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 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 Pretreatment of recycle aggregates(2023) Olonade K.A.; Akindahunsi A.A.; Ajagbe W.O.; Adebanjo A.U.; Tijani M.A