International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 609–616, Article ID: IJCIET_10_04_063
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJCIET&VType=10&IType=4
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
Scopus Indexed
EXPERIMENTAL INVESTIGATION OF
ANTICORROSIVE REBAR COATING OVER
MILDSTEEL ROD USING PLASTIC WASTES
J. Jeyanthi
Assistant Professor, Department of Civil Engineering,
Mepco Schlenk Engineering College, Sivakasi-626005, Tamilnadu, India
ABSTRACT
The objective of this project is to discover a solution for controlling the corrosion
in steel bars. Among all waste plastics PET bottles, poly-ethene bags are playing the
major role in pollution. Thus an attempt has been made to reduce corrosion in rebar
by using waste plastics. In this project used Polyethylene terephthalate [PET] bottles
have been chosen among all plastics, experimental investigation was carried out with
mild steel rods of 6 mm diameter and average length of 50mm coated with PET.
Corrosion tests were conducted on the treated specimens at 700 ºC. Pore resistance
(Rp), Resistance of the MS sample(Rct), corrosion current (Icorr ) were found to find
the corrosion rate. From weight loss method, it was concluded that the treated
samples can be effectively used against corrosion in concrete which is basic in nature
(pH: 11- 12.5) and also for off shore works. The SEM image of treated MS sample
shows the coating thickness varies from 1.19 micron – 3.37 micron.From EIS
experiment, it was found that optimum temperature to induce a corrosion resistant
property to the rebar is 700 ºC and optimum weight ratio of rebar and PET is 1:1.
Key words: Corrosion, Mild steel, PET bottles, EIS.
Cite this Article: J. Jeyanthi, Experimental Investigation of Anticorrosive Rebar
Coating Over Mildsteel Rod Using Plastic Wastes, University of Jordan, International
Journal of Civil Engineering and Technology 10(4), 2019, pp. 609–616.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=4
1. INTRODUCTION
In critical corrosion conditions, the durability of the structure can only be guaranteed by
providing additional protection to the steel reinforcement. Behzadnasa et al found that
addition of the spherical ZrO2 nano clay particles improves the corrosion performance of steel
and improves the barrier properties and ohmic resistance [1].Chavan et al analyzed the
corrosion effect of cold sprayed zinc coatings over steel rods at a temperature of 150 °C,
found better improvement in properties of steel [2].Esfahani et al found that sprayed
aluminum coatings can sustain steel structures against corrosion in aqueous solutions
[3].Ohtsuka and Toshiaki experimentally found that steel coated with polimer was inactive for
about 200 h in 3.5% sodium chloride solution without formation of corrosion
http://www.iaeme.com/IJCIET/index.asp
609
editor@iaeme.com
J. Jeyanthi
products[4].Poursaee and Amir experimentally found that reduction in passivation of steel
bars is caused by either chloride ions or carbonation exposure induces the active corrosion of
steel bars[5].Shi et al investigated the corrosion behavior of steel beams and found that plate
thickness is an important factor influencing the corrosion behavior over geometry[6].Tang et
al investigated the corrosion behavior of enamel coated steel bars, found that pure and double
enamel coatings can considerably recover corrosion resistance in salt environment[7].Umoren
et al investigated the corrosion behavior of mild steel under methanol extract acid medium
and found that extract was found to be better inhibitor, reduces the corrosion of mild steel
[8].Ye, Chen-Qing et al proved that EIS measurement of corrosion behavior for reinforcement
steel in simulated carbonated concrete pore (SCCP) solution was best with the LPR and SEM
measurements [9].Zavareh et al investigated the ceramic oxide coated steel structures and
found improved in corrosion resistance by noticeable improvement [10].Thus investigation of
corrosion in mild steel is important for environmental protection.
1.1. Corrosion Preventive Methods
By retarding either the anodic or cathodic reactions the rate of corrosion can be reduced. This
can be achieved in several ways:
A. Conditioning the Metal
(a) Coating the metal:
1. Another metal, e.g. zinc or tin coatings on steel,
2. A protective coating derived from the metal itself, e.g. aluminium oxide on “anodised”
aluminium,
3. organic coatings, such as resins, plastics, paints, enamel, oils and greases.
(b) Alloying the metal to produce a more corrosion resistant alloy, e.g. stainless steel.
