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GSJ: Volume 7, Issue 9, September 2019, Online: ISSN 2320-9186
www.globalscientificjournal.com
BEHAVIORAL FAILURE LOAD AND MIDSPAN DEFLECTION OF
REINFORCED CONCRETE BEAMS OF CORRODED AND COATED
MEMBERS Charles Kennedy1, Damini Righteous Gilbert
2, Toscanini Dein Seimodei3
3Faculty of Engineering, Department of Civil Engineering, Rivers State University,
Nkpolu, Port Harcourt, Nigeria 2Faculty of Engineering, Department of Civil Engineering, Federal University,
Otuoke, Bayelsa State, Nigeria 3Faculty of Engineering, Department of Civil Engineering, Niger Delta University,
Wilberforce Island, Bayelsa State
Authors E-mail: 1ken_charl@yahoo.co.uk,
1pythagoras4maths@yahoo.com 31toscanini1468@yahoo.com
ABSTRACT
Load-carrying capacity, stiffness and force redistribution of reinforced concrete structure is affected by the corrosion of
reinforcement embedded into concrete. This study investigated the comparative effect of coated reinforcing steel with
khaya senegalensis exudates / resins and that of corroded residual flexural strength after 150 days corrosion accelerated
periods. Flexural failure load of corroded has percentile variation of -35.3841% against 54.7607% and 52.5252% non-
corroded and exudates coated specimens. Midspan deflection with percentile variation of 89.11864% against -47.1231%
and -42.1841% non-corroded and coated specimens. Average ultimate tensile strength with percentile difference of -
12.193% against 13.88614% and 13.64808% of non-corroded and coated specimens. Average strain ratios with
percentile variation of-10.1738% against 11.3261% and -11.16659% of non-corroded and coated specimens. Averaged
elongations with percentile variation of -40.0134% against 66.7038% and 61.44629% for non-corroded and coated
specimens. Corroded members entire results showed high; flexural failure loads against non-corroded and coated
specimens, midspan deflection against non-corroded and coated specimens and ultimate tensile strength of corroded
specimens against non-corrode and coated specimens. Corrosion attacked on the mechanical properties of reinforcing
steel embedded in concrete led to the behavioral states of tested properties.
Key Words: Corrosion, Corrosion inhibitors, Flexural Strength, Concrete and Steel Reinforcement
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1.0 Introduction
The corrosion of steel reinforcement embedded in concrete structures often result to the breakdown of the
passive film formed due to highly alkaline environment around reinforcing steel. The end results of steel corrosion
are manifested as a reduction in the bar diameter, wear and tear of the mechanical properties of the reinforcing
steel. Reinforced concrete structures built within the marine environment are at risk due to chloride-induced
corrosion of reinforcement which resulted from the presence of high chloride concentrations and humid or
saturated conditions. Rebar corrosion is generally accompanied by the loss of rebar cross section and accumulation
of corrosion products, which occupy much larger volume than the original steel (Broomfield[1]). The formation of
surface films covering the metal, while generally protective, can give rise to localized corrosion attack and
pitting (Scully [2]). (Bertolini et al. [3], Lounis et al. [4], Elsener [5]), concluded that there is instantaneous film
formation in steel in an oxidizing atmosphere such as air, and once the formation of layer is noticed, metal is
"passivated" and the oxidation or "rusting" rate will slow down to less than 0.04 mills per year (mpy).
Charles et al. [6] investigated the residual yield strength structural capacity effect of non-corroded, corroded and
inhibited steel bar. The results of coated steel bar with three different resins / exudates extracts of Symphonia
globulifera linn, ficus glumosa and acardium occidentale l.) versus corroded on comparison, the flexural strength
failure load are 29.50%, 28.505,29.57% against 22.30% corroded, midspan deflection are 31.14%,25.30%, 22.30%
against 39,30% corroded, tensile strength 11.84%, 12.13%, 12.14% against 10.17% and elongation are 32.40%,
32.13%, 32.40% against 46.30% corroded. Overall results indicated that coated steel bar showed higher values
increased in failure load and tensile strength while corroded decreased in elongation and midspan deflection.
