A. S. Buhari, A. S. Abdulrahman, S. A. Lawal, A. S. Abdulkareem, R. A. Muriana, O. T. Jimoh, H. K. Ibrahim
This study examined the impact of synthesis parameter on Cobalt-Molybdenum supported with magnesium oxide (Co-Mo/MgO) catalyst yield in production of multiwall carbon nanotube (MWCNT). Wet impregnation was used to synthesis the Co-Mo/MgO bimetallic catalyst, while a catalytic chemical vapour deposition reactor (CCVD) was used for the synthesis of carbon nanotubes (CNTs). Factorial and central composite design techniques were used to optimise the catalyst and multi-wall carbon nanotubes (MWCNTs). Thermogravimetric analysis/ Differential thermal analysis (TGA/DTA), selected area (electron) diffraction (SAED), X-Ray diffraction analysis (XRD), and Brunauer–Emmett–Teller (BET) were used to characterise the catalyst and MWCNTs that were produced. The Co-Mo/MgO catalyst had an optimal yield of 93.22%, 247.30 m2/g of specific surface area at 120 °C drying temperature, 16 g of mass support, and a 10-hour drying time. The maximum catalyst yield of 40.62% was obtained at calcination temperature of 500 °C and a holding period of 2 hours. The catalyst with the highest degradation temperature of 398.21 °C was observed at 600 °C, when calcined for 4 hours. It was discovered that the surface area of Co-Mo/MgO catalyst from the BET analysis under ideal conditions varied depending on the holding time. The XRD and SAED revealed the growth of CNTs of concentric graphene pattern with the Co-Mo/MgO catalyst.
{"title":"Optimisation of synthesis parameters for Co-Mo/MgO catalyst yield in MWCNTs production","authors":"A. S. Buhari, A. S. Abdulrahman, S. A. Lawal, A. S. Abdulkareem, R. A. Muriana, O. T. Jimoh, H. K. Ibrahim","doi":"10.4314/njtd.v20i2.1409","DOIUrl":"https://doi.org/10.4314/njtd.v20i2.1409","url":null,"abstract":"This study examined the impact of synthesis parameter on Cobalt-Molybdenum supported with magnesium oxide (Co-Mo/MgO) catalyst yield in production of multiwall carbon nanotube (MWCNT). Wet impregnation was used to synthesis the Co-Mo/MgO bimetallic catalyst, while a catalytic chemical vapour deposition reactor (CCVD) was used for the synthesis of carbon nanotubes (CNTs). Factorial and central composite design techniques were used to optimise the catalyst and multi-wall carbon nanotubes (MWCNTs). Thermogravimetric analysis/ Differential thermal analysis (TGA/DTA), selected area (electron) diffraction (SAED), X-Ray diffraction analysis (XRD), and Brunauer–Emmett–Teller (BET) were used to characterise the catalyst and MWCNTs that were produced. The Co-Mo/MgO catalyst had an optimal yield of 93.22%, 247.30 m2/g of specific surface area at 120 °C drying temperature, 16 g of mass support, and a 10-hour drying time. The maximum catalyst yield of 40.62% was obtained at calcination temperature of 500 °C and a holding period of 2 hours. The catalyst with the highest degradation temperature of 398.21 °C was observed at 600 °C, when calcined for 4 hours. It was discovered that the surface area of Co-Mo/MgO catalyst from the BET analysis under ideal conditions varied depending on the holding time. The XRD and SAED revealed the growth of CNTs of concentric graphene pattern with the Co-Mo/MgO catalyst.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136359841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. S. Ayanninuola, U. D. Msughter, C. O. Ofoegbu, E. D. Uko
A geophysical investigation was carried out using Vertical Electrical Sounding (VES) in part of North Central Nigeria to evaluate the subsoil thickness, competence, and corrosivity for civil engineering foundations. A total of 60 VES stations were covered within the study area using the Schlumberger configuration array with half current electrode separation (AB/2) varying from 1m to a maximum of 100m while the half potential electrode spacing (MN/2) varied by 0.3 m to a maximum of 5m. The analysis of data was done using IP2win and Surfer 12 softwares. The first layer has resistivity values between 4.728 Ωm to 4210 Ωm and varied in thickness between 0.15 m to 1.42 m, the second layer has resistivity values between 24.7Ωm to 355000 Ωm and varied in thickness between 0.0355 m to 8.983 m while the third layer has resistivity values ranging between 8.361 Ωm to151,608 Ωm and varied in thickness between 1.05 m to 34.2 m, the fourth layer which is the last of the geoelectric layers has resistivity values between 27.95 m to 77000 m. The subsoil within the study area is composed of clay, sandy clay, clayey sand, sand, and laterite. From the qualitative interpretation of the Isoresistivity and Isopach maps, the Southwestern, Southeastern and Northwestern parts of the study area are moderately corrosive to extremely corrosive subsoil with resistivity values ranging between 4.728 Ωm and 50.48 Ωm. The third layer consists of an incompetent low resistivity soft material that underlain the entire study area except at the central region which is essentially noncorrosive and highly competent. VES curves interpretations revealed the thickness and depths of the geoelectric layers within the study area. The results of this research could enable civil engineers to ascertain the requisite depth of soil evacuation for the sustainability of structures within the study area.
