Civil Engineering
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Item Engineering and geological evaluation of rocks for Concrete production(2015) Agbede O.A.; Ajagbe W.O.Engineering and geological properties of rocks from eight different quarries in Ibadan were evaluated to determine their suitability for concrete production. Samples from each quarry sites were subjected to grading, relative density, water absorption, bulk density, amount of materials finer than 75μm, flakiness and elongation Index, Aggregate Impact Value (AIV), Aggregate Crushing Value (ACV), Aggregate Abrasion Value (AAV),10% fines value and petrographical analysis adopting BS testing methods. The relationship between engineering properties with one another and the petrographical characteristics were described by Pearson correlation coefficient and bar charts. The results of engineering analysis revealed that rocks from all the quarries are generally sound and good because of their possession of necessary characteristics for use in concrete production when compared with British (BS), Indian (IS) and American Society for Testing and Materials (ASTM) standards. Petrographical analyses revealed that samples which have performed better in all the engineering tests possess higher content of quartz mineral and finer texture. Statistically significant correlations were found among the tests performed.Item 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 flightItem 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.Item 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.OThe 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.Item Effect of crude oil impacted sand on the properties of concrete.(2012) Ajagbe W.O.; Agbede O.A.; Dahunsi B.I.OThis 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