Civil Engineering

The rise in economic, climatic changes, poverty, and hunger is directly proportional to the rising global population. With an estimated 7 billion people on earth, today and over 200 million in Nigeria alone, the spike in the stresses between food, water,

Cassava wastewater contains toxic materials that can endanger humans, as well as other living organisms if they are not properly treated before disposal. In order to address this problem, there is an urgent need to develop simple and efficient technologies for management of cassava wastewater, especially in tropical developing countries where cassava is extensively processed, and consumed on daily basis. This study was therefore, aimed at treating cassava wastewater by using alkali hydrolysis. Degradation products of cassava wastewater were characterized using different parameters under static and batch fermentation modes. With batch reactor as a model, hydrolysis of cassava wastewater over 20 days upon with wide range of NaOH concentrations was investigated. With 0.25 M NaOH, cyanide concentration was greatly hydrolyzed (44-fold) in 20 days. Furthermore, the alkali treatment drastically reduced the coliforms and reduced the biochemical oxygen demand in the cassava wastewater. This study apparently indicated that alkali treatment was very efficient in degrading the waste compounds from cassava. This system can be explored further for potential degradation of waste water treatment in tropical developing countries.

Cassava wastewater contains toxic materials that can endanger humans, as well as other living organisms if they are not properly treated before disposal. In order to address this problem, there is an urgent need to develop simple and efficient technologies for management of cassava wastewater, especially in tropical developing countries where cassava is extensively processed, and consumed on daily basis. This study was therefore, aimed at treating cassava wastewater by using alkali hydrolysis. Degradation products of cassava wastewater were characterized using different parameters under static and batch fermentation modes. With batch reactor as a model, hydrolysis of cassava wastewater over 20 days upon with wide range of NaOH concentrations was investigated. With 0.25 M NaOH, cyanide concentration was greatly hydrolyzed (44-fold) in 20 days. Furthermore, the alkali treatment drastically reduced the coliforms and reduced the biochemical oxygen demand in the cassava wastewater. This study apparently indicated that alkali treatment was very efficient in degrading the waste compounds from cassava. This system can be explored further for potential degradation of waste water treatment in tropical developing countries.

Heavy metal ions are often present in industrial wastewater, and sometimes there is the need to reduce their concentrations to some certain minimum. Biosorption is one of the methods by which this reduction can be achieved. The purpose of this study is to explore the biosorption technique as an alternative to conventional methods such as reverse osmosis, electro dialysis, ultra filtration, ion-exchange and chemical precipitation in the removal of heavy metal ions from industrial wastewater. Biosorption of the heavy metals namely cadmium, zinc and silicate were conducted using Pseudomonas Aeruginosa. Samples of wastewater from an industrial source were collected in a 2L container and poured into six containers. Measured quantities of the biomass were then introduced into the samples. The concentrations of heavy metals in the samples were determined with an atomic absorption spectrometer. The results yielded a significant reduction in the heavy metal ion concentrations in the samples, with even the highest initial concentration greatly reduced. Biosorption technique can be a very good alternative to conventional methods in terms of availability of materials, cost-effectiveness and absence of precipitates and slurry.

Physiochemical parameters of Onuimo River were studied so as to investigate its quality. Triplicate batches of samples were taken from three sampling points along the longitudinal stretch of the river and analyzed in the laboratory for physiochemical characteristics. The results were compared with both local and global standards for drinking water quality. Results showed that most of the parameters studied exceeded World Health Organization (WHO) and Nigerian Industrial standard (NIS) permissible limits for drinking water quality. Turbidity values ranged from 70NTU to 100.06 NTU, Total suspended solids ranged from 114.50mg/l to 128.1mg/l, Iron content ranged from 14.10mg/l to 38.05mg/l, dissolved oxygen ranged from 7.81mg/l to 13.41mg/l. This implies that the river is polluted and therefore unfit for drinking.

The aim of this study is to investigate the fresh and hardened properties of the self-compacting heavyweight concrete (SCHWC) and to develop a mathematical model for the prediction of these properties. The binder was the Portland cement and fly ash (FA). Barite aggregate was used to achieve the heavyweight concrete (HWC). A polycarboxylate based super plasticizer was used to increase workability and reach self-compacting feature. To research the fresh and hardened properties SCHWC many concrete mixes were prepared accordingly with "water-cement ratios", "total aggregate-cement ratios", and "fly ash-cement ratios". These samples were tested to get the slump-flow, V-funnel, 7 and 28-day compressive strength values. The Response Surface Methodology (RSM) was used to develop regression equations using these experimental results. It is observed that the estimated values obtained with RSM are compatible with those obtained by the experimental method for the fresh and hardened properties of SCHWC.

