A REVIEW OF THE EFFECTS OF WASTEWATER ON REINFORCED CONCRETE STRUCTURES IN NIGERIA

This paper reviews the degradation mechanism of wastewater on reinforced concrete structures with a view to finding what needs to be done to salvage these structures. Potential disintegrating agents in wastewater generated in Nigeria were identified and common degradation effects were examined. Regeneration, preventive and corrective techniques were noted. While noting that poor maintenance culture, lack of multidisciplinary research work and high cost of maintenance were major factors responsible for the high rate of deterioration. The paper, therefore, concluded with suggestions that could be employed to salvage these structures from total collapse. One of such approaches is to use admixtures, which could reduce the effect of acidic attack common in wastewater concrete structures. http://dx.doi.org/10.4314/njt.v35i2.

Mechanical and Microstructural Characterization of Alkali-Activated Coconut Shell Ash Mortar

In this paper, potential of alkaline activation of coconut shell ash (CSA) as binder in mortar was investigated. Coconut shells were collected and calcined at temperature ranges between 500 and 900°C at interval of 100 for 30, 60 and 90 minutes to determine optimum burning condition that produces ash of higher silica content. Chemical composition of the ashes was then determined using X-ray Florescence (XRF) technique. Sodium hydroxide (NaOH) of different concentrations of 10, 12, 14 and 16 Molar (M) was used as alkaline activator, while mortar of mix ratio 1:3 was produced, while ratio of the alkali to CSA was of 0.5.  Mortar prisms of size 40 mm  40 mm  160 mm were cast and cured in an oven at a temperature of 80  for 7, 28, 56, 90 and 120 days. Thereafter, flexural and compressive strengths were determined at the end of each curing ages, following standard procedures. Scanning Electron micrographs of the hydrated mortar at 120 days were obtained using scanning electron microscopy (SEM) The results showed the oxide composition did not follow any pattern with increase in temperature but CSA produced at 800 for 1h gave the highest combined silica, alumina and ferric oxides above 70%, which is accepted as minimum value for pozzolanic materials.  Both compressive and flexural strengths of the activated mortar samples were found to increase with increase in activator concentration up to 14M and decline thereafter. At 120 days, the compressive strength was 13.9 N/mm2 while the flexural strength was 6.88 N/mm2. These values were higher than the strengths recommended by Nigerian Industrial Standard (NIS) for load bearing blocks. It was concluded that activation of CSA with NaOH could be used as binder for non-structural use. The SEM results indicated that mortar made from 14 M had structure that was densely packed compared to other mortar samples produced from other concentrations

Job Incentives And Career Knowledge As Predictors Of Workers Job Performance Among Employees Of Transmission Company Of Nigeria (TCN)

This study investigated job incentives and career knowledge as predictors of worker job performance in Transmission Company of Nigeria (TCN). The study was for the purpose of ascertaining whether job incentives significantly contributed to worker job performance among the workers in Transmission Company of Nigeria (TCN) or not.  In the study, primary data was used. Survey research design was used. Primary data was collected through self-administered structured questionnaire. Descriptive and inferential statistics were used to analyze the data. A total of 100 respondents from the organization were selected for the study using stratified Proportionate sampling technique. The researcher utilized three sets of questionnaire titled Job Incentives Scale, Workers Job Performance Scale and Career Knowledge Scale. Pearson’s Correlation was used to test the hypotheses. The findings of the study revealed that Job Incentives has weak negative relationship with job performance among worker of Transmission Company of Nigeria [r(96)= -0.11, p>0.05], also, findings revealed that career knowledge has weak positive relationship with job performance  among workers of Transmission Company of Nigeria [r(96)= 0.119, p>0.05]. It is recommended that employers should concentrate more on adequate job incentives and rewards to their workers to elicit positive attitude from them at work; and achieve job satisfaction which improves employee productivity and corporate performance. Keywords: Job Incentives, Career Knowledge, Workers, Job Performance. DOI: 10.7176/RHSS/9-14-15 Publication date:July 31st 201

Review of selected bio-wastes as potential materials for alkali-activation for cement-based products

There is growing need to finding alternative binder for Ordinary Portland Cement (OPC) as a result of the environmental hazards associated with its production. This paper presents the result of the review of selected bio-wastes as potential materials for alkali-activation in cement-based products. Studies carried out by several authors on the use of ashes from rice husk, cassava peel, sugarcane straw, corn cob and coconut shells were critically reviewed, while their chemical compositions as well as other criteria for alkali activation were identified. The review showed that the combined composition of SiO2, Al2O3 and Fe2O3 were in the ranges of 67.90 – 93.60, 46.59 – 72.25, 73.79 – 83.02, 41.13 – 78.30 and 71.3 – 77.57 % for rice husk ash, cassava peel ash, sugarcane straw ash, corn cob ash and coconut shell ash, respectively. These values met the requirement of ASTM 618 for materials to be considered as pozzolan, while the hydraulic coefficients of the ashes were also found comparable to notable industrial wastes that have been utilized for alkali-activation. It was also found that these materials are still not explored for alkali-activation. The paper concluded that the ash from these materials could be alkali activated to produce binders in cement-based products due to their potential properties.Keywords: Bio-wastes, alkali-activation, geopolymer, hydraulic activity coefficient, pozzola