B. Conditioning the Corrosive Environment
(a) Corrosion Inhibitors
Corrosion inhibitor is a Chemical additive, which when added to a corrosive aqueous environment
reduces the rate of metal wastage. It can function in one of the following ways:
1. Anodic inhibitors.
2. Cathodic inhibitors.
3. Adsorption type corrosion inhibitors.
4. Mixed inhibitors- combination of anodic and cathodic inhibitors.
1.2. PET
Polyethylene terephthalate commonly abbreviated PET. PET is a thermoplastic polymer resin
of the polyester family and is used in synthetic fibers, beverage, food and other liquid
containers. Depending on its processing and thermal history, polyethylene terephthalate may
exist both as an amorphous (transparent) and as a semi-crystalline polymer. The semi
crystalline material might appear transparent (particle size < 500 nm) or opaque and white
(particle size up to a few microns) depending upon its crystal structure and particle size. Its
monomer (bis-β-hydroxy-terephthalate) can be synthesized by the esterification reaction
between terephthalic acid and ethylene glycol with water as a by-product, or by transesterification reaction between ethylene glycol and di-methyl terephthalate with methanol as a
by-product. Polymerization is through a poly-condensation reaction of the monomers (done
immediately after esterification/trans-esterification) with water as the by-product.
http://www.iaeme.com/IJCIET/index.asp
610
editor@iaeme.com
Experimental Investigation of Anticorrosive Rebar Coating Over Mildsteel Rod Using Plastic Wastes
PET consists of polymerized units of the monomer ethylene terephthalate, with repeating
C10H8O4 units.
2. SAMPLE PREPARATION PROCEDURE
The sample preparation was carried out using an alumina crucible which can withstand upto
1750ºC.The 6 mm diameter Mild Steel bar is cut into 50mm length to fit inside the crucible.
The MS bar was initially washed with soap solution and cleaned with distilled water and then
it was allowed to dry in sunlight for 60 minutes. Waste PET bottles were collected and it was
cut into small pieces. Similar to MS bar, small pieces of PET also washed and dried. The
experiment was done with various ratios like 1:1 and 1:0.5 of MS bar and PET respectively in
terms of weight. Hence MS bar and PET are weighed before the experiment. Then the small
PET pieces were wrapped around the 50mm length MS bar and placed inside the crucible and
closed with a lid.
Table 1 Sample preparation details
Sample Details
Length of MS rod
Diameter of MS rod
Surface are of MS rod
Unit
mm
mm
mm2
Weight before testing
grams
Plastic used
Temperature
Ratio [Steel : plastic]
Duration
Residue[ash]
grams
ᵒC
-minutes
grams
Weight after testing
grams
Sample1
50
6
99.943
12.40
12.06
11.57
36.03
600
1:1
30
2.88
12.41
12.07
11.58
Sample2
50
6
99.943
11.46
11.47
12.07
35.00
400
1:1
30
3.5
11.48
11.49
12.09
Sample3
50
6
99.943
11.79
11.38
12.10
35.27
700
1:1
30
2.82
11.80
11.39
12.11
Sample4
50
6
99.943
10.82
11.56
12.18
17.38
700
1:0.5
30
1.39
10.83
11.57
12.19
Sample5
50
6
99.943
13.17
12.64
11.95
18.88
600
1:0.5
30
1.51
13.18
12.65
11.96
The total arrangement was then kept inside the induction furnace. To determine the
optimum temperature, the experiment was carried out over five samples as shown in table. 1
at various temperatures like 700ºC, 600ºC and 400ºC. The total setup was maintained at
respective temperatures in the furnace for duration of 30 minutes. Then the setup was allowed
to cool at room temperature. After that the treated sample was again weighed to observe the
weight difference. Numerous samples have been prepared with the particular ratio and
temperature. Finally the tests like weight loss, EIS were conducted on the sample and the
results were tabulated.
3. EXPERIMENTAL METHODS
3.1. Weight Loss Method
For weight loss method six mild steel (MS) rod sample coated with PET of diameter 6mm and
length 50mm were taken. Out of six sample three sample were treated at 700ᵒC with the ratio
1:1 (MS : PET) and remaining three sample were untreated. All samples are washed
thoroughly with soap solution and distilled water and dried in sunlight for 30minutes. Initially
all the MS samples are weighed. Two set of 200 ml Acidic medium of 0.1N HCL, Base
http://www.iaeme.com/IJCIET/index.asp
611
editor@iaeme.com
J. Jeyanthi
medium of 0.1N NaOH and Salt solution of 0.1N Nacl were prepared and their pH values
were also noted. Both treated and untreated MS samples were immersed in corresponding
mediums for 24 hours. Then both the samples were washed with soap solution, distilled water
and was sun dried. Weight of each sample after immersion is weighed and pH of the medium
were measured after immersion. Summary of weight loss method is shown in Table 2.