Traditionally, the choice of construction materials depended principally on the strengths of materials, cost of material, availability of materials, simplicity of erection, aesthetics and technical expertise available to the society. This meant that little attention was paid to the environment impacts of materials adopted for civil construction. After centuries of speedy advancement accompanied by deteriorating ecosystem as evidenced by the global climate change and the accompanying gap between the rich and the poor, the world is becoming more conscious of the ecosystem and the future of mankind. This has led to the growing quest for sustainable development. In the more recent years, environmental and sustainability factors are becoming compelling factors in the choice of construction materials. Researches focused on materials for affordable houses for the increasing low income masses are on the increase. This research focuses on the environmental impact performance of concrete and timber applied to a modest duplex residential building. It explores using Athena Impact Estimator software to model the greenhouses gases expressed in terms of carbon dioxide equivalents, sulphur dioxide equivalents, phosphate equivalents and ethane equivalents potentials obtainable from using concrete or timber to build a duplex residential building. From the various results obtained, it is very evident that timber construction is more eco-friendly in terms of carbon emission reduction which translates to reducing global warming, thermal insulation and energy efficiency. This will be helpful in making choice for building materials to be adopted for affordable houses developing countries.

Heavy metal ions are often present in industrial wastewater, and sometimes there is the need to reduce their concentrations to some certain minimum. Biosorption is one of the methods by which this reduction can be achieved. The purpose of this study is to explore the biosorption technique as an alternative to conventional methods such as reverse osmosis, electro dialysis, ultra filtration, ion-exchange and chemical precipitation in the removal of heavy metal ions from industrial wastewater. Biosorption of the heavy metals namely cadmium, zinc and silicate were conducted using Pseudomonas Aeruginosa. Samples of wastewater from an industrial source were collected in a 2L container and poured into six containers. Measured quantities of the biomass were then introduced into the samples. The concentrations of heavy metals in the samples were determined with an atomic absorption spectrometer. The results yielded a significant reduction in the heavy metal ion concentrations in the samples, with even the highest initial concentration greatly reduced. Biosorption technique can be a very good alternative to conventional methods in terms of availability of materials, cost-effectiveness and absence of precipitates and slurry.

Presence of cracks in concrete affect the integrity. It reduces the life expectancy of concrete structures and is often responsible for collapse of structures, especially in the developing nations. At the root of these cracks is the very low tensile strength of concrete. Various techniques have been suggested for the enhancing the tensile strength, among which is the use of discontinuous micro fibers of various nature. This research investigated the use of Momordica angustisepala (Ma) fiber to enhance concrete strength. Concrete containing coconut fiber was adopted as a control. Slump test, air entrainment test, compression test and split tensile test were carried out on specimens. Results of the research indicate that an optimum Momordica angustisepala fiber contents of 0.25 and 0.5% enhanced respectively the compressive strength by 4.37% and the tensile strength by 10%. The results clearly show that this renewable material has the potential to enhance the compressive and tensile strengths of concrete.

Various national and international standards recommend potable water for mixing concrete; however, the availability of potable water is virtually a daunting task in some developing communities. Concrete workers in such environments tend to utilize any available water for mixing concrete, and this may be detrimental to the quality of the concrete being produced. This study investigates the rheological, mineralogical and strength variability of concrete due to construction water impurities. Water samples were collected from four different construction sites within Southwestern region of Nigeria for production of concrete. The physical and chemical properties of the waters were determined so as to measure their rate of contamination, prior to their use for mixing concrete. The rheological properties of the fresh concrete, compressive strength, split tensile strength, and microscale features of hardened concrete, that were produced with each water sample were determined. From the result...

This study examined some geotechnical engineering properties of municipal solid waste contaminated soils in selected locations in Nigeria. Samples of soil were collected at 0.5m depth from the selected dumpsite, and a free land (uncontaminated soil) which served as control. The properties of the soils investigated include: particle size distribution, natural moisture content, consistency limits, maximum dry density, optimum moisture content and specific gravity. Test results revealed that the contaminated soils possess lower plastic limit, maximum dry density and specific gravity than the uncontaminated soil. However, the contaminated soil yielded higher natural moisture content, liquid limit, plasticity index, optimum moisture content and fine particles content than the uncontaminated soil. Therefore, within the limit of this study, it can be inferred that the geotechnical properties of the contaminated soil were reduced due to the influence of the municipal solid waste, and this m...

In order to determine the effects of coarse aggregate size on the flexural strength of concrete, concrete beams were produced in accordance with BS 1881-108 (1983) and American Society for Testing of Materials (ASTM C293) with varying aggregate sizes 9.0mm, 14mm, 18mm, and 24mm, using a standard mould of internal dimension of 150 x 150 x 750mm for the reinforced concrete beam. The water cement ratio was kept at 0.65 with a mix proportion of 1:2:4. The specimen produced were all subjected to curing in water for 28days and were all tested to determine the flexural strength using Universal Testing Machine. The slump tests (Workability) of the concrete mixtures prepared with each of the aggregate sizes were also conducted. The results showed that, aggregate sizes of 9.0, 14.0, 18.0 and 24.0mm have slump values of 101, 120, 158 and 160mm and flexural strengths of 4.91, 4.81, 4.13 and 4.03N/mm². It was concluded that, concrete to be used mostly to resist flexural stresses should be made of finer coarse aggregates.