Charles et al. [7] investigated the effect on flexural residual yield strength capacity of three different
resins/exudates extract of trees of dacryodes edulis, moringa oleifera lam, mangifera indica paste coated
reinforcement on the concrete beam. Flexural strength failure loads of coated members with dacryodes edulis,
moringa oleifera lam, mangifera indica are 35.78%, 27.09%, 29.42% against 22.30% decreased in corroded,
midspan deflection are 18.57%, 28.30%, 27.43% against 39.30% increased in corroded, elongation are 28.75%,
31.50%, 31.60 against 46.30% increased in corroded and tensile strength are 14.18%, 12.29%, 12.08% as against
10.17% decreased in corroded respectively. Entire results showed that low load subjection is recorded in coated
members at failure loads as against in corroded with high deflection and elongation. This high yield was attributed
to corrosion attack.
Charles et al. [8] examined the effect/impact of corrosion inhibitors on flexural strength of failure load, midspan
deflection, tensile strength and elongation of steel reinforcement layered with resins/exudates of magnifera indica
extracts as corrosion inhibitors. Results recorded on experimental work showed flexural strength failure load,
midspan deflection, tensile strength and elongation as 29.09%,31.20%, 11.75% and 31.50% for non-corroded,
29.42%, 27.43%, 12.09% and 31.60% for coated concrete beam respectively. For corroded concrete beam
members, failure load decreased to 22.505, midspan deflection increased by 39.30%, tensile strength decreased to
10.17% while elongation increased by 46.30%. Entire results showed the effect of corrosion on the flexural
strength of reinforcement that led to low load on failure load and higher midspan deflection on corroded beams
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and hiher load on failure load and low midspan deflection on non-corroded and coated concrete beam members
resulting to attack on surface condition of reinforcement from corrosion.
Charles et al. [9] investigative study was carried out to ascertain the utilization of natural inorganic extracts of tree
resin/exudates to assess the yield strength capacity of reinforced concrete beam members under corrosion
accelerated medium. Results obtained showed presence of corrosion on uncoated concrete beam members with
the presence of pitting and cracks. Non – corroded and coated members in comparison with corroded recorded
increasing values on flexural strength failure load by 23.8% and 29.59% against 22.30% of corroded, tensile
strength non – corroded and coated increased by 12.03%, 12.14% over 10.17 % of corroded while decreasing
values on midspan deflection of 28.30% and 22.30%, elongation 31.5% and 32.46% recorded on non-corroded and
coated concrete beam members as against 39.30% and 46.30% of corroded respectively. Overall results indicated
lower failure loads on corroded and tensile strength on corroded members, higher load on midspan and
elongation, resulted from an attack and degradation on the yield strength capacity due to corrosion potentials.
Charles et al. [10] investigated the effects of corrosion on the residual structural steel bar capacity of
resins/exudates inhibited and non-inhibited reinforced concrete beam members. Results recorded results on non-
corroded flexural strength test of failure load 29.09%, midspan deflection 28.30%, tensile strength 12.03% and
elongation 31.50%, for coated beam members, failure load 29.42%, midspan deflection 27.42%, tensile strength
12.09% and elongation 31.80%, for corroded beam members, failure load decreased by 22.50%, midspan
deflection increased by 39.30%, tensile strength decreased to 10.17% and elongation by increased 46.30%. The
entire experimental results showed that corroded specimens has lower flexural load, higher midspan deflection,
lower tensile strength and higher elongation due to loss of steel bar fibre from degradation effect from corrosion,
inhibitors served as protective coating against corrosion, but no strength was added to steel members.
Otunyo and Kennedy [11] investigated the effect of corrosion on the flexural strength and mid-span deflection of
steel reinforcements coated with resins / exudates of trees extract known as inorganic inhibitors (dacryodes
edulis-African Pear). Results obtained indicated that the flexural failure strength, and elongation increased by
(29%) and (48%) respectively for the dacryodes edulis coated steel members, the mid-span deflection decreased
by 26%, elongation increased by 23% and 32% respectively, while the mid-span deflection decreased by 40%.. The
resin (mdacryodes edulis) added strength to the reinforcement.
