Arid Zone Journal of Engineering, Technology and Environment (AZOJETE)
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Optimisation of Cover Thickness in Tyre Fibre Concrete under Elevated Temperature
Get PDFFailure of structural elements after fire outbreak is mostly attributed to spalling action. Spalling of concrete is an occurrence which results to decrease in the cross sectional area of the concrete elements, thus decreases the resistances to fire loads. This study, optimized the concrete cover thickness in tyre fibre concrete (TFC), which was subjected to single temperature load according to ISO 834 using graphical method. Three (3) samples were prepared from each series of mix containing tyre fibers of 10 mm width and varying length viz; 0%, 2.5%, 5.0% and 7.5%, using water cement ratio of 0.55. The samples were produced in 100 x 100 x 100mm cubes and tested for compressive strength. However, the cubes were structural modeled using TEDDS 2.0.01 and STAADPro v8i to under temperature load to determine optimum cover thickness through the deflection mode. The cover thickness for tyre-fibre concrete reduced from 25mm to 17.5mm under the same condition with the conventional concrete mixture. This shows that inclusion of tyre-fibre in concrete increases the fire resistance and reduces the cover thickness. It is recommended that tyre-fibre concrete should be used in our daily construction work for more durability
Mitigation of the Wear Failure of Ti-6al-4v Dental Implant Using Natural and Artificial Ageing Treatment
Get PDFTi-6Al-4V alloy has been in use as dental implants due to its favourable mechanical properties but wears off over a period of time in the oral cavity. Therefore, this research aimed at using natural and artificial ageing to mitigates the wear failure of Ti-6Al-4V dental biomedical implant. The as received Ti-6Al-4V alloy was sectioned under flowing cooling conditions to 1.4mm x 1.4mm x 0.3mm and then heat treated. The heat treatment involves solution heat treatment at 960oC for 1 hour followed by quenching in warm water at 60oC. After this stage, some of the samples undergo natural ageing for 24 hours, while others were further artificially aged to 480oC with varying soaking times of 2, 4, 6 and 8 hours followed by air cooling. Wear test was conducted at varying loads of 4N and 8N, linear speed of 13.12 cm/s and a dwell time of 30 minutes. The result showed that an increase in ageing time leads to a decrease in wear rate of the alloy for both loads. Also, the samples that were further artificially aged had more wear resistant than the naturally aged samples due to formation of precipitates which are homogenous with the matrix. The minimum wear rates of 0.0114 mm3/N/m and 0.0152 mm3/N/m was obtained at 4 and 8N loads respectively. Therefore, it was established that natural and artificial ageing combined can be employed to enhance the wear resistance of Ti-6Al-4V alloy for use in biomedical applications
Application of Microbial Induced Calcite Precipitation (MICP) Technology in Geotechnical and Geo-Environmental Engineering: A Review
Get PDFOne of the most recent areas of research in geotechnical and geo-environmental engineering is bio-mineralization, a natural process in living organisms, also known as Microbial Induced Calcite Precipitation. It is the formation of calcium carbonate from a supersaturated solution due to the presence of microbial cells and bio-chemical activities. In the process, microbes secrete metabolic products that reacts with ion in the medium to precipitate minerals. Through this process, soil improvement/remediation have been investigated and proven reliable with minute carbon print as compared to conventional binders. This paper presents an overview on the wide application of Microbial Induced Calcite Precipitation in the areas of geotechnical and geo-environmental engineering with the mechanisms and factors influencing its performance explained. The work has also considered both laboratory and field scale researches conducted in these areas. The key contribution of this work is the compilation of different approaches in soil stabilization and remediation, via urease producing microbes, in single source. It also outlined different treatment dosages based on environmental conditions suitable to soil types
Infiltration capacity of compacted lime treated black cotton soil as hydraulic barrier material