{"title":"Characteristics of soils for civil engineering foundations in part of North Central Nigeria, using electrical resistivity method","authors":"O. S. Ayanninuola, U. D. Msughter, C. O. Ofoegbu, E. D. Uko","doi":"10.4314/njtd.v20i2.1261","DOIUrl":"https://doi.org/10.4314/njtd.v20i2.1261","url":null,"abstract":"A geophysical investigation was carried out using Vertical Electrical Sounding (VES) in part of North Central Nigeria to evaluate the subsoil thickness, competence, and corrosivity for civil engineering foundations. A total of 60 VES stations were covered within the study area using the Schlumberger configuration array with half current electrode separation (AB/2) varying from 1m to a maximum of 100m while the half potential electrode spacing (MN/2) varied by 0.3 m to a maximum of 5m. The analysis of data was done using IP2win and Surfer 12 softwares. The first layer has resistivity values between 4.728 Ωm to 4210 Ωm and varied in thickness between 0.15 m to 1.42 m, the second layer has resistivity values between 24.7Ωm to 355000 Ωm and varied in thickness between 0.0355 m to 8.983 m while the third layer has resistivity values ranging between 8.361 Ωm to151,608 Ωm and varied in thickness between 1.05 m to 34.2 m, the fourth layer which is the last of the geoelectric layers has resistivity values between 27.95 m to 77000 m. The subsoil within the study area is composed of clay, sandy clay, clayey sand, sand, and laterite. From the qualitative interpretation of the Isoresistivity and Isopach maps, the Southwestern, Southeastern and Northwestern parts of the study area are moderately corrosive to extremely corrosive subsoil with resistivity values ranging between 4.728 Ωm and 50.48 Ωm. The third layer consists of an incompetent low resistivity soft material that underlain the entire study area except at the central region which is essentially noncorrosive and highly competent. VES curves interpretations revealed the thickness and depths of the geoelectric layers within the study area. The results of this research could enable civil engineers to ascertain the requisite depth of soil evacuation for the sustainability of structures within the study area.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136359117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abdulganiyu Yusuf, Romoke Ojo, Mohammed O. Idrees, Abdul-Lateef Balogun, Isa B. Salami, Ojogbane S. Sani
Ilorin City is located downstream of Asa, Oyun and Awun River Basins. The Asa River is a major river that traverses the city and divides the metropolitan area into east and west, almost equally. The river often overflows its banks to inundate adjacent communities, influencing severe economic damage and impact on human lives. However, efforts to mitigate this have majorly been focused on dredging the Asa River channel which has not solved the problem. For an accurate spatial and temporal understanding of the risks of floods and their potential hazards, it is important to estimate floods using river hydrology. The objective of this study is to model steady flow of the rivers using flow data and to map flood-prone areas in Ilorin using HEC-RAS integrated with GIS. Using the HEC-GeoRAS extension in the GIS environment, the geometric data of the rivers were obtained from the 30 m resolution digital elevation model (DEM) and input into HEC-RAS applying Manning Co-efficient values of 0.04, 0.045, and 0.04. For each river, flow data (Q) was given as the upstream boundary condition while a normal depth of 0.001 was assigned for the downstream condition to model a steady flow and inundation extents. The result of the HEC-RAS model has shown the flood-prone areas along the river channels delineated. The floodplain map produced reveals the spatial distribution and extent of the high flood-risk areas in the Ilorin metropolis. The total flooded area covers approximately 60.95 km2 (18%) majorly along the river channels. This study has demonstrated that integration of hydraulic modelling using HEC-RAS and GIS process is capable of producing an inundation flood map with good accuracy that will aid in suggesting effective measures to mitigate the impact of flooding.
