scholarly works

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Solid waste management in south western Nigeria
(2004) AGBEDE O.A.; AJAGBE W.O.
This study researches into solid waste management in South-West Nigeria in relation to pollution control using a an North as a case study. The generation pattern storage, collection and transportation, and the final disposal of solid waste ocean government are all discussed. Data used for this study were collected by the use of structured questionnaires and oral interviews. Analysis of the data revealed that all the functional elements of solid waste management system in the local government and the city of lbadan in general as practiced by existing institution - Ibadan Solid Waste Management Authority, are engulfed with fundamental problems which apparently have been the reason why institutions are unsuccessful in the efficient management of solid waste and control of environmental pollution. The various problems are identified, analyzed and discussed, pragmatic means of solving the problems, such as the encouragement of waste recycling; the active provision
Causes And Prevention Of Erosion In Urban Centres: A Case Of Okeotunu/Sanngo Area Of Ibadan City, Nigeria
(2004) Agbede O.A.; W. O. Ajagbe W.O
The causes of erosion in the study area, Okeitunu/ Sanngo, were investigated via the geology and soil properties of the area, the state of the existing road network and the drainage system, and the solid waste management practice in the local government area. It was revealed that both natural and man made activities contributed to the erosion of the area. Topographical nature of Okeitunu and the inadequate stream channel, in addition to bad environmental sanitation practices, unchecked vegetative removal and lack of enlightenment on the part of the inhabitants on erosion problems are the key factors causing the degradation of the Okeitunu environment. Stabilization of the steep slope, rehabilitation of the existing bare roads and damaged drainage will abate the wearing away of the soil. In addition, the populace needs to be enlightened to know what it takes to initiate or aggravate erosion.
Use of Efficient and Affordable Technologies in Checkmating the Existence of Hazardous Waste
(2010) Wahab A.A.; Issa F.O.; Dahiru B.; Ajagbe W.O.
One of the major problems impeding achieving environmentally sound management of hazardous waste (domestic, agricultural or industrial) in African countries is that there are no efficient and affordable technologies that can be adhered to. Human activities, either for production or processing lead to the production of wastes (solid, liquid or gas) which must be minimized because of their harmful effect on health of the living being and their destruction of environmental aestheticism. The technologies like rotary kiln, chemical disinfection etc, are efficient but they have not yielded the needed result. The reason is that they are not affordable. The affordable ones like brick or drum incinerator, waste burning and others result to massive emission of black smoke, fly ash and repulsive odours. All these eventually have negative effects on climate. This paper aims at promoting efficient and affordable technologies to manage hazardous waste in Ibadan, Nigeria. It provides information on the locations, types and sources of hazardous waste generated in this area and use this information to choose appropriate technologies that are affordable by the people. It is recommended that waste recycling and reuse, safe bury, waste minimization, composting and landfill technologies should be encouraged. Government at all levels should work in hand with the NGOs, community-based organizations, women, youth and public interest group programmes, in collaboration with local municipal authorities, to mobilize community support for waste reuse and recycling through focused community-level campaigns. Also, these technologies should be publicized through workshops, local meetings, and mass media to the populace for the benefit of the community and the country as a whole.
Environmental impact of rock blasting activities on adjoining structures and its inhabitants: A case study of landson quarry in Ibadn
(2011) Ajagbe W.O; Akanmu. O.M.
The impact of rock blasting activities on adjoining structures and on the health of the inhabitants was assessed by subjecting the inhabitants to administer structured questionnaire and response to simple questions concerning the state of their health. In addition, site reconnaissance survey, measurement of cracks on buildings and measurement of noise level were carried out. It was observed that the inhabitants are suffering from ailments traceable to the activities of the quarry in addition to general discomfort; the noise level being generated is approximately the same as the standard specified by the Federal Environmental Protection Agency. Also, it was discovered that the vibration generated from rock blasting is linked to some building collapse in the area while servicing ones are prone to collapse due to the high number of cracks on them. In conclusion, the sitting of quarry in residential area poses threats to both the structures and the people living in such area.
Faliure menance in engineering conference
(2011) Sule B.F.; Jimoh A.Y.; Adedeji A.A.