Charles et al. [12] experimented on the effects of corrosion and inhibitors (Inorganic origin) extracts known as
resins/exudates from trees barks on the residual flexural strength of concrete beam members immersed in
corrosion accelerated medium for 90 days to ascertain possible changes on surface conditions of investigated
samples. Results obtained of corroded concrete beam members were 22,50%, 39.30%, 10.19% and 46.30 of failure
load, midspan deflection, ultimate tensile strength and elongation, for non- 29.09%, 28.30%, 12.03% and 31.50%,
for coated beam members , 28.5%, 25.30%, 12.13% and 32.12% respectively. These results indicated increased in
flexural failure load and ultimate tensile strength and decreased in midspan deflection and elongation respectively
in corroded concrete beam members. This showed lower load and higher deflection in corroded members and
higher in non-corroded and coated, higher elongation in corroded and lower in non-corroded and coated.
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Charles et al. [13] performed and investigated on uncoated and corrosion inhibitors (Symphonia globulifera linn)
resins / exudates paste coated steel reforcing bar. Results obtained on comparison between uncoated (corroded)
and coated are flexural failure load 22.50% to 29.50%, midspan deflection 39.30% to 31.14%, tensile strength
10.17% to 11.84% and elongation 46.30% to 32.40% respectively. Thus, results showed decreased in failure load
and tensile strength of corroded members while increased in midspan deflection and elongation. This attributes
was due to effect of corrosion and reduction in strength from degradation properties. Resins / exudates coated
members showed higher failure load with low deflection.
2.0 MATERIALS AND METHODS FOR EXPERINMENT
2.1 Aggregates
The fine aggregate and coarse aggregate were purchased. Both met the requirements of [14].
2.1.2 Cement
Portland limestone cement grade 42.5 is the most and commonly type of cement in Nigerian Market. It was used
for all concrete mixes in this investigation. The cement met the requirements of [15].
2.1.3 Water
The water samples were clean and free from impurities. The fresh water used was gotten from the tap at the Civil
Engineering Department Laboratory, Kenule Beeson Polytechnic, Bori, and Rivers State. The water met the
requirements of [16]
2.1.4 Structural Steel Reinforcement
The reinforcements are gotten directly from the market in Port Harcourt [17]
2.1.5 Corrosion Inhibitors (Exudates/ Resins ) Khaya senegalensis
The study inhibitor (Khaya senegalensis Exudates) of natural tree resins/exudates extracts.
2.2 METHODS
Present study involves direct application of resins / exudates of trees extract known as inorganic inhibitor khaya
senegalensis exudates, layered/coated on reinforcement steel ribbed surface. The objective of this study was to
determine the usefulness of locally available surface-applied corrosion inhibitors under severe corrosive
environments and with chloride contamination. The test setup simulates a harsh marine environment of saline
concentration. The samples of reinforced concrete beams of 150 mm x 150 mm × 650 mm, thickness, width and
length specimens and ribbed bars of 16 mm embedded for corrosion test and flexural test for beam was
investigated. This was aimed at achieving the real harsh and corrosive state, concrete specimens were ponded in
solutions (NaCl) and the depth of the solution was maintained for the given period of experiment as to observe the
significant changes that resulted from the actions of the accelerator (NaCl) and the specimens. The determination
of the contribution of the resins will be observed through its adhesive ability with the reinforcement through
surface coating application and the bonding relationship between the coated specimens and concrete, its
waterproofing and resistive nature (resistance) against accelerator penetration into the bare reinforcement.
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2.2.1 Specimen Preparation and Casting of Concrete Beams
Standard method of concrete mix ratio was adopted, batching by weighing materials manually. Concrete mix ratio
of 1:2:4 by weight of concrete, water-cement ratio of 0.65. Manual mixing was used on a clean concrete banker,
and mixture was monitored and water added gradually to obtain perfect mix design concrete. Standard
uniform color and consistency concrete was obtained by additions of cement, water and aggregates. The test
beams were cast in steel mould of 150mm x 150 mm x 750 mm. Fresh concrete mix for each batch was fully
compacted by tamping rods, to remove trapped air, which can reduce the strength of the concrete and 16 mm
reinforcements of coated and non-coated were spaced at 150 mm with concrete cover of 25 mm had been
embedded inside the beam and projection of 100 mm for half-cell potential measurement. Specimens were molds
are removed from specimen after 24hrs and cured for 28 days. The specimens were cured at room temperature in
the curing tanks for accelerated corrosion test process and testing procedure allowed for 120 days first crack
noticed and a further 30 days making a total of 150 days for further observations on corrosion acceleration
process.