A Study of Seepage through Oba Dam Using Finite Element Method

Dams are constructed to impound water for flood control, water supply, irrigation, energy generation, recreation as well as pollution control. Yet destructive effects of water on them are enormous. Seepage has been implicated as a major cause of dam failure due to its potential to cause internal eruption of soil. Different methods have been identified to study the extent of seepage in earth dams.  Of the methods, flow net is commonly used due to its relative simplicity. However, it becomes more complex with zoned earthfill dams.  In this paper, Finite Element Method (FEM) is employed to study seepage behaviour in Oba dam. Though the method was developed for the analysis of aircraft structural problems, due to its versatility, it is found as tool to solve variety of other practical problems. Finite Element formulation of the governing equation was established and computer programme was written to solve it. The bottom of the dam was meshed using rectangular element mesh while the piezometric heads at nodal points were determined. Also, determine was the coordinates that define the phreatic surface of the seepage. The results obtained were compared with those obtained from flow net approach which served as control using t-Test technique. It was observed that there was no significant difference (p > 0.0005) between the results. Thus, the method is appropriate for the study. The added advantage of the FEM is that simulation of the seepage problem of the dam becomes easy. Keywords: Finite Element, seepage, Oba dam, piezometric head, phreatic surface

Appraising capacity building among engineering students in selected universities in Southwestern Nigeria

A journal article on capacity building in Nigerian universities for Engineering students.This paper examined capacity building among engineering students in selected universities in south-western Nigeria. One hundred and fifty-one final year engineering students took part in the survey. A structured questionnaire were administered to the respondents as a tool for data collection. The data collected were subjected to descriptive and inferential statistical analysis using SPSS. The results showed that 66.9% of the respondents had passion for their choice of engineering courses. Out of 110 students that had access to computer system, about 87.4% had related engineering application software on their personal computer while only 76.2% could use them proficiently. Based on the students' responses, 93% of them expressed that their departments lacked adequate and state-of-the art equipment for practicals, 54% stated that practicals were carried out occasionally, while 95.6% indicated that Students Industrial Work Experience Scheme (S1WES) was very relevant to their study of engineering. The ANOVA conducted on the data showed that SIWES had significant effect on the understanding of their core courses (p<0.005). Also, the core values of the universities were significant to capacity building. The paper concluded that Nigerian universities had potentials to develop the needed human capacity in engineering but they can do better through provision of adequate equipment, strengthening the SIWES programme and laying more emphasis on vocational as well as entrepreneurial skills

Performance of Steel Slag as Fine Aggregate in Structural Concrete

Suitability of using steel slag (SS) as substitute for sand in concrete was investigated. SS was collected from a dump site, crushed manually and sieved through between sieves No. 4 and 200. SS was characterized using XRF and XRD techniques. Concrete of mix ratio 1:2:4 was batched by weight with slag replacement levels of 0 to 100% of sand at 25% interval and the concrete specimens (cubes and beams) produced were cured in water for 7, 14, 28 and 56 days. Water demand, compressive strength as well as flexural strength of the concrete were determined. Results indicated that SS contained high amorphous silica (42.40%) and ferric oxides (31.90%) with traces of crystalline particles. The water-cement ratio reduced from 0.62 to 0.50 as slag proportion increased from 0% to 100% at slump range of 6010 mm. The strength of SS concrete increased with increase in proportion of SS. The study suggested that up to 50% of weight of sand could be replaced with slag to produce structural concrete.http://dx.doi.org/10.4314/njt.v34i3.

Maternal mortality and maternal health care in Nigeria : implications for socio-economic development

Abstract: BACKGROUND: Even though maternal mortality, which is a pregnancy-related death is preventable, it has continued to increase in many nations of the world, especially in the African countries of the sub-Saharan regions caused by factors which include a low level of socioeconomic development. AIM: This paper focuses on cogent issues affecting maternal mortality by unpacking its precipitating factors and examining the maternal health care system in Nigeria. METHODS: Contemporary works of literature were reviewed, and the functionalist perspective served as a theoretical guide to examine the interrelated functions of several sectors of the society to the outcome of maternal mortality. RESULTS: It was noted that apart from the medical related causes (direct and indirect) of maternal mortality, certain socio-cultural and socioeconomic factors influence the outcome of pregnancy. Also, a poor health care system, which is a consequent of weak social structure, is a contributing factor. CONCLUSION: As a result, maternal mortality has debilitating effects on the socioeconomic development of any nation. It is therefore pertinent for the government to improve maternal health and eradicate poverty to ensure sustainable development

Comparative Analyses of Circularity Practices in Civil and Construction Engineering Between UK and Nigeria

The circular economy in the civil and construction engineering sectors is gaining momentum globally. The inadequate waste management system, especially in emerging nations, is quite concerning. Various waste sources such as construction and demolition (C&D), industrial wastes as well as agricultural wastes such as cassava peel, rice husk, and coconut fibre have been utilized in developing construction products. This study adopts the UK (United Kingdom) and Nigeria as two cases with critical analyses of the status quo and recommendations for promoting circularity. The existing studies on the circular use of waste construction products were comprehensively reviewed by mapping them against the Technology Readiness Level (TRL). The study addressed three research questions: (1) the existing locally available wastes used in civil and construction industries in the two studied countries, (2) the effects of these wastes on the properties of new construction products, and (3) visions to enhance circular use of wastes on civil and construction engineering practices. It is found that both countries have abundant industrial, agricultural, and demolition wastes that are potential materials for circularity in construction. While the TRL of utilizing these wastes is at an advanced stage in the UK, there is still a need for more concerted efforts to bring those wastes in Nigeria to a higher TRL. This study contributes to the existing body of knowledge by mapping the three aforementioned questions between the two studied countries, shedding light on continuous work in enhancing circular practices across the global civil and construction sectors