The collapse of building structures in recent time has become a source of worry for the professionals in the building industries with particular attention being on cement concrete structures. This paper however examined the causes and remedy to the ever increasing failure of mud buildings in cores of our major cities in Nigeria with particular focus on Ibadan South East Local Government Area of Ibadan, Oyo state. The major causes and nature of the failures of mud buildings, evaluation of the strength of failed buildings and the ones in service, and environmental impact of the collapsed buildings on the inhabitants were examined. Data used for this study were collected by the use of structured questionnaires, oral interviews, field trips made to selected areas to ascertain common failure of buildings and the use of Schmidt hammer to test the compressive strength of some selected mud buildings in the study areas. Secondary data were also obtained from local government officials and few published journals. It was observed that failure occur due to lack of adequate maintenance, improper alteration, poor planning of the area, vibrations from vehicles, poor drainage system, and poor solid waste management due to bad road network, material incompatibilities and primitive method of construction. Appropriate preventive measures were provided in the study as means of preventing future occurrence of the failures.
ANALYSIS OF TRAFFIC FLOW ON SELECTED TWO-LANE HIGHWAYS IN IBADAN METROPOLIS
(2011-09) AKINTAYO, F.O.
Traffic congestion is a common feature on highways in many cities of theworld, including Ibadan, Nigeria. Previous studies have shown that several mathematical traffic flow models developed to analyse congestion cannot be easily generalised or adapted to varying situations. In addition, validation errors of some models are as high as 60.0 %. In pursuit of the objective of minimising traffic congestion in parts of the Ibadan metropolis, headway simulation models were developed for the analysis of flow on some selected two-lane highways characterised by heavy traffic. Traffic survey was conducted on three purposively selected heavily-trafficked two-lane highways (Total Garden-Agodi Gate, J Allen-Oke Bola and Odo Ona-Apata) in the Ibadan metropolis. Headway modelling approach incorporating the prevailing mroadway, traffic and control conditions was developed. Field data were captured on the three roads with a camcorder between 7.00 a.m. and 6.00 p.m. for a period of six months as specified in the Highway Capacity Manual. Comparison of the modelling result and field headway data were carried out using Kolmogorov-Smirnov (KS) test (p = 0.05). A traffic flow simulator was developed to simulate the different congestion scenarios by varying the minimum and maximum headways. Capacity analysis and validation of the results were carried out using ANOVA methods. Average vehicular flow of 715 ± 3, 970 ± 5 and 1118 ± 9 vph per lane on Total Garden-Agodi Gate, J Allen-Oke Bola and Odo Ona-Apata roads respectively. Eighteen hyperbolic headway scenarios were produced and the highest coefficient of correlation (R2 = 0.92) was recorded at 90 percentile while 0.18, 0.36, 0.50, 0.71, 0.82, and 0.79 were obtained at 1, 10, 30, 50, 70, and 100 percentiles respectively. There was no significant difference between theoretical and field data using Kolmogorov- Smirnov (KS) test (p < 0.05). Also, a total number of 171 congestion scenarios were generated using the traffic flow simulator. Traffic flow varied between 204 and 2376 pcu per lane while headways varied between 1 and 18 seconds. The capacity analysis produced approximated maximum flow rates of 1850, 2865 and 2881 pcu in the two directions of travel for Total Garden-Agodi Gate, J Allen-Oke Bola and Odo Ona- Apata roads respectively. The capacity of Total Garden-Agodi Gate was within the recommended maximum value of 2800 pcu in the two directions of travel for two-lane highways. The results for J Allen-Oke Bola and Odo Ona-Apata roads showed that an additional lane will be required in each direction of travel. The validation of the models on the dualised J Allen-Oke Bola road showed that congestion can be reduced by about 55.0 %. A maximum validation error of 35.0 % was obtained. The traffic flow simulator developed successfully simulated the traffic situations on the selected highways. The analysis of the flow yielded results that could ameliorate traffic congestion on the selected two-lane highways in the Ibadan metropolis.
Effect of crude oil impacted sand on the properties of concrete.