2.2.2 Flexure testing of Beam Specimens
Universal Testing Machine in accordance with BS EN 12390-2 was used for the flexural test and a total of 27 beam
specimens were tested. After curing for 28 days, 6 controlled beams (non-corroded) was kept in a control state,
preventing corrosion of reinforcement, while 18 beam samples of non-coated and exudates /resins coated were
partially place in ponding tank for 150 days and examined accelerated corrosion process. After 150 days, the
accelerated corrosion subjected samples were examined to determine residual flexural strength. Beam specimens
were simply supported on a span of 650mm. An Instron Universal Testing Machine of 100KN capacity at a slow
loading rate of 1 mm/min was used in the flexural test. Beam samples were placed in the machine to specification,
flexural test were conducted on a third point at two supports. Load was applied to failure with cracks noticed and
corresponding values recorded digitally in a computerized system.
2.2.3 Tensile Strength of Reinforcing Bars
To ascertain the yield and tensile strength of tension bars, bar specimens of 16 mm diameter of non-corroded,
corroded and coated were tested in tension in a Universal Testing Machine and subjected to direct tension until
failure; the yield, maximum and failure loads being recorded. To ensure consistency, the remaining cut pieces from
the standard length of corroded and non-corroded steel bars were subsequently used in the bond and flexural
test.
3.0 RESULTS AND DISCUSSIONS
Results of 27 samples in table 3.1, 3.2 and 3.3 are derived into averaged values in 3.4 and summarized into
summary of averages, percentile values and percentile values difference in 3.5of flexural strength of concrete
beam members as sampled, arbitrarily cast, cured for 28 days on normal and standard method, accelerated in
corrosion medium environment for 120days at first cracks observation and 30days extended period and graphically
represented in figures 3.1 - 3.3A.
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3.1 Non-corroded Concrete Beam Members
Flexural failure load of non-corroded samples average values from table 3.1 into 3.4 and 3.5 are 80.87kN,
80.756kN, 81.226kN, computed into 80.95111kN with percentile variation of 54.7607% to -35.3841% corroded
specimens. Average values of 6.5733mm, 6.816mm, 6.2766mm, computed into 6.555556mm with percentile
variation of -47.1231% against 89.11864% corroded specimens of midspan deflection. Yield strength values are
460MPa, computed into 100% with 0.00% percentile variation. Ultimate tensile strength values are 631.213MPa,
630.946MPa, and 630.646MPa, computed into 630.9356MPa with percentile variation of 13.88614% against -
12.193% corroded specimens. Average strain ratios are 1.311, 1.315, and 1.305, computed to 1.310556 with
percentile variation values of 11.3261% against -10.1738%. Averaged elongations are 27.485%, 27.208%,
27.6083%, summed up to 27.43389% with percentile variation 66.7038% over -40.0134%. Non-corroded members
do not changed in any form mechanical properties of reinforcing steel. All laboratory tests were all with standard.
3.2 Corroded Concrete Beam members
Flexural failure load of corroded samples average values from table 3.2 into 3.4 and 3.5 are 52.982KN, 51.929kN,
52.009kN, computed into 52.30728kN with percentile variation of -35.3841% against 54.7607% and 52.5252% non-
corroded and khaya senegalensis exudates coated specimens. Midspan deflection average values are 12.613mm,
12.313mm, 12.266mm, computed into 12.39778mm with percentile variation of 89.11864% against -47.1231% and
-42.1841% non-corroded and coated specimens. Average yield strength values are 460MPa, computed into 100%
with 0.00% of percentile values. Average ultimate tensile strength values are 554.983MPa, 553.45MPa,
553.583MPa, computed into 554.0056MPa, with percentile difference of -12.193% against 13.88614% and
13.64808% of non-corroded and coated specimens. Average strain ratios are 1.1783, 1.185, and 1.1683, computed
into 1.177222 with percentile variation of-10.1738% against 11.3261% and -11.16659% of non-corroded and
coated specimens. Averaged elongations are 16.543%, 16.323%, 16.503%, computed into 16.45667% with
percentile variation of -40.0134% against 66.7038% and 61.44629% for non-corroded and coated specimens.
