Geotechnical Investigation of Pavement Failure: A Case Study of Sango Ota - Owode Expressway, Nigeria
Akanbi DO, Mlanga VT, Ekpo E, Egbo GN
Page Numbers : 274-281
DOI : 10.36348/sjce.2021.v05i08.003
This research work is premised on investigating the failing state of the Sango Ota- Owode expressway with design life of 20 years when it was first opened to traffic in 1974. It was reconstructed in 1993 through 2000 when it was fully opened to traffic again. However, it has become unserviceable with several deformations and deterioration all over the entire road. Eight soil samples were collected at the chosen failed sections and five soil samples at the good section for both sub-grade and sub-base, Twenty six samples all together. The soil samples were tested to determine the Atterberg limits, particle size distribution, compaction and California bearing ratio and the results were compared with the Federal Ministry of works and housing (1994) general specification. The Optimum Moisture Content (O.M.C) test result for the sub-grade and sub-base materials shows that none of the eight samples met the required criteria as their values were greater than the maximum of 7% specified. Only three samples of locations at Km 28+100 (o-s), Km 25+069 (o-s) and Km 24+000 (o-s) with values of 8%, 7% and 8% respectively, met the soaked CBR condition of at least 7%, while only two samples of locations at Km 28+100 (o-s) and Km 24+000 (o-s) with subgrade CBR values of 16% and 17%, met the unsoaked criterion. For the sub-base, only samples of location Km 25+069 (o-s) with value of 34% met the soaked CBR value of at least 30% while samples of locations at Km 28+100 (o-s) and Km 25+069 (o-s) with unsoaked CBR values of 80% and 82% respectively, which met the minimum 80% criterion for subbase. From the above undesirable results for the geotechnical investigation, reconstruction of the pavement is recommended.
Original Research Article
Sept. 6, 2021
Assessment of Change in Land Use Land Cover and Effect of it on Soil Loss from Phewa Watershed
Jaya Bahadur Bista, Keshav Basnet
Page Numbers : 259-273
DOI : 10.36348/sjce.2021.v05i08.002
Land use land cover change trend in Phewa watershed of Nepal was found very unsymmetric over the past two decades causing tones of soil loss from it. This research focused on providing some valuable insights related to land use land cover change and its effects on soil loss from Phewa watershed using the ArcGIS and RUSLE Model in conjunction with Remote Sensing data for the year 2000, 2005, 2010, 2015, and 2020. This study predicts that the settlement change rate in very intensive compared to other coverages. However, change rate for forest, agriculture, barren, and water was found noticeable. Highest rate of change for settlement land was found 128.40 ha/yr in 2005 to 2010 while for agriculture and forest land it was found 192.92 ha/yr and 181.88 ha/yr respectively in 2000 to 2005. For the barren land and water highest rate of change were 94.12 ha/yr and 12ha/yr respectively. The overall land use change from 2000 to 2020 for built-up area, agricultural land, forest area and bare land were found as 12.30 Km2 (342.20%), 6.47 Km2 (13.12%), 2.45 Km2 (4.27%), and 3.44 Km2 (39.13%) respectively. This research predicts that the fluctuation of land use change has great effects on the soil loss. The year interval having higher land cover change consisted with higher loss of soil and vice versa. Soil loss rate was found highest in 2010 (16.74 t/ha/yr) followed by its lowest rate in 2015 (11.58 t/ha/yr. Year interval with these two significant soil losses has high rate of LULC change. Additionally, this study forecasted the land use land cover change using MOLUSCE in QGIS for the year 2025 and 2030. Forecasted result showed that settlement area will maintain its coverage as 17.10 Km2 and 17.19 Km2 in 2025 and 2030 respectively. In 2025, forest and agriculture will maintain their coverage as 54.99 Km2 and 42.53 Km2 respectively followed by their coverage in 2030 as 55.10 Km2 and 42.39 Km2 respectively. The barren land will be 4.33 Km2 in 2025 but 4.25 Km2 in 2030 while the water coverage for both 2025 and 2030 years will be the same as 3.86 Km2. The results of this study could be very useful and could serve as a corner stone for the sustainable management of land use land cover and to control the soil erosion from the Phewa watershed.
Original Research Article
Sept. 5, 2021
Evaluation of the Compressive Strength of Bamboo Culms under Node and Internode Conditions
Omaliko Ifeanyi Kenneth, Ubani Obinna Uzodimma
Page Numbers : 251-258
DOI : 10.36348/sjce.2021.v05i08.001
Four samples of Guadua Angustifolia (Colombian Timber Bamboo) bamboo culms were investigated in this study in order to determine the effects of nodes and other physical properties on the compressive strength. The samples were categorized into two groups; samples with nodes (labeled 1M and 1G) and samples between nodes (internode) which were labelled 1J and 1B. The mechanical properties such as moisture content, density, modulus of elasticity and compressive strength of the samples were studied in the laboratory. From the results obtained, it was observed that the density of all the bamboo samples was directly proportional to their respective compressive strengths. Bamboo culm samples from the internode part had a compressive strength that is lower than that of those from the node part (1M and 1G). The culm sample from the node part (1M) had the highest compressive strength of 80.5379 N/mm2 while the culm sample from the internode part (1B) had the lowest compressive strength of 60.8930 N/mm2. The culm diameter, wall thickness and length influenced the cross-sectional area over which the stress was determined. Therefore, the mechanical properties of bamboo are dependent on its physical properties to a reasonable extent.