(2012) Ajagbe W.O.; Agbede O.A.; Dahunsi B.I.O
This study investigates the effect of Crude Oil Impacted Sand (COIS) on some engineering properties of fresh and hardened concrete. Total Petroleum Hydrocarbon (TPH) test was carried out on samples from the study area to determine the level of crude oil contamination. Based on the test results, six levels (2.5%, 5%, 10%, 15%, 20% and 25%) of artificial contaminated sand were prepared and engineering properties including slump, compacting-factor, flow-table, compressive-strength, flexural-strength, water-absorption, linear-shrinkage, surface-resistivity, and fire resistance were determined using standard methods. Predictive models were developed and concrete mixes were designed using COIS for reinforced concrete stuctures. TPH of the soil samples varied from 8.6 to 14.1%. The slump, compacting factor, flow-table, and surface-resistivity of the COIS concrete increased with levels of contamination. Compressive-strength, flexural-strength, shrinkage, water absorption and fire-resistance of the COIS concrete reduced with increased level of contamination. Coefficient of determination, R2, of the models ranged from 0.823 to 0.998. Mix ratio of 1: 1.6 : 2.4 of cement : COIS: coarse aggregate was found to be appropriate at 0.45 w/c. The Crude Oil Impacted Sand concrete with not more than 10% contamination is suitable for use in low strength structures
Use of the Beam Analogy Approach to Predict the Ultimate Shear Strength of Prestressed Flat Slab
(2012) AGBEDE O.A.; AJAGBE W.O.
The aim of the study was to predict the ultimate shear strength of a prestressed flat slab at the slab-column junction using the beam analogy approach. The beam analogy method, with other shear strength prediction methods such as the methods proposed by Hawkins, ACI 318-02, CSA A23.3-2004 were studied. The results were compared with the BS Code results to determine the variation in shear strength values. The approach employed a hypothetical flat slab layout, which was analyzed and designed for shear using all the various approaches while considering centre, edge and corner conditions. Values of the shear capacity were obtained using spreadsheet by varying the depth of the slab, and the area of the column. The values of the shear capacity of all the four methods were compared with the BS 8110. The results showed that there was a close relationship between the beam analogy approach and the BS 8110 method of shear strength prediction. As the depth of the slab increased, the beam analogy method was found to be more conservative, and as expected, the concrete shear stress at the slabcolumn junction reduced with increase in slab depth, which is the same depth for the idealized beam. Also, as the column area increased, while other parameters held constant, the shear strength at the junction was fortified. Also increasing the column area gave a closer relationship between the beam analogy approach and the BS Code than increasing the slab depth.
Reliability Assessment of Bridge Decks: A Case Study of Three Bridges Along Lagos – Ibadan Expressway.
(2012) AGBEDE O.A.; AJAGBE W.O
The ageing and gradual deterioration of bridges in Nigeria needs balancing of cost-effective plans for bridge maintenance, rehabilitation and replacement. This research aims at assessing the reliability of bridges using three existing highway bridges along Lagos-Ibadan expressway as a case study. Visual inspection, sounding, half-cell potential and chloride concentration tests were utilized to evaluate the conditions of the bridges. Deteriorations were observed on the decks’ surfaces. The level of corrosion on one deck was active and uncertain in the remaining two. The chloride concentrations on all the decks were within AASHTO standards and only one of the decks had delaminated. The results revealed that none of the decks needs total replacement but all require some form of rehabilitation.
Construction and building materials
(2012) AGBEDE O.A.; AJAGBE W.O.
This study researches into solid waste management in South-West Nigeria in relation to pollution control using a an North as a case study. The generation pattern storage, collection and transportation, and the final disposal of solid waste ocean government are all discussed. Data used for this study were collected by the use of structured questionnaires and oral interviews. Analysis of the data revealed that all the functional elements of solid waste management system in the local government and the city of lbadan in general as practiced by existing institution - Ibadan Solid Waste Management Authority, are engulfed with fundamental problems which apparently have been the reason why institutions are unsuccessful in the efficient management of solid waste and control of environmental pollution. The various problems are identified, analyzed and discussed, pragmatic means of solving the problems, such as the encouragement of waste recycling; the active provision
Comparative Study on the Design of Elevated Rectangular and Circular Concrete Water Tanks
(2012) AGBEDE O.A.; AJAGBE W.O.
