Interaction of Chemical, Physicochemical, and Geotechnical Soil Properties of Anambra State Gully Erosion Sites
Okeke C. H, Ubaoji K. I, Uzodinma F. C
Page Numbers : 10.36348/sjce.2021.v05i10.001
DOI : 379-390
Disturbed subgrade soil samples were collected from five (5) different erosion sites in Anambra State, Nigeria. In-situ and laboratory tests were conducted to ascertain the biochemical, physicochemical, and geotechnical properties of these samples. The topsoil characteristics were studied differently from the subsoil characteristics. All the samples considered were non plastic (from Atterberg limit tests). The result of relative size of soil particles in Anambra state reveals a higher mean values of sand when compared to silt and clay. The maximum dry density of the soil averaged (1858.19 ± 52.257) kg/m3 and (1866.986 ± 50.298) kg/m3 for the topsoil and subsoil respectively indicating high compaction values. The sodicity (Sodium Absorption Ratio and Exchangeable Sodium Percentage) of the soil was used to measure the dispersiveness of the soil, and the results show that Anambra state soils are highly dispersive, especially the topsoil. Hence, it is highly related to the erodibility of the soils in the zone considered. Furthermore, correlation analysis showed that there is a considerable correlation between geotechnical, physicochemical and biochemical properties of the soils in the state with the presence of sodium playing a major role in determining the influential properties.
Original Research Article
Oct. 14, 2021
Three-Dimensional Modeling of Waste Stabilization Pond with Computational Fluid Dynamics
Onosakponome OR, Dike BU, Ukachukwu OC
Page Numbers : 367-378
DOI : 10.36348/sjce.2021.v05i09.005
Waste stabilization ponds (WSP) are used extensively to provide wastewater treatment throughout the world. A review of the literature indicates that, understanding the hydraulics of waste stabilization ponds is critical to their optimization, the research in this area has been relatively limited and that there is a poor mechanistic understanding of the flow behavior that exists within these systems. This explains why there is no generally acceptable model for predicting its performance. The three-dimensional computational fluid dynamics (CFD) model developed in this study was extensively tested on the waste stabilization pond located in the campus of the University of Nigeria, Nsukka which was used as the field pond and also on a laboratory scale waste stabilization pond obtained from literature. Although the model may be solved by several methods, this research was limited to computational method; numerical solution using finite difference method was used in solving the three-dimensional partial differential equations at steady state conditions. In order to validate the quality of the model, its results were compared with the experimental data from the field and the lab-scale ponds. The results obtained were encouraging, prediction of pond performance with measured values shows that a correlation coefficients of (0.92 – 0.95) was obtained, representing an accuracy of 94%, an ultimate result that demonstrates that actual dispersion in the pond is three-dimensional. The 3-D model was then used in series of investigative studies such as; effect of single inlet and outlet structures at different positions in the pond, effect of multiple inlet and outlets on the pond’s performance, variation of pond performance with depth, effect of short-circuiting on pond treatment efficiency, effect of baffles on pond performance using laboratory-scale pond data and comparison with tracer studies. In all, the results were satisfactory.
Original Research Article
Oct. 6, 2021
Investigation of Water and Heat Response to the Compression Property of Raffia, Bamboo and Coconut Fiber-Reinforced-Polyester Composites
Obi, L. E., Uwanugo, R-G. Uchejiora
Page Numbers : 337-354
DOI : 10.36348/sjce.2021.v05i09.003
The dearth of construction materials has been the bane of the global construction industry. In a bid to curb this menace, it becomes very imperative to source for construction materials from discarded and least costly materials from raffia, bamboo and coconut fibers. This research investigates the hydrothermal response of plant fiber-reinforced-polyester composites (PFRC). Imperical methods were used to determine the mechanical properties of PFRC (bamboo, raffia and coconut fiber composites), with the usage of Monasanto Tensometer testing machine. All the samples were chemically modified with 12.5g of sodium hydroxide. Numerical and micro-soft excel graphics were used to model compressive responses of the PFRCs. From the analyses, the compressive strengths of raffia, bamboo and coconut composites are 40, 45 and 38MPa respectively.
