GSJ: Volume 7, Issue 9, September 2019, Online: ISSN 2320 …...reinforcement on the concrete beam. Flexural strength failure loads of coated members with dacryodes edulis, ... Entire

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: [email protected],

[email protected] [email protected]

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

GSJ: Volume 7, Issue 9, September 2019 ISSN 2320-9186

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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


1156


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.


1157


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.


1158


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


460 460 460 460 460 460 460 460 460


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


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


79.304 80.254 79.604 79.644 80.004 79.834 79.604 79.644 80.144


(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


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


80.95111 52.30728 79.78178 154.7607 64.61589 152.5252 54.7607 -35.3841 52.5252


(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


460 460 460 100 100 100 0 0 0


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


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)




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)






1164


Figure 3.3: Ultimate Tensile Strength versus Strain Ratio of Beam Specimens


Figure 3.3A: Average Ultimate Tensile Strength versus Strain Ratio of Beam 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




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 (%)





1165


Figure 3.4: Ultimate Tensile Strength versus Elongation of Beam Specimens


Figure 3.4A: Average Ultimate Tensile Strength versus Elongation of Beam 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.

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Ult

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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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