Reinforced concrete overhead water tanks are used to store and supply safe drinking water. Design and cost estimation of overhead water tanks is a time consuming task, which requires a great deal of expertise. This study therefore examines the efficiency of Rectangular and Circular tanks. Tanks of 30m3, 90m3, 140m3 and 170m3 capacities were used in order to draw reasonable inferences on tank’s shape design effectiveness, relative cost implications of tank types and structural capacities. Limit state design criteria were used to generate Microsoft Excel Spreadsheet Design Program, named MESDePro for quick and reliable design. The basic tank’s construction materials- steel reinforcement, concrete and formwork were taken-off from the prepared structural drawings. Results of the material take-offs showed that, for each of the shapes, the amount of each structural materials increase as the tank capacity increases. Also Circular-shaped tank consumed lesser individual material as compared to Rectangular ones. Hence, this will give Circular-shaped tanks a more favoured selection over the rectangular shaped tanks.
ANALYSIS OF PRE-CAST WAFFLE SLABS USING YIELD LINE AND RANKINE GRASHOFF THEORIES
(2012-09) AKINYELE, J. O.
Failure in pre-cast waffle slabs can be attributed to factors like analytical error, poor handling during transportation and placement which factors often lead to partial/total failure of slabs. The conventional method of analysing waffle slabs focuses on the ribs, while the slab portions at the top are avoided. This has led to under reinforcement and subsequent failure of the slab portions that are usually in direct contact with loads. In this study, a method that incorporates both the slab and rib portions in the analysis of pre-cast waffle slabs was therefore developed. Yield Line and Rankine Grashoff Theories (YLRGT) were combined for the analysis of pre-cast waffle slab. Six physical models of waffle slab were developed, each having five replicates, with the following dimensions: W1 (1353 x 430 x 58 mm), W2 (900 x 300 x 50 mm), W3 (1085 x 430 x 58 mm), W4 (407 x 364 x 50 mm), W5 (1312 x 300 x 58 mm) and W6 (860 x 360 x 50mm). Solid slabs of the same size and number designated S1, S2, S3, S4, S5 and S6 served as control. These models were validated using the slabs by testing for failure loads, deflections and crack width. Each slab was subjected to incremental load of 1.0 kN until failure occurred. Maximum bending moments were obtained for slab and rib portions using YLRGT, a finite element based method called ETABS was also used to analyse the slabs and results obtained were subjected to statistical analysis using ANOVA at p= 0.05. The YLRGT analysis of the various physical models (slab portion, transverse and longitudinal ribs) yielded the following bending moments: W1 (5526.0, 34.5, 918.3) Nm, W2 (1122.0, 279.2, 36.5) Nm, W3 (2880.0, 27.2, 619.9) Nm, W4 (590.0, 171.9, 160.9) Nm, W5 (947.0, 37.0, 4.4) Nm and W6 (1276.0, 90.4, 36.2) Nm respectively. The ETABS combined both slab and ribs giving W1 (4729.0) Nm, W2 (581.0) Nm, W3 (3338.0) Nm, W4 (733.0) Nm, W5 (851.0) Nm and W6 (686.0) Nm. Deflections at failure for waffle slab were smaller compared to solid slabs: (W1 = 1.19 and S1 =3.56) mm, (W2 = 3.64 and S2 =9.28) mm, (W3 = 3.90 and S3 =7.44) mm, (W5 = 8.17 and S5 =12.18) mm, (W6 = 3.29 and S6 =3.89) mm with the exception of W4 (6.60 mm) and S4 (6.44mm), where deflection of waffle slab was higher than that of solid slab. Mean deflection of S1 was significantly higher than W1, while S2 was significantly higher than W2. Average crack width for waffle (0.48 mm) and solid slabs (0.99 mm) were significantly different. High crack width in solid slab indicated lower shear strength. The Yield Line and Rankine Grashoff Theories have facilitated the accurate analysis of pre-cast waffle slabs by separating the slab and rib portions.