Corroded members entire results showed high; flexural failure loads against non-corroded and coated specimens,
midspan deflection against non-corroded and coated specimens, and ultimate tensile strength of corroded
specimens against non-corrode and coated specimens. Corrosion attacked on the mechanical properties of
reinforcing steel embedded in concrete led to the behavioral states of tested properties.
3.3 Khaya senegalensis Resins/Exudates Steel Coated Concrete Beam Members.
Flexural failure load of coated samples averaged values from table 3.3 into 3.4 and 3.5 are 79.720kN, 79.827kN,
79.797kN, computed into 79.78178kN with percentile variation of 52.5252% over -35.3841% over corroded
specimens. Midspan deflection averaged values are 7.135mm, 7.1923mm, 7.175mm, computed into 7.167889mm
with percentile variation -42.1841% over 89.11864% corroded specimens. Averaged yield strength is 460MPa,
computed into 100% with 0.00% with percentile value. Average ultimate tensile strength values are 629.616MPa,
629.65MPa, 629.583MPa, computed into 629.6167MPa, with percentile variation of 13.64808% against -12.193%
corroded specimens. Averaged strain ratios are 1.317, 1.3009, and 1.307, computed into 1.308678 with percentile
variation of 11.16659% against -10.1738% of corroded specimens. Averaged elongations are 26.550%, 26.607%,
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26.547%, computed into 26.56868% with percentile variation of 61.44629% against -40.0134% of corroded
specimens. Coated members from the experimental work showed low; flexural failure load, midspan deflection,
strain ratio and ultimate tensile strength. Entire results the potential utilization of Khaya senegalensis exudates /
resins in corrosion protection against reinforcing steel in concrete.
Table 3.1: Flexural Strength of Beam Specimens (Non-Corroded specimens)
s/no Non-corroded Control Beam
Beam Samples VAG VBG VCG VDG VEG VFG VGG VHG VIG
ZBJ1-1 Failure Load (KN)
80.93 80.93 80.75 80.72 80.72 80.83 81.53 80.5 81.65
ZBJ1-2 Midspan Deflection
(mm)
6.32 6.4 7 7.11 6.2 7.14 6.23 6.4 6.2
ZBJ1-3 Bar diameter
(mm)
16 16 16 16 16 16 16 16 16
ZBJ1-4 Yield Strength, fy (MPa)
460 460 460 460 460 460 460 460 460
ZBJ1-5 Ultimate Tensile
Strength, fu (MPa)
630.38 632.28 630.98 629.78 632.28 630.78 630.58 631.38 629.98
ZBJ1-6 Strain Ratio
1.335 1.295 1.305 1.335 1.305 1.305 1.305 1.295 1.315
ZBJ1-7 Elongation (%)
27.385 27.585 27.485 27.555 26.985 27.085 27.585 27.555 27.685
Table 3.2 : Flexural Strength of Beam Specimen (Corroded specimens) s/no Corroded Beam
Beam Samples VAG1 VBG1 VCG1 VDG1 VEG1 VFG1 VGG1 VHG1 VIG1
ZBJ2-1 Failure load (KN)
53.3395 54.0195 51.5895 51.0695 53.3595 51.3595 51.1295 53.5595 51.3395
ZBJ2-2 Midspan deflection
(mm)
12.85 12.68 12.31 12.28 11.88 12.78 12.31 11.91 12.58
ZBJ2-3 Bar diameter
(mm)
16 16 16 16 16 16 16 16 16
ZBJ2-4 Yield Strength, fy (MPa)
460 460 460 460 460 460 460 460 460
ZBJ2-5 Ultimate Tensile
Strength, fu (MPa)
557.05 553.65 554.25 553.55 553.25 553.55 552.95 554.25 553.55
ZBJ2-6 Strain Ratio
1.185 1.175 1.175 1.215 1.165 1.175 1.175 1.165 1.165
ZBJ2-7 Elongation (%)
16.56 16.7 16.37 15.9 16.89 16.18 16.7 16.4 16.41
