FACULTY OF TECHNOLOGY
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Item Repair and strengthening of bamboo reinforced acrylic polymer modified square concrete columns using ferrocement jackets(2020) Akinyemi B.A; Omoniyi T.EThis study investigated the role of acrylic polymer as concrete matrix modifier and fer- rocement jacket confinement to repair and strengthen treated bamboo reinforced square concrete columns. 30 concrete columns (CC) of 150 ×150 ×600mm were produced us- ing cement:sand:aggregate ratio of 1:3:3 and a polymer:cement ratio of 1:10 based on ACI 548.3R standard. 10 CCs’ were produced from both conventional and modified concrete which were tested until failure. Another 10 CCs’ from both concrete design mixes were preloaded at 25%, 50%, and 75% of ultimate load and thereafter repaired with ferrocement jacket and axially tested. The last 10 CCs’ were ferrocement jacketed before axial testing. Axial and lateral deflections were evaluated during the tests. The crack pattern and fail- ure modes of the columns were also considered. The highest average ultimate load was obtained from column with ferrocement and polymer addition at 60% increase in compar- ison with the control column. The least axial and lateral deflections were 93% and 72% which were from columns repaired with ferrocement material. The cracks in the interface and its propagation developed with sequential increment of load and new cracks started to form at zones closer to the upper face in contact with the machine. Bulging and peeling of mortars characterised the failure pattern of the CCs’. Acrylic polymer and ferrocement jacket repaired columns showed an improvement which came close to the strength of the unrepaired.Item Reinforcement bar corrosion - causes and management(IOP Publishing Ltd, 2019) Oki, M.; Akintola, S. A.; Adediran, A. A.; Peter, P.; Ikubanni, P. P.; Ogunsemi, B. T.Concretes are composite materials which decay as a result of steel corrosion in concrete structures is mostly accelerated in environments laden with chlorides and industrial effluent gases as well as harsh chemicals employed in and those generated from wastes in agricultural industries. This review summarises the effects of various environmental pollutants which promote deterioration of concretes with resultant corrosion of reinforcing bar (rebar). An overview of traditional and current methods for significant reduction of this mode of material deterioration is described. Discussions on management tools for rebar corrosion in agricultural and marine environments have been highlighted. Repair methods include the traditional application of patch repair mortar which has been modified with polymeric materials to improve adhesion and reduce porosity. The use of cathodic protection system to reduce rebar corrosion to its barest minimum has gained currency. Attention should be directed at corrosion reduction practices at the design and planning stages as well as modification concrete mixes with modified agricultural wastes/products and polymers.Item Simulation studies of shear stresses in reinforced and non-reinforced concrete structures(2009-06) Akindahunsi, A. A.; Ajayi, J. A.; Oluwole, O.A simulation study of the shear stresses in non-reinforced and reinforced structures was carried in this work. Using the finite element method and equations of elasticity, columns and concrete deck of a simple storey structure were subjected to plane strian conditions. The results showed that proper reinforcement causes stresses to be directed into the reinforcements with the resultant transverse shear at critical joints of the structure. In the insufficiently reinforced member, the resultant shear of the concrete resulted in load transfered to the reinforcement itself with the resultant buckling of reinforcement and eventual collapse of structure.