ANALYSIS OF PRE-CAST WAFFLE SLABS USING YIELD LINE AND RANKINE GASHOFF THEORIES
(2012-09) AKINYELE, J.o
Failure in pre-cast waffle slabs can be attributed to factors like analytical error, poor handling during transportation and placement which factors often lead to partial/total failure of slabs. The conventional method of analyzing waffle slabs focuses on the ribs, while the slab portions at the top are avoided. This has led to under reinforcement and subsequent failure of the slab portions that are usually in direct contact with loads. In this study, a method that incorporates both the slab and rib portions in the analysis of pre-cast waffle slabs was therefore developed. Yield Line and Rankine Grashoff Theories (YLRGT) were combined for the analysis of pre-cast waffle slab. Six physical models of waffle slab were developed, each having five replicates, with the following dimensions: W1 (1353 x 430 x 58 mm), W2 (900 x 300 x 50 mm), W3 (1085 x 430 x 58 mm), W4 (407 x 364 x 50 mm), W5 (1312 x 300 x 58 mm) and W6 (860 x 360 x 50mm). Solid slabs of the same size and number designated S1, S2, S3, S4, S5 and S6 served as control. These models were validated using the slabs by testing for failure loads, deflections and crack width. Each slab was subjected to incremental load of 1.0 kN until failure occurred. Maximum bending moments were obtained for slab and rib portions using YLRGT, a finite element based method called ETABS was also used to analyse the slabs and results obtained were subjected to statistical analysis using ANOVA at p= 0.05. The YLRGT analysis of the various physical models (slab portion, transverse and longitudinal ribs) yielded the following bending moments: W1 (5526.0, 34.5, 918.3) Nm, W2 (1122.0, 279.2, 36.5) Nm, W3 (2880.0, 27.2, 619.9) Nm, W4 (590.0, 171.9, 160.9) Nm, W5 (947.0, 37.0, 4.4) Nm and W6 (1276.0, 90.4, 36.2) Nm respectively. The ETABS combined both slab and ribs giving W1 (4729.0) Nm, W2 (581.0) Nm, W3 (3338.0) Nm, W4 (733.0) Nm, W5 (851.0) Nm and W6 (686.0) Nm. Deflections at failure for waffle slab were smaller compared to solid slabs: (W1 = 1.19 and S1 =3.56) mm, (W2 = 3.64 and S2 =9.28) mm, (W3 = 3.90 and S3 =7.44) mm, (W5 = 8.17 and S5 =12.18) mm, (W6 = 3.29 and S6 =3.89) mm with the exception of W4 (6.60 mm) and S4 (6.44mm), where deflection of waffle slab was higher than that of solid slab. Mean deflection of S1 was significantly higher than W1, while S2 was significantly higher than W2. Average crack width for waffle (0.48 mm) and solid slabs (0.99 mm) were significantly different. High crack width in solid slab indicated lower shear strength. The Yield Line and Rankine Grashoff Theories have facilitated the accurate analysis of pre-cast waffle slabs by separating the slab and rib portions.
Environmental Impact of Road Dualisation: A Case Study of Mokola-Ojoo Road in Ibadan
(2013) AGBEDE O.A; AJAGBE W.O
The impacts of the dualisation of Mokola - Ojoo road in Ibadan, Nigeria on the inhabitants, socio-economic activities, biological and air environment were studied using physical observation and questionnaire survey. The dualisation caused the demolition of some adjoining structures and historic site, displacement of the inhabitants, the pollution of air with dust and carbon monoxide and brought untold hardships on the road users. Although the long term benefit of the dualisation is well recognized, the negative impacts may as well reduce the benefit thus establishing the importance of conducting proper Environmental Impact Assessment prior to the commencement of the project.
Quality Assessment of Sandcrete Blocks in Ibadan – A review
(2013) AGBEDE O.A.; AJAGBE W.O.
Sandcrete blocks have been widely used for modern building construction in Nigeria; however cases of incessant building collapse are rampant. The usage of substandard sandcrete blocks is a contributing factor. This research was carried out to assess the engineering properties of sandcrete blocks produced in Ibadan and its environs. Two blocks each of size 450 x 225 x 225mm were purchased from selected block industries at eight sampled locations within the study area. Few units of blocks (450 x 225 x 225mm) conforming to the Nigerian Industrial Standard (NIS 87:2007) were also produced to serve as control samples. The 28th day dry compressive strength test result obtained for the sampled blocks ranges between 0.39-2.34N/mm2. For the control block samples, the average 28th day dry compressive strength of the three tested blocks was 3.02N/mm2. Conclusively, it was observed that the sandcrete blocks produced in major parts of Ibadan were of low quality and substandard; while the control samples were of adequate strength.