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Table 3.3: Flexural Strength of Beam Specimens (Exudates/Resins Coated specimens)
Khaya senegalensis exudates ( steel bar coated specimen)
s/no 150µm (Exudate/Resin) coated 300µm (Exudate/Resin) coated 450µm (Exudate/Resin) coated
Beam Samples VAG2 VBG2 VCG2 VDG2 VEG2 VFG2 VGG2 VHG2 VIG2
ZBJ3-1 Failure load (KN)
79.304 80.254 79.604 79.644 80.004 79.834 79.604 79.644 80.144
ZBJ3-2 Midspan Deflection
(mm)
7.239 6.639 7.529 7.339 6.899 7.339 7.319 7.319 6.889
ZBJ3-3 Bar diameter (mm)
16 16 16 16 16 16 16 16 16
ZBJ3-4 Yield Strength, fy
(MPa)
460 460 460 460 460 460 460 460 460
ZBJE-5 Ultimate Tensile
Strength, fu (MPa)
629.15 630.05 629.65 629.65 629.65 629.65 629.25 629.75 629.75
ZBJ3-6 Strain Ratio 1.3109 1.3309 1.3109 1.3009 1.3009 1.3009 1.2909 1.3109 1.3209
ZBJ3-7 Elongation (%)
26.3109 26.9309 26.4109 26.3809 26.8309 26.6109 26.5209 26.2309 26.8909
Table 3.4: Average Flexural Strength of Beam Specimens (Non-Corroded, Corroded Exudates/Resins Coated Specimens)
s/no Samples Non-Corroded Specimens Average Values
Corroded Specimens Average Values
Coated Specimens Average Values
ZBJ4-1
Failure load (KN)
80.87 80.756 81.226 52.982 51.929 52.009 79.720 79.827 79.797
ZBJ4-2
Midspan Deflection
(mm)
6.5733 6.816 6.2766 12.613 12.313 12.266 7.135 7.1923 7.175
ZBJ4-3
Bar diameter (mm)
16 16 16 16 16 16 16 16 16
ZBJ4-4
Yield Strength, fy (MPa)
460 460 460 460 460 460 460 460 460
ZBJ4-5
Utimate Tensile Strength, fu
(MPa)
631.213 630.946 630.646 554.983 553.45 553.583 629.616 629.65 629.583
ZBJ4-6
Strain Ratio 1.311 1.315 1.305 1.1783 1.185 1.1683 1.317 1.3009 1.307
ZBJ4-7
Elongation (%) 27.485 27.208 27.6083 16.543 16.323 16.503 26.550 26.607 26.547
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Table 3.5: Summary of Percentile Flexural Strength of Beam Specimens (Non-Corroded, Corroded, Exudates/Resins Coated Specimens)
Beam Samples Summary of Averages Percentile Values Percentile Difference
ZBJ5-1 Failure load (KN)
80.95111 52.30728 79.78178 154.7607 64.61589 152.5252 54.7607 -35.3841 52.5252
ZBJ5-2 Midspan Deflection
(mm)
6.555556 12.39778 7.167889 52.87686 189.1186 57.81592 -47.1231 89.11864 -42.1841
ZBJ5-3 Bar diameter
(mm)
16 16 16 100 100 100 0 0 0
ZBJ5-4 Yield Strength, fy (MPa)
460 460 460 100 100 100 0 0 0
ZBJ5-5 Ultimate Tensile
Strength, fu (MPa)
630.9356 554.0056 629.6167 113.8861 87.807 113.6481 13.88614 -12.193 13.64808
ZBJ5-6 Strain Ratio
1.310556 1.177222 1.308678 111.3261 89.8262 111.1666 11.3261 -10.1738 11.16659
ZBJ5-7 Strain (%) 27.43389 16.45667 26.56868 166.7038 59.98663 161.4463 66.7038 -40.0134 61.44629
Figure 3.1: Failure Load versus Midspan Deflection of Beam Specimens (Non-Corroded,
Corrode and Resin Coated Specimens)
0
20
40
60
80
100
6.2
6.2
3
6.4
6.6
39
6.8
99
7.1
1
7.2
39
7.3
19
7.3
39
11
.88
12
.28
12
.31
12
.68
12
.85
Failu
re lo
ad (
KN
)
Midspan Deflection (mm)
Non-Corroded ControlConcrete BeamSpecimens
Corroded ConcreteBeam Specimens
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Figure 3.1A: Average Failure Load versus Midspan Deflection of Beam Specimens (Non-Corroded,
Corrode and Resin Coated Specimens)
Figure 3.2: Ultimate Tensile Strength versus Yield Strength of Beam Specimens
(Non-Corroded, Corrode and Resin Coated Specimens)
