ORIGINAL RESEARCH ARTICLE | Aug. 6, 2021
Corrosion Resistance Potential Bond-slip Mechanisms of Reinforcing Steel in Corrosive Media
Sornaate Lucky Easy, Ugo Kingsley, Charles Kennedy
Page no 214-226
This study investigated the potential use of eco-friendly material of organic classes to curb the menace of corrosion effect on reinforcing embedded in concrete structures and exposed to corrosive media. The obtained results of 36 concrete cubes; 12 controlled, 12 uncoated (corroded) and 12 exudates / resins coated cured for 360 days under freshwater and induced corrosion accelerated process as detailed in experimental procedures. From the computed results, the maximum obtained value of the corroded sample is -39.551% as against 78.562% and 82.183% of controlled and coated samples respectively. The results showed decreased failure bond load in corroded sample and an increase in coated judging from controlled sample as a standard for comparison. The results of bond strength maximum obtained values are corroded -29.789% against controlled 35.831% and 67.905%, enumerative results showed low and decreased bond strength of corroded samples resulted from the effect of corrosion damaged to the reinforcing surface and fibre. Higher bond strength obtained from coated samples resulting from the gummy and sticky exudates/resin that formed higher bonding with the rib. Results of slippage in controlled and coated samples showed higher values to failure as against lower slippage in coated. Results indicated that the diameter of uncoated decreased by maximum value of -1.293% and coated increased by 1.31%, results showed that reduction is attributed to the effect of corrosion on the surface modification through the formation of pits and unusual expansion, also similar factor is applicable on the cross - sectional area, corroded has maximum reduction value of (-7.414% and coated increased by 14.934%, weight loss and gain are corroded -28.567% decreased (loss) and coated 48.006% increase (gain). Summarized results showed the effect of affected the overall mechanical properties of reinforcing steel thereby reducing bond characteristics of steel and concrete by creating stresses in the surroundings and further weakened pullout bond resulting in diameter and cross – sectional area reduction and weight decreased. The effect of coating increased diameter and cross – sectional area and weight gain resulting from the varying thickness coated to reinforcing steel.
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ORIGINAL RESEARCH ARTICLE | Aug. 17, 2021
Evaluating Parameters Affecting the Performance of the Spark Ignition Engine
Akinfaloye OA, Onwuamaeze IP
Page no 232-241
An experiment work has been carried out to evaluate the parameters affecting a one cylinder engine (spark ignition engine) at two throttle positions (1/2 throttle and full throttle) for two stroke engine and at three throttle positions (1/2 throttle, 2/3 throttle and full throttle) for four stroke engine. Parameters such as brake power, BMEP, Brake thermal efficiency and specific fuel consumption where considered at varying speeds (780, 1560, 2340, 3120 and 3900rpm) and (1000, 1200, 1400, 1600 and 1800rpm) for two stroke and four stroke respectively. The results obtained showed that the brake power, brake mean effective pressure and brake thermal efficiency increases while the torque, specific fuel consumption and volumetric efficiency decreases as the engine speed increases when considering the three throttle positions. The volumetric efficiency and brake power of the two stroke engine for the half throttle positions at 4680rpm for two stroke were 0.229 and 7.545kw respectively compared to the full throttle positions which were 0.299 and 7.662kw respectively. The volumetric efficiency and brake power of the four stroke engine for the half throttle positions at 1800rpm for two stroke were 0.180 and 5.598kw respectively compared to the 2/3 and full throttle positions which were 0.1803, 8.2073kw and 0.1803, 9.2026kw respectively.