Original Research Article
Oct. 6, 2021
Detection of Cracks in Heavy Weight Concrete Using Inner Electrical Resistivity Method
Mostafa Hassaan, Mohamed Ihab ELMasry, Nabil Hassan EL Ashkar
Page Numbers : 355-366
DOI : 10.36348/sjce.2021.v05i09.004
Nuclear power plants are considered as a vital structure in these days. Heavy weight concrete is used in radiation shielding for nuclear power plants which is characterized by high density of aggregate. Moreover, type of aggregate used in the concrete mix play an important role in obtaining heavy weight concrete. The coarse aggregate which is used in this research is hematite coarse aggregate. Small prisms were manufactured in the laboratory in order to measure the variation in electrical resistivity for heavy weight concrete prisms, one prism is uncracked and the other prism is manufactured with a vertical crack. The objective for this research paper is to detect the cracks using inner electrical resistivity for heavy weight concrete which contains hematite coarse aggregate. The two parameters which are used in detecting cracks are the percentage change in electrical resistivity and the second parameter is Decimal Logarithm Resistivity Anisotropy (DLRA). The inner electrical resistivity measurements were measured two concrete prisms by two methods, the first is linear inner electrical resistivity measurement (LIERM) and the other accurate one is the square inner electrical resistivity measurement (LIERM). This paper is concerned in detecting cracks especially the inner cracks which can’t be observed by naked eyes using non-destructive testing method such as inner electrical resistivity method. It was concluded that the inner electrical resistivity can be used efficiently for detecting inner cracks using the percentage change in electrical resistivity and DLRA which detect the presence of crack inside the small laboratory prisms efficiently.
Original Research Article
Oct. 6, 2021
Hydrothermal Response of Plant Fiber-Reinforced-Polyester Composites
Obi, L. E., Uwanugo, R-G. Uchejiora
Page Numbers : 325-336
DOI : 10.36348/sjce.2021.v05i09.002
This paper investigates the hydrothermal response of plant fiber-reinforced-polyester composites (PFRC). Experimental methods were used to determine the mechanical properties of PFRC (bamboo, raffia and coconut fiber composites) through the use of monasanto tensometer testing machine. All the samples were chemically modified through the use of 12.5g of sodium hydroxide. The ultimate tensile strengths and moduli of raffia, bamboo and coconut fiber -reinforced polyester composites were computed when the composites were subjected to 20, 40, 60 and 100oC temperature and also soaked in water for periods of 4,8,12 and 24 hours. Numerical and micro-soft excel graphics were used to model the tensile responses of the PFRCs. From the analyses, the ultimate tensile strengths and moduli of raffia, bamboo and coconut composites for 24 hours at 100oc are 4.3, 5.8, 7.7MPa and 0.1, 0.06, and 0.11GPa respectively.
Original Research Article
Oct. 5, 2021
Concrete Resistivity and Corrosion Potential Probability Measurement of Reinforced Concrete Structures using Electrochemical Methods
Charles Kennedy, Ebuka Nwankwo, Sylvester Obinna Osuji
Page Numbers : 305-324
DOI : 10.36348/sjce.2021.v05i09.001
Deterioration of reinforced concrete structures in marine environments is typically related to external retailers inclusive of chlorides that penetrate concrete causing harm. Corrosion products are relatively porous, susceptible, and often form around reinforcing metal, accordingly decreasing the bond between the reinforcement and concrete. This study evaluated the effect of using an extruded obtained from Perseus americana obtained from tree trunks as an inhibitor against corrosion attack on reinforced concrete structures in coastal zones with high salt concentrations and aggravated conditions. The extracted exudates/resin was coated to reinforcing steel and embedded in a concrete slab which is exposed to a corrosive medium with a high salt concentration The results of half-cell potential measurements maximum yields of the controlled and coated samples were -103.73 mV and -108.61mV, which showed the relationship between corrosion potential and probability in the Ecorr > 200mV as reference range. The potential results from Ecorr show that the value of the controlled and resin-coated sample with a 90% probability of no corrosion on reinforcing steel observed during the measurement is low (10% risk of corrosion, i.e. an average of 10% for the sample without coating gets the maximum value of -336.54mV, the result lies in the correlation reference value between the corrosion potential value of −350mV ≤ 𝐸corr ≤ −200mV, indicating a high-value range of 10% or indicating corrosion uncertainty. Comparatively, the results from the reference range (controlled) indicate that the sample is corroded due to the induced corrosion acceleration relative to the coated sample that the exudates/resin exhibits inhibitory properties against corrosion attack on reinforcing steel embedded in a concentrated re-plate which is exposed to a corrosive medium by forming a resistive layer. The maximum computed percentile of the controlled sample concrete resistivity is 66.23% compared to the corroded and coated values of -41.71% and 76.82% and the maximum controlled differential percentile is 2.71% compared to the corroded and coated value of 1.74 % and 5.28%. The results of the controlled and layered concrete resistance samples obtained the maximum average values of 15.2 kΩcm and 16.21 kΩcm with data values of 10 <𝜌 <20 (low) compared to the corrosion value of 9.21 kΩcm with Specifications 5 <𝜌 <10 (high) and with the reference range of the relationship between concrete resistance and corrosion probability, the corrosion probability was significant (𝜌 < 5, 5 < < 10, 10 << 20, > 20) for very high, high, low to moderate and low, for possible corrosion. From the comparative of coated and corroded samples, the maximum value obtained in both samples clearly shows the value of the coated sample with a range of 10 < 20, which classifies the range of values from low to moderate, with a significant indication of the possibility of corrosion. The maximum value of the corroded sample is in the range of 5 <10 which indicates high, signs indicating the presence of corrosion probability. The computed maximum percentile values of the controlled yield strength are 8.75% against corroded and the coated value of 7.2% and 8.81%, respectively, and the possible differential values are 0.05% controlled 0.89% corroded and 1.05 % coated. The controlled tensile strength is 2.885% compared to the corroded and coated values - 3.168% and 2.828% and the possible differential values are 0.19% controlled, 0.077% corroded and 0.039% coated. The comparative results show that the low load carrying capacity is caused by the effect of corrosion attack on the uncoated (corroded) elements, which damage the reinforcing steel fibers, ribs, and passive formation and surface modification. The maximum value computed from the percentile coated 0.049% against corroded -0.975% and 1.992%, the percentile differential in corroded 0.023% against coated 0.054%. For comparative, the results of the corroded samples showed reduction and reduction values compared to the diameter of the reinforcement before and after the induction accelerated corrosion test with a percentile range to reduce the value from 0.049% to -0.975% and the average value in the range of 11.95 mm to 11. 91 mm. The aggregate results show that the corrosion effect causes a reduction in weight/weight reduction in the corroded samples compared to coatings with a percentile exposure and an average increase, resulting in a small increase in the volume of the coating thickness.
Original Research Article
Sept. 27, 2021
Effect of Impact Boeing 707-320 on External RC Containment of Nuclear Power Plant for Different Compressive Strength of Concrete
Mostafa Hassaan, Mohamed Ihab ELMasry, Nabil Hassan EL Ashkar
Page Numbers : 282-304
DOI : 10.36348/sjce.2021.v05i08.004
External RC containment vessel of nuclear power plant is considered as a vital structure in the nuclear plant. The main function for the external RC containment is to prevent the escape of radiation into the external environment. The external RC containment of NPPs is subjected to impact of an aeroplane Boeing 707-320 acting on 16 exterior nodes at a vertical distance of 30m measured from the top of the foundation level. The problem in this research is the damage generated due to the impact of missile on external RC containment which can escape the radiation into the external environment. The response for RC containment was conducted with respect to stresses, displacement, velocity and acceleration after the impact. The objective is to increase the compressive strength of concrete in order to reduce the damage for RC containment due to impact of missile compared to concrete with a compressive strength of 30 Mpa. It was observed that the damage affects only the impact region of the RC containment. Parametric numerical modelling was conducted using ANSYS program for concrete having different compressive strength for external RC containment. It was observed that the effect of different compressive strength has a great result on the displacement, velocity and acceleration for RC containment due to impact of Boeing 707-320.