{"title":"Modelling flood hazards impacted by ungauged river in urbanised area using HEC-RAS and GIS","authors":"Abdulganiyu Yusuf, Romoke Ojo, Mohammed O. Idrees, Abdul-Lateef Balogun, Isa B. Salami, Ojogbane S. Sani","doi":"10.4314/njtd.v20i2.1405","DOIUrl":"https://doi.org/10.4314/njtd.v20i2.1405","url":null,"abstract":"Ilorin City is located downstream of Asa, Oyun and Awun River Basins. The Asa River is a major river that traverses the city and divides the metropolitan area into east and west, almost equally. The river often overflows its banks to inundate adjacent communities, influencing severe economic damage and impact on human lives. However, efforts to mitigate this have majorly been focused on dredging the Asa River channel which has not solved the problem. For an accurate spatial and temporal understanding of the risks of floods and their potential hazards, it is important to estimate floods using river hydrology. The objective of this study is to model steady flow of the rivers using flow data and to map flood-prone areas in Ilorin using HEC-RAS integrated with GIS. Using the HEC-GeoRAS extension in the GIS environment, the geometric data of the rivers were obtained from the 30 m resolution digital elevation model (DEM) and input into HEC-RAS applying Manning Co-efficient values of 0.04, 0.045, and 0.04. For each river, flow data (Q) was given as the upstream boundary condition while a normal depth of 0.001 was assigned for the downstream condition to model a steady flow and inundation extents. The result of the HEC-RAS model has shown the flood-prone areas along the river channels delineated. The floodplain map produced reveals the spatial distribution and extent of the high flood-risk areas in the Ilorin metropolis. The total flooded area covers approximately 60.95 km2 (18%) majorly along the river channels. This study has demonstrated that integration of hydraulic modelling using HEC-RAS and GIS process is capable of producing an inundation flood map with good accuracy that will aid in suggesting effective measures to mitigate the impact of flooding.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136359120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Jaqin, H. Kurnia, H. H. Purba, T. D. Molle, S. Aisyah
The mapping that has been done previously shows that there is a high processing time for the injection molding and shaft assembly processes in the S/A worm gear-type plastic industry. The purpose of this research is to identify and reduce waste in the injection molding process and the shaft assembly process to increase the amount of production. The research uses the lean concept approach method with the identification of causes carried out using the What-Why-Where-When-Who-How (5W+1H) method in focus group discussions (FGD) with competent parties in their fields. This study found that the type of waste obtained from the length of processing time (PT) from the injection molding section was 83.69% or 120.18 seconds and the shaft assembling section was 15.58% or 49.13 seconds, in total the processing time before improvement was 194.87 seconds. This research resulted in the injection molding processing time being reduced by 32.70% and the shaft assembly process by 37.82% with the change in processing time reduced by 26.40% so production results increased by an average of 103% per month.