Corresponding percentage of weight loss are calculated by using the formulae:
%Weight loss =
Where,
W1 = Weight before immersion, W2 = Weight after immersion.
Corresponding corrosion rate per year are calculated by using the formula:
Corrosion rate per year (mm/yr) = 87.6
Where,
W = difference in weight in mg
D = density of steel (7.75 g/cm3)
a = area of steel (9.9943cm2)
T = duration (24hours)
Table 2 Summary of weight loss method
Normality
Medium
0.1N HCl
0.1N HCl
0.1N
NaOH
0.1N
NaOH
Acid
Acid
pH
value
(before
test)
1.23
1.28
Base
12.01
11.44
12.127
12.03
11.53
7.54
7.52
Sample
@
700ºC
Nature of
sample
1
2
Untreated
Treated
3
Untreated
4
Treated
5
Untreated
0.1N NaCl
6
Treated
0.1N NaCl
Base
Salt
solution
Salt
solution
pH
value
(after
test)
1.19
1.24
Weight
before
test W1
[g]
11.689
12.144
Weight
after test
W2
[g]
11.396
11.81
Figure 1
http://www.iaeme.com/IJCIET/index.asp
%
weight
loss
Corrosion
rate
mm\yr
2.5
2.7
13.624
15.530
12.099
0.2
1.302
12.411
12.396
0.12
0.697
7.43
11.765
11.758
0.06
0.325
7.28
12.724
12.719
0.03
0.232
Figure 2
612
editor@iaeme.com
Experimental Investigation of Anticorrosive Rebar Coating Over Mildsteel Rod Using Plastic Wastes
Figure 3
Figure 4
Figure 1, Figure 2, Figure 3 shows the result of weight loss test in acid, basic and in NaCl
medium respectively. The dissociation rate of untreated MS sample lower than treated sample
in acid medium but the results are vice versa in other two mediums which can be concludes
that the treated samples can be effectively used against corrosion in concrete which is basic in
nature (pH : 11- 12.5) and also for off shore works. Figure 4 shows that results of pH before
and after immersion. Irrespective of mediums for both treated and untreated samples, pH
values get reduced after immersion due to acid based reactions.
3.2. Electrochemical Impedance Spectroscopy
Three-electrode setup:
Working Electrode
Reference Electrode
Counter Electrode
Electrolyte
-
MS Sample
Glass Electrode
Platinum Electrode
3.5% NaCl Solution
Table 3 Results of EIS experiment
System
Temp
(ºC)
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
600
400
700
400
600
Where
Icorr
Rs
Rct
CDL
-
Ratio
Steel :
PET
1:1
1:1
1:1
1:0.5
1:0.5
Corrosion rate
Icorr
(mA/cm2)
mm/yr
mpy
0.18008
11.574
0.0813
13.52
0.37942
2.095
134.1
0.9472
153.2
4.395
0.053
3.406
0.0241
3.891
0.112
Rs
(ohm
scm2)
19.45
6.858
53.65
8.256
42.37
RCT
(Ohm
scm2)
144.3
2.255
319.2
3.113
68.8
corrosion current.
resistance of the medium.
resistance of the MS sample.
capacitance of double layer.
http://www.iaeme.com/IJCIET/index.asp
613
editor@iaeme.com
mm/yr
J. Jeyanthi
Series1
sample1
2.0950
sample3
0.9472
sample5
4.3950
mA/cm2
Figure 5 Corrosion Rate
Series1
sample1
0.1801
sample3
0.0813
sample5
0.3794
Figure 6 Corrosion Current [ ICorr]
Figure 7 RS vs RCT
According to EIS if a sample has to be a corrosion resistant, the value of Rct should be
higher than that of Rs. Thus from Table 3, it is clearly observed that sample 2 and sample 4
gets corroded more in the NaCl medium as their Rct< Rs. Whereas all other samples have their
Rct> Rs thereby getting a corrosion resistant property.
http://www.iaeme.com/IJCIET/index.asp
614
editor@iaeme.com
Experimental Investigation of Anticorrosive Rebar Coating Over Mildsteel Rod Using Plastic Wastes
Among samples 1, 3 and 5, sample 3 is more corrosion resistant as its corrosion rate
comparatively lower which is clearly shown in Figure 5. Similarly the value of corrosion
current is also lesser for sample 3 which is clearly shown in Figure 6.