ORIGINAL RESEARCH ARTICLE | Aug. 21, 2021
Chemical Thermodynamics Determination of Corrosion Threshold Assessment of Reinforced Concrete Structures
Achieme Lewis Oba, Charles Kennedy, Gbinu Samuel Kabari
Page no 242-258
The study evaluate the scourge of corrosion effects on reinforcing steel with the application Calotropis procera exudates / resin coated directly in different thicknesses to reinforcing steel, embedded into concrete slabs and exposed to coastal waters with a high concentration of salt to curb the rate and degree of corrosion. The hardened concrete slab is fully immersed in 5% sodium chloride (NaCl) solution for 360 days, with interval inspection and routine tests at 90 days, 180 days, 270 days and 360 days. The maximum calculated percentile control value is -59.22% compared to the corroded and coated values of 229.5% and -59.22% and the controlled potential difference value is 8.8%, 84.28% corroded and 10.43% coated. The maximum yields of the controlled and coated samples were -105.37mV and -122.66mV 6mV, which showed the relationship between corrosion potential and opportunity in the reference range 𝐸corr > −200mV. Corrosion potential probability values of uncoated samples has maximum calculated range of -308.77mV, the result is within the reference value of dependence between corrosion potential and probability of value −350mV ≤ 𝐸corr ≤ −200mV indicates a high range of values, which is 10% or uncertain probability of corrosion. Results in comparison from the reference range (controlled), it is observed that show that non-coated samples showed corrosion potentials with higher values as a result of accelerated corrosion induced as compared to coated samples. The maximum value calculated from the concrete resistance of the controlled sample is 111.34% compared to the corroded and coated value of -54.53% and 135.59% and the maximum value of the percentile difference from the control is 19.17% compared to the corroded and coated value of 3 0.02% and 15.66%. The results of testing controlled samples coated with concrete resistance obtained the maximum average values of 15.28 kΩcm and 17.53kΩcm with a description of the value 10 < 𝜌 < 20 (low) compared to the corrosion value of 7.9kΩcm with specifications 5 < 𝜌 < 10 (high) and with a reference range of dependence between concrete resistance and corrosion probability at significant corrosion probability. The calculated maximum percentage of the controlled yield strength was 8.31% compared to the corroded and coated values -7.35% and 8.66% and the possible difference values of 0.45% controlled, 0.62% corroded and 0.72% coated. The calculated maximum percentage of the controlled of ultimate tensile strength is 1.99% relative to corroded value of -2.69% and the coated values of 2.78%% and with differential potential values of 0.01% controlled, 0.01% corroded and 0.01% coated. Comparatively, corroded samples exhibited high yielding to low load application representing the effect of corrosion on the mechanical properties of reinforcing steel that has resulted to low load carrying capacity, the corroded also recorded higher strain ratio as compared to the coated to the parameters above. The maximum calculated percentage was set at 0.929% versus corroded - 0.919% and coated at 1.043%, with a percentage difference in corrosion of 0.004% versus 0.067% coated. For comparison, the results of the corroded samples showed a reduction values compared to the diameter of the reinforcement before and after the induction accelerated corrosion test with a percentage decrease in value from 0.048% to -0.919% and an average value in the range from 11.96mm to 11.91mm. Comparatively, the results obtained show a reduction of the mean and percentile values for corroded from 0.07 kg to 0.05 kg and 35.19% to -23.61%. The summary results show that the corrosion effect on corroded samples causes a decrease in weight compared to coatings with percentile values and an increase in mean values, which causes a slight increase in volume with coating thickness.
ORIGINAL RESEARCH ARTICLE | Aug. 21, 2021
Wenner Probe Technique Application in Electrical Resistivity and Corrosion Potential Measurements of Concrete Induced Chloride threshold Mechanism
Macmammah Michael, Charles Kennedy, Achieme Lewis Oba
Page no 259-274