Get PDFStudies have shown the effect of hydraulic barriers in the reduction in movement of leachates, that have the potential of contaminating groundwater. Laboratory tests were conducted on black cotton soil treated with up to 5% lime by dry weight to assess its suitability in waste containment facilities. The test samples were subjected to particle size distribution analysis, consistency limit tests, compaction and hydraulic conductivity. The compaction energy of British Standard Light (BSL) was employed. The study showed decrease in liquid limit from 65.20% to 56.30% and plasticity index from 41.50% to 28.58% while plastic limit increased from 23.70% to 27.72% with the increase lime content. Maximum Dry Density (MDD) increases with increased in lime from 1.78 to 1.88 g/cm3 whereas the Optimum Moisture Content (OMC) decreased from 19.79% to 15.39%. Hydraulic conductivity of black cotton soil treated with percentage of lime content 0%, 1%, 3% and 5% of the soil weight examined for a period of 28days. The hydraulic conductivity value of natural soil was 1.65E-08 and decreased to 3.71 E-09 m/s at 5% lime content. Therefore, it is clear that hydraulic conductivity decreases with percentage increase in lime content. It is recommended that volumetric shrinkage, free swell and unconfined compressive strength should be carried out
Factors Affecting Time Performance of Tertiary Education Trust Fund Construction Projects in North-East, Nigeria
Get PDFHigher education institutions in Nigeria faced with the challenges of inadequate funding for the provision of facilities and rehabilitation of decaying ones. To address this issue, the Tertiary Education Trust Fund (TETfund) was established. However, it has been reported that, there are poor time performance of TETFund projects in tertiary institutions in Nigeria. This study was conducted to determine factors affecting time performance of Tertiary Education Trust Fund construction projects in north-east, Nigeria. Thirty-two (32) factors causing delay in construction projects were identified from the literature review. Data collection was carried out by means of survey questionnaire. One hundred and thirty-six questionnaires (136) were shared among construction professionals comprising of clients, contractors and consultants, 112 were returned completed representing 82% response rate. The data collected were analysed by means of frequency, severity index and Spearman’s rank correlation. The results obtained revealed that, the most common delay factor in TETFund construction projects according to the three categories of the respondents is late procurement of materials. Similarly, there is consensus among the three categories of the respondents that type of project bidding and award is one of the most severe delay factors in TETFund projects. Clients and consultants pointed out that, factors with high impacts on time performance include ineffective planning and scheduling of project by contractor, poor site management and supervision by contractor, and shortage of qualified workers. Whereas, based on contractors’ views, delay in progress payments by client has the highest impact. The study recommended that adequate planning and scheduling for all activities of project should be done by contractors at an appropriate time. The findings of this study can assist TETFund construction project team members to understanding factors that can significantly affect timely delivery of their projects
Modelling Self Purification of River Benue within Makurdi.
Get PDFThis study considered biochemical oxygen demand (BOD), dissolved oxygen (DO), the re- oxygenation rate, the de-oxygenation rate, the self-purification rate model for River Benue within Makurdi reach. The hydrodynamic data were collected while re-oxygenation rate, de-oxygenation rate and self purification rate were calculated using DO and BOD at 14 different stations along the river stretch. An empirical model for self purification was generated analytically using multiple linear regression equation analysis. The pH varied from 6.8 to 8.08 while DO concentration between 4.0 mg/L and 6.3 mg/L; BOD concentration ranges from 1.0 mg/L to 2.0 mg/L; Mean re-oxygenation rate of 0.179 in the raining season and 0.1 in the dry season; Mean de-oxygenation rate of 0.1186 day-1 in the raining season and 0.1345 day-1in the dry season was calculated; Self purification coefficient had a mean value of 1.3398 in dry season and 0.8354 in rainy season; The model has coefficient of determination (R2) and adjusted R2 of 0.5691 and 0.5469 respectively; a multiple correlation coefficient of 0.7544 and root mean squared error of 0.2433 between the observed field data and the model data. In conclusion, the river has good self purification ability and the model generated is reliable considering the root mean squared error
Characterization of Blends of Petrol and Bioethanol Synthesized from Nigerian Palm Bunch.
