Civil Engineering
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Civil Engineering
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Item Flexural Strength of Revibrated Concrete Using Iron Ore Tailings (IOT) as Partial Replacement for River Sand(Journal of Research Information in Civil Engineering,, 2020-10-10) YUSUF, Abdulazeez; A. I. EmmanuelRiver sand is one of the major concrete constituents. Sand mining from rivers results in several environmental problems which leads to destruction of river banks among others. The use of IOT as a substitute for river sand is capable of addressing this problem. The effect of partial replacement of river sand with IOT on the flexural strength of revibrated concrete was studied in this paper. Sieve analysis, bulk density specific gravity and water absorption tests were conducted on the IOT, river sand and crushed granite to ascertain their suitability for use in concrete. A mix ratio of 1:2.1:2.7 and water-cement ratio of 0.5 was used to prepare concrete mixes with 0%, 10%, 20%, 30%, 40%, 50%, and 100% IOT as sand replacement. A total of 63 prisms of size 100 x 100 x 500 mm were cast and revibrated 30s for 3 minutes within 1 hour to provide samples to be tested for flexural strength at 7, 14 and 28 days curing age. Results revealed that the workability of concrete decreased with increase in percentage of IOT. Highest flexural strength was noted with concrete containing 100% IOT at all curing ages. Flexural strength model was proposed as a function of % IOT at 28 days curing age. It was recommended that IOT can be used as either partial or total replacement for river sand in concrete.Item Reliability studies on reinforced concrete beam subjected to bending forces with natural stone as coarse aggregate(Springer, 2021-10-10) Daniel Ndakuta Kolo; James Isiwu Aguwa; Theophilus Yisa Tsado; Mohammed Abdullahi; YUSUF, Abdulazeez; Sikiru Folahan OritolaThis paper presents the results of structural reliability analysis of a structural element (beam) in building using First-order reliability method (FORM) to ascertain the level of safety. The natural stone (NS) which is the by-product of Precambrian deposits of the Bida trough was used as coarse aggregate: unwashed and washed aggregates were used. A total of 80 concrete cubes of 150 mm × 150 mm × 150 mm were cast and used for this study, sensitivity analysis was conducted by varying the span, depth, effective depth, area of shear reinforcement and dead load of the beam in bending. The result of the sensitiv ity analysis revealed that the beam utilising unwashed and washed NS are both structurally safe at a span of 3000 mm with probabilities of failure of 9.20 × 10–5 and 2.06 × 10–8 and both safe at a depth of 600 mm with probabilities of failure of 4.19 × 10–4 and 2.602 × 10–4, respectively, in bending.