The research evaluated Musanga cecropioides extrusion viscosity gummy paste (exudate/resin) obtained from trees as a corrosion inhibitor material to slow down the impact of corrosion on steel bars embedded in concrete and constructed in high-salinity coastal areas. The exudates/resin extracted is coated on the steel bar and embedded in the concrete slab, exposed to the corrosive medium with high salt concentration. The hardened concrete slab is completely immersed in a 5% aqueous sodium chloride (NaCl) solution, and the rapid corrosion process accelerated for 360 days with interval inspections and routine tests at 90 days, 180 days, 270 days, and 360 days for comparative evaluations for both uncoated and coated samples. The computed maximum control percentile value is -67.28% compared to the corroded and coated values 241.14% and -64.4% and the controlled potential difference value is 4.99%, corroded 60.25%, and coated 6.29%. The maximum yields of the controlled and coated samples were -105.1mV and -113.74mV, with the result obtained, this showed an indicative relationship between corrosion potential and probability as 𝐸corr > −200mV as the reference range. These results of potential Ecorr results showed indication that the values of controlled and exudates/ resin coated specimens are low with the range of 90% probability that no reinforcing steel corrosion is occurring in that area at the time of measurement (10% risk of corrosion which indicates a 10% or uncertain probability of corrosion. For the non-coated sample, the maximum obtained computed value is -328.64mV, the results are within the range reference of dependence between potential and corrosion probability of the value −350mV ≤ 𝐸corr ≤ −200mV indicating a high range of values, notifying a 10% or uncertain probability corrosion. The comparative results from the referencing range (controlled), showed that corroded samples exhibited corrosion presence resulting from the induced corrosion acceleration against coated samples that exhibited absence of corrosion. The exudates/resins exhibited inhibitory characteristics against corrosion attacks on reinforcing steel embedded in the concrete slab, exposed to corrosive media by the formation of the resistive coating. The maximum computed percentile of the controlled sample of concrete resistivity is 149.21% compared to the corroded and coated value of -59.26% and 153.52% and the maximum percentile difference of control is 5.38% compared to the corroded and coated value of 1.3 % and 8.09%. The results of the controlled and coated concrete resistivity samples obtained at an average maximum value of 15.85kΩcm and 16.23kΩcm with a data value of 10 <𝜌 <20 (low) compared to a corrosion value of 6.45kΩcm with specifications (𝜌 < 5, 5 < 𝜌 < 10, 10 < 𝜌 < 20, 𝜌 > 20) and with the reference range of the relationship between concrete resistivity and corrosion probability, the significant corrosion probability (𝜌 < 5, 5 < 𝜌 < 10, 10 < 𝜌 < 20, 𝜌 > 20) was very high, high, low to medium and low, for corrosion probability. The computed maximum percentile of the controlled yield strength is 8.96% compared to the corroded and coated values -7.83% and 9.08% and the possible difference values are 0.45% controlled, 0.49% corroded, and 0.59% coated. The maximum computed difference in values is 1.83MPa and 0.01% the controlled tensile strength is 3.478% against the corroded and coated values, respectively are -2.942% and 5.408% and the potential difference values 0.01% controlled, 0.01%% corroded and 0.01% coated. The yield strength, tensile strength, and strain ratio of the mean, percentile, and differential potential values of the control, uncoated (corroded) and coated concrete slab samples showed that coated samples had higher failure loads compared to corroded samples with reduced and decreased failure loads and low load-bearing capacity and with average values and percentiles to the reference range, while uncoated (corroded) samples recorded lower loads carrying capacity and reduced value compared to the reference range. The diameter of reinforcement after corrosion maximum computed percentile value is 0.039% as against -1.116% corroded and 1.128% coated; the difference in percentile is 0.005% corroded versus 0.008% coated. The results of the comparative of corroded samples show the reduction in values compared to the diameter of the reinforcement before and after the induction accelerated corrosion test with a percentile range for the reduction value from 0.039% to -1.116% and the average value in the range from 11.99mm to 11.94mm. The decrease/increase (diameter) in the cross-section of the minimum and maximum mean and percentile values were controlled 100%, with no decrease or increase in the description after 360 days of immersion in fresh water. The decrease in mean and percentile values indicates that the corrosion effect causes a reduction in diameter and cross-sectional area, fiber degradation, ..........