{"title":"Lean concept to reduce waste of process time in the plastic injection industry in Indonesia","authors":"C. Jaqin, H. Kurnia, H. H. Purba, T. D. Molle, S. Aisyah","doi":"10.4314/njtd.v20i2.1396","DOIUrl":"https://doi.org/10.4314/njtd.v20i2.1396","url":null,"abstract":"The mapping that has been done previously shows that there is a high processing time for the injection molding and shaft assembly processes in the S/A worm gear-type plastic industry. The purpose of this research is to identify and reduce waste in the injection molding process and the shaft assembly process to increase the amount of production. The research uses the lean concept approach method with the identification of causes carried out using the What-Why-Where-When-Who-How (5W+1H) method in focus group discussions (FGD) with competent parties in their fields. This study found that the type of waste obtained from the length of processing time (PT) from the injection molding section was 83.69% or 120.18 seconds and the shaft assembling section was 15.58% or 49.13 seconds, in total the processing time before improvement was 194.87 seconds. This research resulted in the injection molding processing time being reduced by 32.70% and the shaft assembly process by 37.82% with the change in processing time reduced by 26.40% so production results increased by an average of 103% per month.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136358635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
These days, good quality road construction materials are scarce and their haulage to the construction site is expensive. When unsuitable materials are encountered during flexible pavement construction, the most technical and economical option is always to improve them to meet design standards. One of these deficient materials mostly encountered in tropical regions is kaolin clay soils. Cement and lime that are traditional deficient soil improvement agents are on high demand therefore have kept the cost of engineering construction financially high. Thus, the use of agricultural wastes such as sawdust and rice husk as alternative construction materials will considerably reduce the cost of construction and as well mitigate the environmental hazards caused by the wastes and cement production. This study investigated and compared the performance of rice husk ash (RHA) and sawdust ash (SDA) geopolymer cements in improving the geotechnical properties of kaolin clay soil used for flexible pavement construction. All laboratory experimental tests were carried out in accordance with British Standard (BS) 1377 and BS 1924 for natural and modified kaolin clay soil samples respectively. Soil samples were mixed with geopolymer cement at stepped concentrations of 0, 4, 8, 12, 16 and 20% by dry weight of soil. Results indicated that the plasticity index value of the natural kaolin clay of 18.52% was reduced to 7.24% at 20% RHA geopolymer cement content. The unconfined compressive strength of the natural soil was improved by 600 and 400 % by RHA and SDA geopolymer cements respectively. It was concluded that the use of up to 20% RHA and SDA geopolymer cements can efficiently and eco-friendly improve kaolin clay for flexible pavement foundation purpose.
{"title":"Enhancement of kaolin clay soil for civil engineering application using rice husk ash and sawdust ash geopolymer cements","authors":"A. Salahudeen, N. S. Kpardong, P. Francis","doi":"10.4314/njtd.v20i1.1232","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1232","url":null,"abstract":"These days, good quality road construction materials are scarce and their haulage to the construction site is expensive. When unsuitable materials are encountered during flexible pavement construction, the most technical and economical option is always to improve them to meet design standards. One of these deficient materials mostly encountered in tropical regions is kaolin clay soils. Cement and lime that are traditional deficient soil improvement agents are on high demand therefore have kept the cost of engineering construction financially high. Thus, the use of agricultural wastes such as sawdust and rice husk as alternative construction materials will considerably reduce the cost of construction and as well mitigate the environmental hazards caused by the wastes and cement production. This study investigated and compared the performance of rice husk ash (RHA) and sawdust ash (SDA) geopolymer cements in improving the geotechnical properties of kaolin clay soil used for flexible pavement construction. All laboratory experimental tests were carried out in accordance with British Standard (BS) 1377 and BS 1924 for natural and modified kaolin clay soil samples respectively. Soil samples were mixed with geopolymer cement at stepped concentrations of 0, 4, 8, 12, 16 and 20% by dry weight of soil. Results indicated that the plasticity index value of the natural kaolin clay of 18.52% was reduced to 7.24% at 20% RHA geopolymer cement content. The unconfined compressive strength of the natural soil was improved by 600 and 400 % by RHA and SDA geopolymer cements respectively. It was concluded that the use of up to 20% RHA and SDA geopolymer cements can efficiently and eco-friendly improve kaolin clay for flexible pavement foundation purpose.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42484665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In comparison to Europe, Asia, and America, the African manufacturing sector performs poorly. This is largely attributable in part to inadequate use of advanced manufacturing concepts and technologies, as well as the insufficiently skilled workforce. African manufacturing companies must adopt and implement advanced manufacturing technologies and concepts such as flexible manufacturing systems in order to boost growth and accelerate development in the sector. In this study, we conducted multi-case studies on the implementation of flexible manufacturing systems in the manufacturing sectors of two West African countries (The Gambia and Ghana). Six manufacturing companies from The Gambia and eight from Ghana were chosen. Many of the companies involved in the study are small businesses that specialize in mechanical parts/system production, welding, and fabrication. The findings revealed that the use of advanced manufacturing technologies and concepts, as well as the adoption of flexible manufacturing systems, is extremely low. The results also show that the major obstacles to the adoption and implementation of advanced manufacturing technologies are, cost and, lack of qualified personnel. Companies have agreed to adopt and implement advanced manufacturing technologies and concepts if the opportunity arises. They also require more information on some cutting-edge technologies before deciding whether to adopt and implement them. Some of the other major challenges faced by African manufacturing companies include, high energy costs and unstable power supply, poor transportation network, and, lack of adequate finance.