As a result of the EIS experiment as shown in table 3, it is concluded that optimum
temperature to induce a corrosion resistant property to the rebar is 700°C and optimum weight
ratio of rebar and PET is 1:1.
3.3. SEM ANALYSIS
The scanning electron microscope gives the morphological structure by an image. It takes the
image of a sample by scanning it with a high energy beam of electrons in a raster scan pattern.
Here the morphology of the treated surfaces are analyzed using HITACHI SUI510 scanning
electron microscope operating at 10KV.
Figure 8 SEM image of coated mildsteel rod.
The above figure 5 shows the SEM image of treated MS sample in cross section, it shows
the coating thickness of PET over MS rod varies from 1.19 micron – 3.37 micron.
4.CONCLUSIONS

From weight loss method, it was concluded that the treated samples can be effectively used
against corrosion in concrete which is basic in nature (pH: 11- 12.5) and also for off shore
works.

From EIS experiment, it was found that optimum temperature to induce a corrosion resistant
property to the rebar is 700 ºC and optimum weight ratio of rebar and PET is 1:1.

The SEM image of treated MS sample shows the coating thickness varies from 1.19 micron –
3.37 micron.

The optimum temperature for treating rebar is 700 ºC, however the minimum treating
temperature is 600 ºC.
REFERENCES
[1]
Behzadnasab, M., S. M. Mirabedini, and M. Esfandeh. "Corrosion protection of steel by
epoxy nanocomposite coatings containing various combinations of clay and
nanoparticulate zirconia." Corrosion Science 75 ,2013, pp,134-141.
http://www.iaeme.com/IJCIET/index.asp
615
editor@iaeme.com
J. Jeyanthi
[2]
Chavan, Naveen Manhar, B. Kiran, A. Jyothirmayi, P. Sudharshan Phani, and G.
Sundararajan. "The corrosion behavior of cold sprayed zinc coatings on mild steel
substrate." Journal of thermal spray technology 22, no. 4, 2013,pp, 463-470.
[3]
Esfahani, Erfan Abedi, Hamidreza Salimijazi, Mohamad A. Golozar, Javad Mostaghimi,
and Larry Pershin. "Study of corrosion behavior of arc sprayed aluminum coating on mild
steel." Journal of thermal spray Technology 21, no. 6, 2012,pp,1195-1202.
[4]
Ohtsuka, Toshiaki. "Corrosion protection of steels by conducting polymer coating."
International Journal of Corrosion ,2012
[5]
Poursaee, Amir. "Corrosion of steel in concrete structures." In Corrosion of Steel in
Concrete Structures, pp, 19-33. Woodhead Publishing, 2016.
[6]
Shi, Weizhou, Lewei Tong, Yiyi Chen, Zigang Li, and Kai Shen. "Experimental study on
influence of corrosion on behavior of steel material and steel beams." Jianzhu Jiegou
Xuebao(Journal of Building Structures) 33, no. 7, 2012,pp, 53-60.
[7]
Tang, Fujian, Genda Chen, Jeffery S. Volz, Richard K. Brow, and Mike Koenigstein.
"Microstructure and corrosion resistance of enamel coatings applied to smooth reinforcing
steel." Construction and Building Materials 35, 2012, pp, 376-384.
[8]
Umoren, S. A., I. B. Obot, A. U. Israel, P. O. Asuquo, M. M. Solomon, U. M. Eduok, and
A. P. Udoh. "Inhibition of mild steel corrosion in acidic medium using coconut coir dust
extracted from water and methanol as solvents." Journal of Industrial and Engineering
Chemistry 20, no. 5, 2014, pp, 3612-3622.
[9]
Ye, Chen-Qing, Rong-Gang Hu, Shi-Gang Dong, Xiao-Juan Zhang, Rui-Qing Hou, RongGui Du, Chang-Jian Lin, and Jin-Shan Pan. "EIS analysis on chloride-induced corrosion
behavior of reinforcement steel in simulated carbonated concrete pore solutions." Journal
of Electroanalytical Chemistry 688, 2013, pp,275-281.
[10]
Zavareh, Mitra Akhtari, Ahmed Aly Diaa Mohammed Sarhan, Bushroa Binti Abd Razak,
and Wan Jeffrey Basirun. "Plasma thermal spray of ceramic oxide coating on carbon steel
with enhanced wear and corrosion resistance for oil and gas applications." Ceramics
International 40, no. 9, 2014, pp, 14267-14277.
http://www.iaeme.com/IJCIET/index.asp
616
editor@iaeme.com