ORIGINAL RESEARCH ARTICLE | Aug. 30, 2021
Performance Characteristics of Clove Oil, Eugenol and Eugenyl Acetate as Bio-Additives in a Single Cylinder Diesel Engine
I.M. Hadi, I.S. Sintali, H. Dandakouta, A. Tokan
Page no 275-289
The performance of the fuels blends and emission levels were investigated under various operating conditions of the engine. Performance parameters like torque, brake power, brake thermal efficiency and brake specific fuel consumption (BSFC) were studied. Also, carbon dioxide (CO2), carbon monoxide (CO), hydrocarbon (HC), oxides of nitrogen (NOx), oxides of sulfur (SOx) emissions and exhaust gas temperature were investigated. The tests were carried out on a horizontal single-cylinder, 4-stroke, air-cooled, 4.00 kW engine, TD115 model. The results showed that blend of diesel and eugenyl acetate (BDEA 1.0%, 0.6% and 0.2%) gave the best performance in terms of reduced exhaust emission. The test results showed that, with decreasing speed, the torque of the engine fueled with both diesel and the blends increased with the maximum torque was recorded at 1680 rpm engine speed for BDE 0.2%. Also, there was a considerable increase in exhaust temperature with the blends compared to the diesel. The exhaust gas temperature of BDC 0.2%, 0.6%, 1.0%, BDEA 0.2% and BDEA 1.0% appeared to be similar to that of the diesel at all speed conditions. The research reveals that for a constant load of 1000 g, brake power increases with the increase in engine speed, thus a maximum brake power of 1.9 kW was obtained at 1680 rpm for BDEA 0.2%, this confirmed the results reported by researchers. There was an increase in the engine’s brake thermal efficiency when run on diesel and all the fuel blends at all speed conditions; however, BDEA 0.2% and BDEA 0.6% exhibited better combustion quality than diesel. The BSFC of the blends varied with the engine power and speed; therefore, for all the blends and diesel, consumption was high at low speed and vice-versa. The results also showed that the blends gave less CO compared to diesel. The minimum and maximum reduction of CO were 1.0 % and 1.5 % respectively of the blends, as compared to diesel. The emissions of NOx, SOx and CO2 decrease with increase in clove oil, eugenol and eugenyl acetate in the blends. All the findings compared favorably with the results of other researchers.
ORIGINAL RESEARCH ARTICLE | Aug. 30, 2021
Electrochemical Techniques Assessment of Chloride Threshold for Reinforcing Steel Corrosion in Concrete Structures
Kelechi Okwulehie, Kpegara Saana N, Charles Kennedy
Page no 290-306
Corrosion of steel reinforcement in reinforced concrete is one of the most significant problems affecting structures and infrastructure worldwide, especially coastal structures. This study investigated the direct application of exudates/resin extract of Lannea coromandelica as a potential inhibitive material to control and prevent the corrosion of steel bars embedded in concrete structures and exposed to high salinity and acidic prone environments. The extruded exudates / resin is extracted from the tree and layered to reinforcing steel of different thicknesses. The hardened concrete slab is completely immersed in a 5% sodium chloride (NaCl) aqueous solution for 360 days with routinely checks, monitors and tested for 90 days, 180 days, 270 days, and 360 days of accelerated and corrosion process for comparative evaluation of both uncoated and coated samples. The maximum corrosion potential yields from the controlled and coated samples were -109.24mV and -114.16mV, indicating the relationship between corrosion potential and corrosion probability in the reference range 𝐸corr > −200mV. For non-coated samples, the calculated maximum value is -333.97mV, the result is within the reference value of the relationship between corrosion potential and corrosion probability of −350mV ≤ 𝐸corr ≤ −200mV indicates a high value range of 10% or less. The maximum calculated value of the controlled sample concrete resistance is 138.35% compared to the corroded and coated values of -56.56% and 153.43% and the maximum value of the control percentile difference is 24.97% compared to the corroded and coated value of 3.98% and 23.22%. The results of the controlled and layered concrete resistance samples obtained a maximum average value of 15.01kΩcm and 16.17kΩcm with a value of 10 < 𝜌 < 20 (low) compared to a corrosion value of 7.01kΩcm with a specification of 5 < 𝜌 < 10 (high) and with a reference range of the relationship between concrete resistance and corrosion probability and significant corrosion probability. The maximum computed percentile values of yield strength of controlled are 9.42% against corrode and coated values -8.03% and 9.57% respectively and the potential differential values of 0.71% controlled 0.71% corroded and 0.84% coated. The maximum computed percentile values of ultimate tensile strength of controlled are 1.68% against corrode and coated values -2.98% and 3.07% respectively and the potential differential values of 0.01% controlled, 0.00%% corroded, and 0.01% coated. Comparatively, the results of corroded samples showed reduction and decreased values in comparison of rebar diameter before and after induced accelerated corrosion test with values reduction percentile range from 0.038% to -0.895% and average ranges values from 11.98mm to 11.93mm. The reduction in average and percentile values showed that corrosion effects caused diameter reduction and cross-sectional area, fibre degradation, ribs reduction, and surface modifications whereas, exudates/resin coated members showed volumetric increase resulting from varying coating thicknesses. Conclusion: Summarized results showed that the effect of corrosion caused weight reduction/decreased in corroded samples as compared to coated with an exhibition of percentile and average value increase resulting in a volumetric minute increase from coating thicknesses.