Original Research Article
Aug. 30, 2021
Evaluation of Pullout Bond Effects of Inhibitive and Non-Inhibitive Reinforcing Steel
Gwarah Ledum S, Kelechi Okwulehie, Charles Kennedy
Page Numbers : 236-250
DOI : 10.36348/sjce.2021.v05i07.005
The study examined the usefulness of exudates/resin extrudes from tree trunk as inhibitive material against corrosion attacks to reinforcing steel embedded in concrete structures and exposed to high levels of salt in coastal marine areas. The maximum recorded average and percentile values are controlled 45.546% against corroded and coated values of 36.881% and 78.747% and with differentially potential values of the bond strength controlled 1.409MPa and 19.437% against corroded values of 0.276MPa and 7.174% and coated values 1.409MPa and 20.317%. The lower load failure characteristic has been attributed to the effect of corrosion attack resulting in rib-less (smooth) and surface modification, the effect of corrosion resulted to the swollen surface with peeled off fibre while coated samples exhibited highly resistive characteristics to corrosion attacks showing the effectiveness of exudates/resin as an anti-corrosive material in curbing the scourge and menace faced by reinforced concrete structures built in the coastal the marine region with unique and severe characteristics of high salinity. Comparatively, obtained results showed decreased slippage failure load exhibition by the corroded samples over the controlled and coated samples with a highly lower value range to the reference with coated samples exhibiting higher slippage failure load with increased values over-controlled. From the result of average values and percentile values difference, the failure bond load, bond strength, and maximum slip all failed at low load applications with decreased percentile values compared to controlled and coated concrete cube samples. This reduction in rebar diameter and the cross-sectional area has resulted in higher failure bond loads, lower bond strengths, and lower slippages, and these characteristics revealed the effects of corrosion on the reinforcing steel that resulted from surface modification, reduction of rebar fibre, and high yield to load applications. From the results obtained and presented in the figures, the effect of corrosion on uncoated and coated reinforcing steel are enumerated, in figures 3 and 6b on the diameter of rebar, it can be seen that the diameter of uncoated decreased by the maximum value of -0.841% and coated increased by 0.922%, for the cross-sectional area, corroded has maximum reduction value -20.649% and coated increased by and 26.022%, weight loss, and gain are corroded -19.905% decreased (loss) and coated 36.334% increase (gain).
Aug. 30, 2021
Sheltering Execution Printable Plan in Jordan
Mohanad Akeila, Kelvin Kuok King Kuok, Christopher Preece
Page Numbers : 212-221
DOI : 10.36348/sjce.2021.v05i07.003
The sheltering execution plan of a 3D printed shelter is planned to demonstrate the design of an existing camp, but it is built using printable sheltering units rather than tents and prefabricated cabins. The Zaatari Refugee camp in Jordan is selected as a case study for multiple reasons. The Zaatari Camp is located in Jordan, and was established on a large scale within short notice. The camp is built in a country ranked as one of the most expensive in the Middle East. The economy of the country and the needs of refugees make it an attractive case study to implement printable sheltering units, allowing for the investigation of the performance of a printable camp against existing sheltering camps covering aspects of time, cost, occupancy, and implementation perspectives. Achieving positive performances of a printable camp in Jordan will ensure that camps will be suitable and affordable in other countries with stronger economies, along with cheaper construction rates. The 3DP shelter is found to be a cost-effective solution in Jordan, which means that the printed shelters can achieve higher cost efficiency measures in less expensive countries in the Middle East, such as Turkey.
