Civil Engineering
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Item Effect of Waste Polymer Modified Bitumen with Milled Corn Cob as a Partial Replacement for Filler in Asphaltic Concrete(2020) Ajagbe W.O.; Salami L.O.; Akinleye M.T.; Salami M.O.There is need to consider the use of cheaper and locally available materials so as to minimize the construction cost for sustainable development. Therefore, this research evaluated the physical and mechanical properties of waste plastic bottles modified bitumen with Milled Corn Cob (MCC) as a partial replacement for filler. Waste polymer was obtained from different waste generation points. A portable gas cooker was used to melt the waste polymer. Corn cob was sun-dried, and milled by an abrasion machine. Also, 60/70 penetration grade of bitumen was used for the study. The bitumen was replaced by waste polymer of 5%, 10%, and 15%. Bitumen modified samples were further prepared by mixing it with MCC of 10%, 30%, and 50%. Penetration, softening point, ductility, viscosity, flash point, fire point, loss on heating, specific gravity, stability, and flow were carried out on unmodified, modified bitumen and asphalt samples. All tests were conducted in accordance with the method of testing established by Indian Standard (IS) specification. Penetration, ductility, viscosity, flash point, fire point values decreases with increase in waste polymer content while softening point and loss on heating increases with increase in waste polymer content. Stability and flow value decreases with an increase in waste polymer and MCC content. The Optimum bitumen content, stability, and flow values for all the samples conform to the acceptable limits specified by Federal Ministry of Works (FMW) (1997) and IS specification. The results indicated an improvement in shear resistance, increment in resistance to deformation and optimum modifier content was found to be 10% for waste polymer and MCC.Item Compressive Strength of Concrete Using Sorghum Husk Ash and Calcium Chloride(2020) Tijani M.A.; Ajagbe W.O.; Ayininuola G.M.; Dahunsi B.I.O.; Agbde O.A.This paper investigated the effects of Sorghum Husk Ash (SHA) and Calcium Chloride (CaCl2) on the compressive strength of concrete. Concrete specimens were prepared by partial replacement of cement with SHA (5, 10, 15, 20 and 25% by weight) and addition of 1% CaCl2 by weight of binder; using a constant mix proportion (1:2:4) and water-to-binder ratio (0.6) for all mixtures. The properties evaluated were slump, density and compressive strength. The result indicated that addition of SHA reduced the slump (concrete turn out to be stiffer) and density of concrete. The 28 day compressive strengths result showed that 0%SHA/1%CaCl2 have the maximum strength of 28.11 N/mm2 followed by 5%SHA/1%CaCl2 (26.45 N/mm2), 10% (25.01 N/mm2), 0%SHA/0%CaCl2 (23.11 N/mm2), 15%SHA/1%CaCl2 (22.45 N/mm2), 20%SHA/1%CaCl2 (20.90 N/mm2) and 25%SHA/1%CaCl2 (18.13 N/mm2). This suggests that the best addition of SHA as fractional replacement for cement in CaCl2 concrete is in the range 0 - 20% since their compressive strength results were above 20 N/mm2 target strength. Incorporation of 1%CaCl2 together with 5 and 10%SHA would yield a concrete of greater compressive strength than standard concrete grade 20.Item Appropriate Simulation Technique for Complete Single-Bolt Shear Connection Shear-Out Tensile Properties and Fracture Behavior Predictions (2(2019) Adewole K.K.; Ajagbe W.O.This paper presents the finite element (FE) predictions of the complete S235, S690, Q550D, Q690D and Q890D steel grades steel sheet single-bolt shear connections shear-out (SBSCSO) behavior (tensile properties and fracture behavior). This work reveals that the FE elastic–plastic simulations without the damage and fracture model generally employed in the literature for SBSCSO failure predictions cannot predict the post-ultimate-load damage behavior, fracture initiation by elements removal and sudden drops in load required for determining the SBSCSO displacement at fracture. Consequently, the FE simulation without the damage and fracture model cannot accurately predict the complete SBSCSO tensile properties and fracture behavior. In particular, the FE simulation without the damage and fracture model cannot predict the SBSCSO displacement at fracture required for the seismic and fracture-resistant designs needed for the prevention of the failure of single-bolt shear connections that exhibit the shear-out fracture under extreme loading. FE simulation with the elastic, plastic damage and fracture models represents the appropriate simulation technique for the complete SBSCSO tensile properties and fracture behavior predictions.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 Impact of corroded bars and spalling on the bond strength of reinforced concrete structures(2020) Ajagbe W.O.; Ganiyu A.A.; Okoloekwe C.; Al-Alawi H.S.The mechanism of the composite materials in Reinforced Concrete Structure is such that they both have to undergo the same stress and deformation as the surrounding, so as to prevent discontinuity, slip, or separation of both materials .Bond strength results from a combination of several parameters, such as the mutual adhesion between the concrete and steel interfaces and the pressure of the hardened concrete against the steel bar or wire due to the drying shrinkage of the concrete. A total of 24 singly reinforced beams with plain 10mm and 12mm steel rods were cast for this study. The beams were designed to fail by flexure and to allow bond slips occur before ultimate failure. The spalling effect was simulated by debonding the bars along its entire length with PVC pipes thus restricting concrete and steel contact. The beams are then subjected to flexural test by inducing a point load on its mid span. The results of the investigation reveals a slight increase in the bond strength of about 2.68% with the use of already corroded bars and the bond strength decreased by 39.2% and 81.8% for bars that had 25% and 50% of their perimeters debonded. The increase in bond strength with the use of corroded bars can be ascribed to the increased frictional resistance owing to the corroded bars surface roughness. The loss of bond strength with decrease in contact area was as a result of the bar being unable to resist perpendicular stresses and was easily pushed out of the beamItem 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 structuresItem 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.Item Pretreatment of recycle aggregates(2023) Olonade K.A.; Akindahunsi A.A.; Ajagbe W.O.; Adebanjo A.U.; Tijani M.A