{"title":"Implementation of flexible manufacturing systems in Africa: Multiple case studies in the Gambia and Ghana","authors":"S. Fofana, F. Nyarko, L. Mensah, G. Takyi","doi":"10.4314/njtd.v20i1.1401","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1401","url":null,"abstract":"In comparison to Europe, Asia, and America, the African manufacturing sector performs poorly. This is largely attributable in part to inadequate use of advanced manufacturing concepts and technologies, as well as the insufficiently skilled workforce. African manufacturing companies must adopt and implement advanced manufacturing technologies and concepts such as flexible manufacturing systems in order to boost growth and accelerate development in the sector. In this study, we conducted multi-case studies on the implementation of flexible manufacturing systems in the manufacturing sectors of two West African countries (The Gambia and Ghana). Six manufacturing companies from The Gambia and eight from Ghana were chosen. Many of the companies involved in the study are small businesses that specialize in mechanical parts/system production, welding, and fabrication. The findings revealed that the use of advanced manufacturing technologies and concepts, as well as the adoption of flexible manufacturing systems, is extremely low. The results also show that the major obstacles to the adoption and implementation of advanced manufacturing technologies are, cost and, lack of qualified personnel. Companies have agreed to adopt and implement advanced manufacturing technologies and concepts if the opportunity arises. They also require more information on some cutting-edge technologies before deciding whether to adopt and implement them. Some of the other major challenges faced by African manufacturing companies include, high energy costs and unstable power supply, poor transportation network, and, lack of adequate finance.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47204886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Acid corrosion of steel and its associated financial and material costs are serious challenges to the chemical industry, and protecting these alloys through the use of effective corrosion inhibitors is imperative. In this study, the corrosion inhibition of mild steel in 1M HCl media using water and ethanol extracts of Spondias mombin leaves was investigated via weight loss technique, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The influence of temperature on inhibitor behaviour was also studied. Both extracts inhibited corrosion of mild steel via adsorption, following the Langmuir and Freundlich isotherms. The inhibition efficiency (IE) increased as extracts concentration was increased. After 24 and 72 hours exposure in the acid solution at 25 ℃, 500 ppm of extracts delivered maximum efficiency of (94.44 % and 76.52% for ethanol) and (51.52 % and 58,97 % for water). However, increasing temperature to 40 ℃ and 60 ℃ (after 24 hours) significantly boosted the efficiency of water extract (favoring inhibition via combined physical and chemical adsorption) but depreciated the performance of ethanol extract. The extracts provide good protection to mild steel in acidic environment and are therefore recommended as green alternatives to existing toxic ones.
