, Document BE95-1347/R15, February 2000, Taylor & Francis Group, p. 228.
CUR, Gouda, the Netherlands. Sarja A and Vesikari E (2004) Durability design of concrete
Enright MP and Frangopol DM (1998) Probabilistic analysis structures, vol. 14. Report of RILEM Technical Commit-
of resistance degradation of reinforced concrete bridge tee 130-CSL
beams under corrosión. Engineering Structures 20(11): Shayanfar MA and Safiey A (2008) A new approach for
960–971. nonlinear finite element analysis of reinforced concrete
Fang C, Gylltoft K, Lundgren K, et al. (2004) Corrosion structures with corroded reinforcements. Computers and
influence on bond in reinforced concrete. Cement and Concrete 5(2): 155–174.
Concrete Research 34: 2159–2167. Shayanfar MA, Barkhordari MA and Ghanooni-Bagha M
Fang C, Gylltoft K, Lundgren K, et al. (2006a) Effect of cor- (2015) Probability calculation of rebars corrosion in rein-
rosion on bond in reinforced concrete under cyclic load- forced concrete using CSS algorithms. Journal of Central
ing. Cement and Concrete Research 36: 548–555. South University 22: 3141–3150.
Fang C, Lundgren K, Plos M, et al. (2006b) Bond behaviour Shayanfar MA, Ghalehnovi M and Safiey A (2007) Corro-
of corroded reinforcing steel bars in concrete. Cement and sion effects on tension stiffening behavior of reinforced
Concrete Research 36: 1931–1938. concrete. Computers and Concrete 4(5): 403–424.
Shayanfar et al. 11

Shi X, Yang Z, Liu Y, et al. (2011) Strength and corrosion Wang XH and Liang FY (2008) Performance of RC columns
properties of Portland cement mortar and concrete with with partial length corrosion. Nuclear Engineering and
mineral admixtures. Construction and Building Materials Design 238(12): 3194–3202.
25(8): 3245–3256. Woodward RJ and Williams FW (1988) Collapse of Ynys-y-
Shodja HM, Kiani K and Hashemian A (2010) A model for Gwas bridge: West Glamorgan. Proceedings of the Institu-
the evolution of concrete deterioration due to reinforce- tion of Civil Engineers, Part 1: Design and Construction 84:
ment corrosión. Mathematical and Computer Modelling 635–669.
52(9): 1403–1422. Xue X and Seki H (2010) Influence of longitudinal bar corro-
Stewart MG, Wang X and Nguyen MN (2011) Climate sion on shear behavior of RC beams. Journal of Advanced
change impact and risks of concrete infrastructure dete- Concrete Technology 8(2): 145–156.
rioration. Engineering Structures 33(4): 1326–1337. Yalciner H, Eren O and Sensoy S (2012) An experimental
Tapan M and Aboutaha RS (2011) Effect of steel corrosion study on the bond strength between reinforcement bars
and loss of concrete cover on strength of deteriorated RC col- and concrete as a function of concrete cover, strength and
umns. Construction and Building Materials 25: 2596–2603. corrosion level. Cement and Concrete Research 42(5):
Timoshenko S and Goodier JN (1951) Theory of Elasticity. 643–655.
New York: McGraw-Hill, p. 412. Yoon IS, Copuroglu O and Park KB (2007) Effect of global
Val DV and Melchers RE (1997) Reliability of deteriorating climatic change on carbonation progress of concrete.
RC slab bridges. Journal of Structural Engineering: ASCE Atmospheric Environment 41: 7274–7285.
123(12): 1638–1644. Zandi Hanjari K, Kettil P and Lundgren K (2011) Analysis
Vecchio F and Collins MP (1986) The modified compression of the mechanical behavior of corroded reinforced con-
field theory for reinforced concrete elements subjected to crete structures. ACI Structural Journal 108(5):
shear. ACI Structural Journal 83(2): 219–231. 532–541.