Total potential energy was formed based on the traditional refined plate theory assumptions. Displacement field, kinematic relations, constitutive relations, stress displacement relations were derived from the deformed section of a thick anisotropic plate respectively. Strain energy was formed by substituting the kinematic relations and stressdisplacement relations into the universal strain energy equation. By the addition of the external work to the strain energy equation, total potential energy functional for analysis of thick anisotropic rectangular plate was obtained. The total potential energy functional were minimized by differentiating it with respect to the deflection, shear deformation rotation in x direction and shear deformation rotation in y direction respectively. This yielded the governing equation and two compatibility equations of thick anisotropic rectangular plate. A third order polynomial shear deformation function was derived from shear stress across the thickness of a rectangular plate section. The third order polynomial shear deformation function was employed to the governing equation and compatibility equation to obtain the displacement function (deflection, shear deformation rotation in x direction and shear deformation rotation in y direction). The general displacement functions obtained were used to satisfy the specified boundary conditions which gave the unique displacement functions for the various plate, (ssss), (cccc), (ccss), (cscs), (cccs), (csss), (ssfs), (ccfc), (csfs), (scfs), (scfc), (ccfs) respectivelyssss. Stiffness coefficients for various plate with their unique displacement functions were calculated. Minimizing total potential energy functional with respect to the coefficients of the displacement functions gave the formula for calculating the coefficients of the displacements and other formulas to calculate the displacements and stresses of the anisotropic thick plate. These formulas derived herein were used to analyze typical anisotropic rectangular thick plates. The numerical results obtained for displacements (w) were in good agreement with previous work by other scholars.

This research focuses on the use of accelerated curing of concrete by means of warm water at 35°C. The experiment was checked regularly to maintain same temperature all through thetime of heating.The workability and compressive strength properties of the concrete produced from mix ratio 1:2:4 have been ascertained. Compressive strength test on the hardened concrete at 7,14,21 and 28 days were as well obtained. From the results, the value obtained for the slump test corresponds to the design range of 25mm-100mm. The slump increased from 60mm in sample A to 65mm in samples B and C and then decreased to 50mm in samples D and E this can be associated with the variation in temperature as well as hydration. Furthermore, the hardened concrete was found to have lost some weight after curing, this is because weight loss is accompanied by strength gain. A relationship between the concrete cubes cured under 1day in the accelerated condition and normal concrete at 28 days was established so that the 28-day strength can be predicted from the accelerated. The relationship has been found mathematically as: R28 = Ra [0.8026 ± 0.0001]-1. Where R28 = 28-day strength andRa = accelerated strength. Optimal temperatures used in this research work is 35 ± 2°C. The 35°C used is optimal and help the hydration products, calcium silicate hydrates to settle suitably. Problem of possible compressive strength losses due to induced thermal stresses were taken care of by allowing a delay period equivalently equal to the initial setting time to elapse, so that concrete gained some tensile strength before curing commenced.

Dynamic analysis of frames involves very rigorous method which always requires software programming to take care of cumbersome calculations that are always involved. An easy manual method has been developed here to take care of these rigorous calculations that always require software programming. This method was used to analyze a three storey plane rectangular rigid frame. The condensed matrix gotten from this method was compared with that of Chopra and the result shows high similarity. Eigen value, eigenvector, shear force and base overturning moment of the three storey frame were also determined in the analysis. The results showed that plane rectangular rigid frames can easily be analyzed with this method which is less cumbersome and easy to apply. However this method cannot easily handle more than ten storey frames because of large matrix calculations involved.

This study was carried out by employing several observatory and analytical techniques to observe and understand the types and nature of cracks associated with building, the causes of such cracks, what could have been done to prevent these cracks as well as reparative measures that could be employed to remedy the cracks. Reconnaissance study was carried out on the structure to discover the nature and extent of cracks with the aid of traditional laboratory tools that can measures and monitor the cracks. From the overall properties and behaviours of the cracks, their possible causes and reparative measures could be established. The compressive structural strength of the key members of the building (slabs, columns and beams) was determined using the non-destructive Schmidt Hammer test. The minimum required compressive strength of 28day old concrete is 25 N/mm2, this is supposed to have attained a strength of 31 N/mm2 after 1year of the concrete life, and the strength is supposed to marginally increase with time. The shear strength of the foundation soil was determined through the shear box test which yielded the soil cohesion to be, c = 0.0355 kN/m² and angle of internal friction, = 25.34° = 25°. The ultimate bearing capacity of the foundation soil which is 409.86Kpa is satisfactory and was calculated using the Terzaghi's formula, Qu = cNc+γzNq+0.5BNγ. The majority of the cracks observed in the building are non-structural cracks. The main structural cracks observed in the building were caused by differential settlement of soil, faulty design and poor workmanship. Some of these are still actively cracking and hence pose a real threat of future collapse. Hence, they require urgent professional repairs. The appropriate remedy to cracks should be such that its nature and causes should be properly investigated and established before repair. Otherwise, wrongly treated cracks would reappear after some time