Figure 3.2A: Average Ultimate Tensile Strength versus Yield Strength of Beam Specimens
(Non-Corroded, Corrode and Resin Coated Specimens)
0
20
40
60
80
100
Failu
re lo
ad (
KN
)
Midspan Deflection (mm)
Non-Corroded ControlConcrete Beam Specimens
Corroded Concrete BeamSpecimens
Khaya senegalensisExudates ( steel bar coatedspecimen) 150µm, 300µm,450µm)
500
520
540
560
580
600
620
640
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0
46
0Ult
imat
e T
en
sile
Str
en
gth
, fu
(M
Pa)
Yield Strength, fy (MPa)
Non-Corroded ControlConcrete Beam Specimens
Corroded Concrete BeamSpecimens
Khaya senegalensisExudates ( steel barcoated specimen) 150µm,300µm, 450µm)
500
520
540
560
580
600
620
640
460 460 460 460 460 460 460 460 460Ult
imat
e T
en
sile
Str
en
gth
, fu
(M
Pa)
Yield Strength, fy (MPa)
Non-Corroded ControlConcrete Beam Specimens
Corroded Concrete BeamSpecimens
Khaya senegalensisExudates ( steel barcoated specimen) 150µm,300µm, 450µm)
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Figure 3.3: Ultimate Tensile Strength versus Strain Ratio of Beam Specimens
(Non-Corroded, Corrode and Resin Coated Specimens)
Figure 3.3A: Average Ultimate Tensile Strength versus Strain Ratio of Beam Specimens
(Non-Corroded, Corrode and Resin Coated Specimens)
500
520
540
560
580
600
620
640
1.1
65
1.1
65
1.1
75
1.1
75
1.2
15
1.2
95
1.3
00
9
1.3
00
9
1.3
05
1.3
05
1.3
10
9
1.3
15
1.3
30
9
1.3
35
Ult
imat
e T
en
sile
Str
en
gth
, fu
(M
Pa)
Strain Ratio
Non-Corroded ControlConcrete Beam Specimens
Corroded Concrete BeamSpecimens
Khaya senegalensisExudates ( steel barcoated specimen) 150µm,300µm, 450µm)
500
520
540
560
580
600
620
640
Ult
imat
e T
en
sile
Str
en
gth
, fu
(M
Pa)
Strain Ratio
Non-Corroded ControlConcrete BeamSpecimens
Corroded ConcreteBeam Specimens
500520540560580600620640
15
.9
16
.37
16
.41
16
.7
16
.89
26
.31
09
26
.41
09
26
.61
09
26
.89
09
26
.98
5
27
.38
5
27
.55
5
27
.58
5
27
.68
5
Ult
imat
e T
en
sile
Str
en
gth
, fu
(M
Pa)
Elongation (%)
Non-Corroded ControlConcrete Beam Specimens
Corroded Concrete BeamSpecimens
Khaya senegalensisExudates ( steel barcoated specimen) 150µm,300µm, 450µm)
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Figure 3.4: Ultimate Tensile Strength versus Elongation of Beam Specimens
(Non-Corroded, Corrode and Resin Coated Specimens)
Figure 3.4A: Average Ultimate Tensile Strength versus Elongation of Beam Specimens
(Non-Corroded, Corrode and Resin Coated Specimens)
4.0 CONCLUSIONS
Experimental results gotten from tables 3.1 – 3.5 and figures 3.1 – 3.3A, the below conclusions were drawn:
i. Non-corroded members do not changed in any form mechanical properties of reinforcing steel. All
laboratory tests were all with standard.
ii. Corroded members entire results showed high; flexural failure loads against non-corroded and coated
specimens, midspan deflection against non-corroded and coated specimens, ultimate tensile strength of
corroded specimens against non-corrode and coated specimens.
iii. Corrosion attacked on the mechanical properties of reinforcing steel embedded in concrete led to the
behavioral states of tested properties.
iv. Coated members from the experimental work showed low; flexural failure load, midspan deflection,
strain ratio and ultimate tensile strength.