{"title":"Inhibitory action of Spondias mombin leaves extracts on corrosion of mild steel in 1M HCl","authors":"K. Adama, B. Onyeachu","doi":"10.4314/njtd.v20i1.1294","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1294","url":null,"abstract":"Acid corrosion of steel and its associated financial and material costs are serious challenges to the chemical industry, and protecting these alloys through the use of effective corrosion inhibitors is imperative. In this study, the corrosion inhibition of mild steel in 1M HCl media using water and ethanol extracts of Spondias mombin leaves was investigated via weight loss technique, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The influence of temperature on inhibitor behaviour was also studied. Both extracts inhibited corrosion of mild steel via adsorption, following the Langmuir and Freundlich isotherms. The inhibition efficiency (IE) increased as extracts concentration was increased. After 24 and 72 hours exposure in the acid solution at 25 ℃, 500 ppm of extracts delivered maximum efficiency of (94.44 % and 76.52% for ethanol) and (51.52 % and 58,97 % for water). However, increasing temperature to 40 ℃ and 60 ℃ (after 24 hours) significantly boosted the efficiency of water extract (favoring inhibition via combined physical and chemical adsorption) but depreciated the performance of ethanol extract. The extracts provide good protection to mild steel in acidic environment and are therefore recommended as green alternatives to existing toxic ones.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48946752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the results of an investigation into the optimum depth of the lower concrete grade (LCG) at the tension region in a two-layer reinforced concrete beam. A total of nine (9) simply supported two-layer RC beams (1100 x100 x150 mm) were studied. Two 8 mm and two 6 mm diameter rods were used as reinforcement at the bottom and top of each two-layer beam, respectively. The beam samples were grouped into two: the first group comprises two-layer RC beams produced with 1:2:4 as the higher grade and 1:3:6 as the lower grade; the second group comprises two-layer RC beams cast with 1:2:4 as the higher grade and 1:4:8 as the lower grade. The depth of LCG adopted for each group is 25 mm to 100 mm at a step of 25 mm out of the total beam depth of 150 mm. The beams were subjected to two-point static loading to evaluate the load resistance and deflection. The results show that the greater the depth of the layer under compression, the stiffer the beam. The two-layer RC beam has an equal loading carrying capacity as the beam made entirely of higher grade. The depth of the layer of RC beam under tension in two-layer beams should be kept between 40 and 50% of the overall beam depth, which would be desirable structurally.
{"title":"Optimum depth of a lower concrete grade at the tension zone in a two-layer reinforced concrete beam","authors":"J. A. TrustGod, B. T. Blessing","doi":"10.4314/njtd.v20i1.1197","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1197","url":null,"abstract":"This paper presents the results of an investigation into the optimum depth of the lower concrete grade (LCG) at the tension region in a two-layer reinforced concrete beam. A total of nine (9) simply supported two-layer RC beams (1100 x100 x150 mm) were studied. Two 8 mm and two 6 mm diameter rods were used as reinforcement at the bottom and top of each two-layer beam, respectively. The beam samples were grouped into two: the first group comprises two-layer RC beams produced with 1:2:4 as the higher grade and 1:3:6 as the lower grade; the second group comprises two-layer RC beams cast with 1:2:4 as the higher grade and 1:4:8 as the lower grade. The depth of LCG adopted for each group is 25 mm to 100 mm at a step of 25 mm out of the total beam depth of 150 mm. The beams were subjected to two-point static loading to evaluate the load resistance and deflection. The results show that the greater the depth of the layer under compression, the stiffer the beam. The two-layer RC beam has an equal loading carrying capacity as the beam made entirely of higher grade. The depth of the layer of RC beam under tension in two-layer beams should be kept between 40 and 50% of the overall beam depth, which would be desirable structurally.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46658279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum was used as retarders. The aim of this study was to investigate the effect of retarders on consistency, setting time of ordinary Portland cement (OPC) paste and compressive strength of concrete cubes after 7 days of curing. OPC paste with a water cement ratio 0.4 to 0.5 was prepared by mixing 500 grams of ordinary Portland cement, a fixed amount of sugar of 0.02% by weight of cement with a combination of different gypsum of 1, 2, 3, 4, and 5% by weight cement and water. Sugar has a strong retarding effect, and this effect, controlled by Gypsum, can shorten the long setting time caused by sugar. The setting time of cement paste was reduced from 5.5 hours to 3 hours with an increase in Gypsum at a fixed amount of sugar. At a constant sugar content, increasing the gypsum content reduced the compressive strength from 31.5 MPa to 30.92 MPa.