Get PDFThis study investigated fuel properties of pure petrol blended with bioethanol produced from Nigerian waste palm bunch. The produced bioethanol was blended with pure petrol at volume percentage ratio of 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40 and 100:0 to obtain E0, E10, E20, E30, E40, E50, E60 and E100 blend respectively. These were then characterized for fuel properties base on ASTM standard. The result confirmed that fuel properties of bioethanol produced from Nigerian waste palm bunch met the International Standard as established by ASTM for use in SI engine. The blends improved the fuel properties of pure petrol. Density of the blends increased as the percentage of bioethanol increases in the blends. Octane number of pure petrol increased with increase in bioethanol in the blends. Flash point of all the blends was below 15 oC making them susceptible to ignition and having the chance of flammability hazard. 10 % bioethanol increased the blend’s vapor pressure to a peak value of 53 kPa which declined with further increase of bioethanol percentage. The bioethanol increased viscosity of pure petrol. Calorific value of pure petrol was decreased with increase in the bioethanol content
Potentials of Utilizing Biodiesel from Cotton Seed Oil Blend with Diesel as an Alternative to Diesel Fuel in Nigeria
Get PDFThe depletion of fossil fuel reserves coupled with the environmental challenges pose by fossil fuel utilization make it necessary to search for better alternative fuels that have less adverse impact to the environment. Biodiesel and its blends as an alternative fuel in compression ignition (CI) engines are receiving more attention from researchers. This study investigates a blend of biodiesels from cottonseed oil and pure diesel prepared in percentage by volume in a proportion of 0:100, 10:90, 20:80 and 30:70 respectively. They were labeled as B0, B10, B20, and B30, and run on a single-cylinder, four stroke and water-cooled 165F diesel engine. The results show higher brake power for all blends when compared with pure diesel, with the lowest difference of 0.43% for B10 at a torque of 10 Nm and highest of 2.06% for B30 at 2 Nm torque. Specific fuel consumption (SFC) was also higher for the blends as compared to pure diesel, but the SFC is compensated with higher brake power. Pure diesel is observed to be thermally more efficient than biodiesel blends at low torque. The thermal efficiency difference ranges between 6.6–13.3% at 2 Nm. But at the torque of 10 Nm, the thermal efficiency of all blends is higher than pure diesel with about 3.3%. B30 shows better engine performance than pure diesel and the other two blends, but with slightly higher fuel consumption
Comparison of Multiple Linear and Quadratic Models in Estimating Road Crashes in Semi-Urban Two-Lane Roads: Case Study of Nsukka Municipal Council, South Eastern Nigeria
Get PDFRoad crashes are generally characterized by occurrence without prior notice as well as low or moderate to severe losses in terms of lives and properties. In particular, rural communities in developing countries count huge losses to crash exigencies due to lack of basic infrastructure. It is important that such accident trends which possess special and distinct features from those observed for Urban settlement be carefully studied and modeled for effective mitigation strategies. This paper proposes models that quantitatively assess the effects of various causal factors of crashes in rural roads of developing communities. Taking data from Nsukka municipality, South East Nigeria, it provides two reliable, statistically significant techniques of predicting accident rates on such roads. The results show that although important causal variables like “illiteracy, weather condition, alcohol and drugs” affect road accident, “reckless driving, over speeding, annual average daily traffic, poor road and mechanical faults” were variables that demand more assessment and control in road accident management in the studied location. Further, surface comparison of the developed models based on overall statistical indices suggests that multiple linear accident models are more accurate, though the quadratic accident model is statistically significant. A point by point calculation of deviations shows that the quadratic accident model, apart from its ability to take care of non-linearity effects of independent road accident variables, is actually more accurate than the linear model, except where the quadratic model suffered more numerical instability from the combination of numerical parameters
Performance Evaluation of Soiling Mitigation Technique for Solar Panels.
Get PDFSoiling is the accumulation of dust, leaves, and debris on the surface of photovoltaic modules which affects its overall conversion efficiency. Globally, several researches have indicated that with an increase in dust accumulation, the efficiency of the solar panels can drop by approximately 50%. This research aimed at increasing the efficiency of solar panels by mitigating the effects of soiling. The panel was incorporated with a dust sensor that senses increment in dust settlement and a DC Fan/blower which was placed in a position covering the surface of the panel. The speed of the installed fan can be varied using an L293D motor driver. It is actuated when the light intensity of the module falls below a set threshold. Solar energy parameters of the panel were measured and displayed on the constructed onboard controller. A comprehensive analysis was carried out on the design and the results show a 72% increase in efficiency after mitigation which reflects that controlled wind is an ideal technique in eliminating dust on solar panels