500520540560580600620640
Ult
imat
e T
en
sile
Str
en
gth
, fu
(M
Pa)
Elongation (%)
Non-Corroded ControlConcrete Beam Specimens
Corroded Concrete BeamSpecimens
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REFERENCES
[1] J.G. Broomfield, “Corrosion of steel in concrete: understanding, repair and investigation, First Edition, E and FN Spon, UK, 1997. . [2] J.C. Scully, “The fundamentals of corrosion, International Series on Material Science and Technology,” Second Edition, UK., 1975.
[3] L. Bertolini, B. Elsener, P. Pedeferri and R.Polder,” Corrosion of steel in concrete prevention, diagnosis, repair, Wiley-VCH,” Weinheim 2004.
[4] Z. Lounis, J. Zhang and L. Daigle,” Probabilistic study chloride-induced corrosion of carbon steel in concrete structures, 9th ASCE Joint Specialty Conference on Probablistic Mechanisms and Structural Reliability,” Albuquerque, New Mexico, pp. 1-6, 2004. *5+ B. Elsener,” Corrosion rate of steel in concrete measurements beyond the Tafel Low,” Corrosion Science, no.47, pp.3019-3033, 2005.
[6] K. Charles, O. Ishmael,B. M. Akatah, P. P. Akpan., ”Comparative Residual Yield Strength Structural Capacity of Non-corroded, Corroded and Inhibited Reinforcement Embedded in Reinforced Concrete Structure and Exposed to severely Medium”. International Journal of Scientific and Engineering Research, vol. 9, no. 4, pp.1135-1149, 2018. [7] K. Charles, T. T. W. Terence, O. Kelechi, I. S. Okabi, I,” Investigation on Comparative Flexural Residual Yield Strength Capacity of Uncoated and Coated Reinforcement Embedded in Concrete and Exposed to Corrosive Medium,” International Journal of Scientific & Engineering Research, vol. 9, no. 4,pp.655-670, 2018. [8] K. Charles, S. K. Gbinu, K. Ugo, ”Load Carrying Capacity Of Coated Reinforcement With Exudates Of Concrete Beam In Corrosion Solution Ponding,” International Journal of Civil and Structural Engineering Research, vol. 6, no.1, pp: 5-12, 2018 [9] K. Charles, E. I. Ogunjiofor, L. P. Latam,” Yield Strength Capacity of Corrosion Inhibited (Resins / Exudates) Coated Reinforcement Embedded in Reinforced Concrete Beam and Accelerated in Corrosive Medium,” European International Journal of Science and Technology, vol. 7, no. 3, pp.25-33, 2018. [10] Charles, K., Akpan, P, P., and Gbinu, S, K.,” Corrosion Effects on Residual Structural Capacity of Resins / Exudates Inhibited Steel Reinforcement Flexural Beam,” European Journal of Engineering Research and Science, vol.3, no. 5, pp. 31-35, 2018. [11] A. W. Otunyo and K. Charles, K, ”Effect Of Corrosion On Flexural Residual Strength And Mid-Span Deflection Of Steel (Coated With Resins/Exudates of Trees) Reinforced Concrete Beams Under Sodium Chloride Medium,” European International Journal of Science and Technology, vol. 6 no. 7, pp.77-87, 2017. [12] K. Charles, E. I. Ogunjiofor, L. P. Letam, ” Residual Flexural Strength of Corrosion Inhibited Resin Coated Beam in Corrosion Accelerated Media”, Global Scientific Journal, vol. 6, no. 5, pp. 84-96, 2018. [13] K. Charles, L. P. Letam, S. K. Gbinu, S,” Effect of Resins / Exudates Inhibited Steel on the Flexural strength of Reinforced Concrete Beam under Corrosive Environment,” International Journal of Advances in Scientific Research and Engineering, vol. 4, no. 4, pp. 52-61, 2018. [14] BS 882; - Specification for aggregates from natural sources for concrete, British Standards Institute. London, United Kingdom, 1992. [15] BS EN 196-6; - Methods of Testing Cement Determination of fineness, British Standards Institute. London, United Kingdom, 2010. [16] BS 12390-5; 2005 – Testing Hardened Concrete: Flexural Strength Test of Specimens, British Standards Institute. London, United Kingdom, 2005. [17] BS 12390-5; 2005 – Testing Hardened Concrete: Flexural Strength Test of Specimens, British Standards Institute. London, United Kingdom, 2005.
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