Modeling the Effect of Crude Oil Impacted Sand on the Properties of Concrete Using Artificial Neural Networks
(2013) AGBEDE O.A.; AJAGBE W.O.
EFFECT OF CRUDE OIL CONTAMINATED SAND ON THE ENGINEERING PROPERTIES OF CONCRETE
(2013-01) AJAGBE, W. O.
A considerable fraction of sand in Niger Delta Area of Nigeria is contaminated with crude oil. The contaminated sand is largely utilised by local contractors for the production of concrete. However, there is need to establish its suitability in concreting. Previous works have centered on hardened uncontaminated concrete in crude oil environment but not on concrete made with Crude Oil Contaminated Sand (COCS). This research was designed to evaluate the effect of COCS on some engineering properties of fresh and hardened COCS concrete. Levels of crude oil contamination were determined using gravimetry method of Total Petroleum Hydrocarbon (TPH) test on nine sand samples randomly collected from some oil spill sites in Rivers State. Based on the test results, seven types of artificially contaminated sand were prepared with crude oil levels of 0.0, 2.5, 5.0, 10.0, 15.0, 20.0 and 25.0%. Workability (slump, compacting factor and flow), compressive strength, linear shrinkage, water absorption, and fire resistance were determined using concrete cubes, flexural strength using concrete beams, and surface resistivity using concrete cylinders in accordance with standard methods. Data obtained were analysed using ANOVA at p = 0.05. Eight models were developed using historic response surface methodology to predict the engineering properties of COCS concrete at water-cement ratio (w/c) of 0.5. Also, COCS concrete design mixes with contamination level and w/c ratio suitable for reinforced concrete were formulated. The TPH varied from 8.6 ± 0.2 to 14.1 ± 1.3%. The workability of concrete was improved by the presence of COCS. Slump, compacting factor and flow of the fresh concrete increased with increase in contamination from 30.0 to 200.0 mm, 0.5 to 0.9 and 15.0 to 85.0%, respectively. Compressive strength, flexural strength, linear shrinkage and water absorption of the hardened concrete reduced with levels of contamination from 31.5 ± 2.3 to 3.5 ± 0.0 N/mm2, 5.9 ± 0.8 to 0.1 ± 0.0 N/mm2, 0.1 ± 0.0 to 0.0 cm and 0.2 to 0.0 kg respectively. At a temperature of 200.0˚C, the percentage strength reduction increased from 18.4 to 94.8% for 2.5 to 25.0% contamination. Surface resistivity ranged from 25.1 ± 0.2 to 32.3 ± 0.2 kΩ-cm. The compressive and flexural strengths of COCS concrete were reduced by more than 50.0% at crude oil contamination level greater than 10.0%. The water absorption and surface resistivity values indicated that COCS concrete exhibited greater resistance to water and chloride penetration respectively, it shrank less when compared with the uncontaminated concrete, but exhibited poor fire resistance. Coefficient of determination, R2, of the models developed ranged from 0.823 to 0.999. Concrete design mix ratio of 1part of cement to1.6 part of COCS (10.0% crude oil) to 2.4 part of coarse aggregate was found to be appropriate at 0.45 w/c. This mix gave minimum compressive strength of 21.0 N/mm2 which is acceptable for reinforced concrete structures. Concretes produced with sand contaminated with less than ten percent crude oil were found suitable for use in low strength structures. Mix re-design using lower w/c improved the strength of the concrete.
Finite element analysis of a free-standing staircase
(2014) Agbede O.A.; Ajagbe W.O.