Original Research Article
Aug. 30, 2021
Friction Force Reduction of Corroded and Exudates Coated Reinforcing Steel Exposed to Severe Media
Gregory C. Ezeokpube, Charles Kennedy, Michael Ebie Onyia
Page Numbers : 222-235
DOI : 10.36348/sjce.2021.v05i07.004
The performance of reinforced concrete structures, as in other composite members, depends on the bond between the steel and the concrete which ensures that load is transferred safely between the two materials. The research involved the direct application of environmentally and eco-friendly extracted exudates/resins used to control the effect of corrosion attacks by coating steel with varying thicknesses, embedded in concrete structures and immersed in sodium chloride (NaCl) solution for corrosion accelerated process. Laboratory experimental samples reflected the acid level of sea salt concentration in reinforced concrete cubes. The data for comparison of maximum obtained values are failure bond load are corroded -41.594% against 78.166% and 80.194% controlled and coated, bond strength is -34.227% against 73.201% and 69.943% and maximum slip are -42.731% against 102.034% and 113. The summarized computed and compared results of failure bond load, bond strength and maximum slip of the controlled, corroded and coated samples showed that the effect of sodium chloride as detailed in the "2.2 Experimental procedures" has adversely affected the mechanical properties of reinforcing steel of uncoated (corroded) samples which has resulted to poor performances, low load at failure state, less bond strength and slippage. The coated samples exhibited the potential of sustaining the negative effect of corrosion on reinforcing steel and by forming good contact and interlock between concrete and reinforcing steel by reducing the stress existing in the concrete surroundings. Results showed that the diameter of corroded reinforcement decreases by a maximum of -0.771% and the coated increases by 0.831%, for the cross-sectional area corroded has a maximum reduction value of -13.163% and the coated increases by 20.74%, the weight loss and increase in corroded is -22.887 % decreased (loss) and coated increased by 34.929% (gain). Regarding the mechanical properties of reinforcing steel, the effect of corrosion on reinforcing steel shows a decrease in the cross section of the rebar diameter compared to the nominal diameter before testing, weight reduction is also observed, an increase in the cross-sectional area, an increase in the diameter and minute increase in weight resulting from coating material as compared with the nominal reinforcement, which is due to differences in the thickness of the layered materials. It can be concluded that the exudate / resin studied has shown effective inhibiting properties against corrosion attack and can be used as a corrosion inhibitor
Original Research Article
Aug. 21, 2021
Structural Residual Strength Performance of Corroded and Inhibited Reinforced Concrete Structures in Corrosive Media
Gabriel Okonkwo Nnaji, Eze Chinonso Emmanuel, Charles Kennedy
Page Numbers : 192-211
DOI : 10.36348/sjce.2021.v05i07.002
This study evaluated the naturally extruded exudates/resin from plants of inorganic origin with eco-friendly and environmentally non-hazardous materials derived from tree trunks. Exudates/viscous adhesive is then embedded into the concrete beam after layers of different thickness and applied directly to the steel reinforcement. This study further aimed to determine the role of exudates/resins in harmful attacks on reinforcement by water tightness and durability (resistance) and modifications of steel reinforcement surface due to coating. In comparison, the results of the flexural strength exhibited at the maximum for the controlled sample is 27.86% compared to the corroded with -20.75% and coated sample of 27.87%, respectively. Differential mean values and percentile ranges were checked to be (0.55kN and 1.43%) for the controlled, (0.66kN and 1.04%) corroded and (0.52kN and 1.69%) coated. Corroded specimens fail with a lower load applications and high yielding, whereas coated specimens have a higher load to failure and lower yield occurrence. The results further confirmed that the flexural failure loads of the controlled and coated specimens maintain a narrow range of values over the corroded specimens at moderate, reduced and lower loads. The comparative results showed that the maximum value of the controlled state is -38.58% compared to 63.61% corroded and controlled -37.96%. The recorded mean and percentage difference values were examined and computed to be (0.26kN and 0.93%), corroded (0.26kN and 2.42%) and coated (0.27kN and 0.92%). The results showed a lower failure deflection load in the controlled and coated samples with a reduced value over the corroded sample with a higher failure deflection load and an increasing value compared to the reference range (controlled) and the layered (coated) sample. The comparative obtained results during and after the corrosion test for the maximum value of the rebar diameter is 0.53% compared to the corroded -0.74% and the coated sample 0.85%. The computed mean differential and percentile values were (0.02% and 0.03%), the corroded values were (0.03kN and 0.11%) and the coated values were (0.01kN and 0.11%). The results showed the effect of corrosion on the mechanical properties of reinforcing steel with a smaller diameter, where the average value and the percentage of corroded samples decreased, while the controlled and coated samples showed a preserved condition, with an increase in the diameter of the coating emanating from the varying coating thicknesses from the exuates /resin. The cross-sectional area of the reinforcing steel mean and percentile values calculated from the corroded values are (0.02 and 6.19%) and the coated values (0.02 mm and 5.21%). The results obtained showed the effect of corrosion on the mechanical properties of reinforcing steel with a decrease in the diameter of the reinforcement in the corroded sample, while the coated sample showed an increase in the thickness of the exudate paste layer. The differential calculated average and percentage yield strength and ultimate tensile strength (6.93MPa and 5.46%) and (2.53MPa and 0.02%), the corrosion value was (2.81 MPa and 5.01%) and (2.53 MPa and 0.02%). the values covered are (3.98MPa and 5.46%) and (2.56MPa and 0.01%). From the data obtained and compared, the yield strength and tensile strength values of the corroded sample take into account the mean and percentile values reduced with load damage with low application. The comparative strainn ratio obtained from the calculated maximum values for the mean and percentile values for the control was -3.19% compared to the corroded and overlaid values of 3.29% and -2.88%, respectively. The mean differential and percentile values obtained for the control were (0.42 and 0.3%), corroded values (0.42 and 0.32%) and closed values (0.43 and 0.31%). The results showed that the corroded sample had a higher percentage of deformation due to lower breaking load and higher yield strength, while the coating had a higher breaking load with lower yield strength. The calculated data for the maximum percentage of reinforcement weight before corrosion test for controlled, corroded and coated values were 0.05%, 0.05% and 0.07%. The maximum comparison values recorded after the corrosion test for the controlled sample remained the same, with no trace of a corrosive effect, as it was collected in fresh water, for the corroded and coated samples the values obtained were -6.82% and 7.76%, respectively.