{"title":"Effect of using sugar and gypsum as a retarder on concrete properties in Omani weather","authors":"K. W. Thanoon, S. A. Ali, S. Reddy","doi":"10.4314/njtd.v20i1.1264","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1264","url":null,"abstract":"This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum was used as retarders. The aim of this study was to investigate the effect of retarders on consistency, setting time of ordinary Portland cement (OPC) paste and compressive strength of concrete cubes after 7 days of curing. OPC paste with a water cement ratio 0.4 to 0.5 was prepared by mixing 500 grams of ordinary Portland cement, a fixed amount of sugar of 0.02% by weight of cement with a combination of different gypsum of 1, 2, 3, 4, and 5% by weight cement and water. Sugar has a strong retarding effect, and this effect, controlled by Gypsum, can shorten the long setting time caused by sugar. The setting time of cement paste was reduced from 5.5 hours to 3 hours with an increase in Gypsum at a fixed amount of sugar. At a constant sugar content, increasing the gypsum content reduced the compressive strength from 31.5 MPa to 30.92 MPa.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46366337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. A. Samuel, A. Sulaiman, H. A. Ajimotokan, S. E. Ibitoye, T. Ajiboye, T. Ogedengbe, I. O. Alabi
This study examined the morphology and microstructural evolution of resin-bonded palm kernel and coconut shell grain-based abrasive grinding wheels and their physico-mechanical and tribological properties. Raw palm kernel shell (PKS) and coconut shell (CNS) samples were obtained, sorted, sun- and oven-dried, pulverised, and screened into fines of 250, 500 and 850 μm grain sizes, and blended at PKS to CNS mixing ratios of 1:0, 0:1, 1:2, 1:1 and 2:1, respectively. The blended grains, on a weight basis of the total aggregates, were bonded with 25 wt.% polyester resin and hardened and catalysed with 1.5 wt.% cobalt compound and methyl-ethyl ketone peroxide. The aggregates were moulded and compressed at a constant pressure of 18 MPa, ejected, and room-cured before being oven-cured to produce the wheels. The microstructural, water absorption, impact, flexural, hardness, and wear rate properties of the produced samples were evaluated. The properties studied were significantly influenced by grain sizes and mixing ratios of the PKS and CNS in the wheels. The least hardness value, 6.42 HRB, and wear rate, 0.44 mg/m were found in wheels produced from aggregates with pure PKS content with 850 and 250 μm grain sizes, respectively. The wheels' durability qualities suggest they could be used as abrasive grinding wheels, in particular, for wood cutting and finishing processes.
{"title":"Morphology, microstructure evolution and properties of resin-bonded palm kernel and coconut shell grain-based abrasive grinding","authors":"A. A. Samuel, A. Sulaiman, H. A. Ajimotokan, S. E. Ibitoye, T. Ajiboye, T. Ogedengbe, I. O. Alabi","doi":"10.4314/njtd.v20i1.1235","DOIUrl":"https://doi.org/10.4314/njtd.v20i1.1235","url":null,"abstract":"This study examined the morphology and microstructural evolution of resin-bonded palm kernel and coconut shell grain-based abrasive grinding wheels and their physico-mechanical and tribological properties. Raw palm kernel shell (PKS) and coconut shell (CNS) samples were obtained, sorted, sun- and oven-dried, pulverised, and screened into fines of 250, 500 and 850 μm grain sizes, and blended at PKS to CNS mixing ratios of 1:0, 0:1, 1:2, 1:1 and 2:1, respectively. The blended grains, on a weight basis of the total aggregates, were bonded with 25 wt.% polyester resin and hardened and catalysed with 1.5 wt.% cobalt compound and methyl-ethyl ketone peroxide. The aggregates were moulded and compressed at a constant pressure of 18 MPa, ejected, and room-cured before being oven-cured to produce the wheels. The microstructural, water absorption, impact, flexural, hardness, and wear rate properties of the produced samples were evaluated. The properties studied were significantly influenced by grain sizes and mixing ratios of the PKS and CNS in the wheels. The least hardness value, 6.42 HRB, and wear rate, 0.44 mg/m were found in wheels produced from aggregates with pure PKS content with 850 and 250 μm grain sizes, respectively. The wheels' durability qualities suggest they could be used as abrasive grinding wheels, in particular, for wood cutting and finishing processes.","PeriodicalId":31273,"journal":{"name":"Nigerian Journal of Technological Development","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44248712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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