The existing approximate analytical methods of analyzing free-standing stairs fail to predict the distribution of any stress resultan t an d the actual three dimensional behavior of the atair slab system. A more rationale but simple and accurate method of analysis based on ffnite element method is presented. Plate flexural analysis is used to evaluate unknown displacements at each node of a rectangular plate element. Spreadsheet (FEM 2D) i also used to onalyze the stairs and to compare the finite element analysis with the analytical method. The study reveals that the variation of stress resultants across a aection is non-uniform, which is otherwise not recognized by the analytical methods. This indicates that the effects ot axial forces in flights are more than offset by the effect ot in-plane moment which causes lateral sway of the whole stair towards te upper flight
Effect of the portland-limestone cement grades on the compressive strength of hollow sandcrete blocks
(2014) Agbede O.A.; Ajagbe W.O.
The commercial sandcrete block makers in Nigeria use the same cement-sand mix ratio for sandcrete blocks production irrespective of the cement grade. Investigation revealed that the compressive strengths of hollow sandcrete blocks produced with Portland-limestone cement grade 42.5 are higher than the sandcrete blocks produced with cement grade 32.5. The use of stronger sandcrete blocks produced with cement grade 42.5 will ensure the construction of stronger buildings and other sandcrete blocks-based infrastructures and reduce the incessant failure of building and other sandcrete blocks-based infrastructures in Nigeria at no additional cost as both cement grades cost the same amount in Nigeria. It is recommended that the Standards Organisation of Nigeria should create grassroots awareness on the different cement grades in Nigeria and specify that Portland-limestone cement grade 42.5 be used for sandcrete blocks production.
EFFECTS OF LEAD LEVELS ON INDOOR AND BUILT OYO STATE NIGERIA ENVIRONMENT IN IBADAN
(2014-08) ADEBAMOWO, E. O.
Environmental exposure to lead, a highly toxic heavy metal, is a significant cause of human morbidity and mortality. However, the determination of lead levels in homes and built environment have not been well investigated in Nigeria. This study was designed to evaluate the lead levels in dust, paint, paint chips, soil and water; and to ascertain the geotechnical properties of soil in the home environment in Ibadan. Four Focus Group Discussions (FGDs) were conducted and six hundred questionnaires randomly administered to evaluate knowledge about lead exposure in Ibadan. Responses were compared using Wilcoxon rank-sum tests for continuous variables and χ2 for categorical variables at p = 0.05. Lead levels in paint from twenty-five samples obtained from five manufacturers were measured. Three-hundred samples from urban areas were taken randomly from dust from door step of the house entrances and window sills, paint chips from walls, soil at 2000mm from fence wall and 300mm depth from front and back of the houses and portable water from taps and their lead levels measured. Atomic Absorption Spectroscopy was used to determine the lead levels in these samples. Geotechnical engineering tests were carried out to determine the Maximum Dry Density (MDD), Optimum Moisture Content (OMC), Liquid Limit (LL), Plastic Limit (PL), and California Bearing Ratio (CBR) of the sampled soil. Most respondents (86%) from the FGDs and the questionnaires (86%) had no knowledge about lead exposure in home environment. Twenty-four (96%) from the twenty-five paint samples exceeded the recommended lead level in paint of 90 ppm. Yellow paint had the highest lead level of 50,000 ppm; indicating high risk and white paint had the lowest lead level of 84 ppm. Dust lead levels from door steps of house entrances have average of 115.1 ± 1 12.9 ppm and dust lead levels from window sills have average of 83.3 ± 13.3 ppm; due to lack of proper regular cleaning. Paint chips lead levels from walls have average of 2,894.6 ± 79.5 ppm; due to flaking old paint that emits lead. Soil lead levels in front of houses have average of 135.3 ± 4.5 ppm and soil lead levels from back of the houses have average of 69.4 ± 5.9 ppm; due to lack of landscaping to cover exposed soil surfaces. Potable water lead levels have average of 0.21 ± 0.02 ppm, against recommended value of 0.01 ppm due to usage of lead water pipes. The values of the geotechnical parameters obtained ranged from 1.8 – 2.0 g/cm3 (MDD), 8.5 - 13.8% (OMC), 17.8 – 29.6% (LL), 14.2 – 23.4% (PL), and 59 - 95% (CBR); all within normal recommended values. The indoor and built environments in Ibadan are highly affected by high lead levels. Lead levels in paint used in homes should be reduced to minimize human morbidity and mortality. The usage of non-lead water pipes is highly recommended. Lead levels in soil in the home environment do not affect the geotechnical characteristics of soil.