O. Hadad; O. Soltani; H. Azizian; V. Mam Ghaderi
Abstract
Due to the increasing use of concrete, researchers and engineers are constantly tried to improve its mechanical and physical properties as well as its efficiency. Hence, they have made use of the most diverse products and the most modern concere technologies. In the present study, oak bark ash and macro ...
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Due to the increasing use of concrete, researchers and engineers are constantly tried to improve its mechanical and physical properties as well as its efficiency. Hence, they have made use of the most diverse products and the most modern concere technologies. In the present study, oak bark ash and macro fly ash have been used as the most widely used pozzolans in the concrete industry. The parameters of concrete and the percentages of materials used in its structure remained constant, but different percentages of oak bark ash and macro fly ash have been added to the mix design. Brazilian method and bending strength of concrete was applied. The parameters of concrete density, concrete consistency, compressive strength, and tensile strength have been investigated..Therefore, the existing materials required necessary tests; based on obtained resulted, an optimal design for the concrete mix was introduced from which the necessary specimens were taken into consideration. Then, oak bark ash was used as an additive, in proportions of 0.2 and 0.4% by the total weight of cement, and macro fly ash was used to replace cement as a variable in various proportions of 5, 10, 15 and 20% by total weight of cement. Based on the existing variables and the control design, a total of 15 groups of mix designs were introduced. The statistical population includes 45 cubic specimens (15×15×15), and 45 cylindrical specimens (15×30) for tensile strength test using Brazilian method. Also 45 bending beam specimens having dimensions of 10×10×50 were examined. Finally, after analysis of the obtained results, we dentified the superior mix design had the best performance and that both additives affected all studied parameters, including concrete consistency, density, compressive strength, tensile strength, and bending strength of concrete. However, macro fly ash had a great effect on the conrete strength. The obtained results also indicated that excessive use of any additive could have adverse effects on the mechanical properties of the concrete.
O. O. Obiukwu; J. Igboekwe
Abstract
Fibre content effects on mechanical, surface morphology and chemical resistance of epoxy/rattan fibre composite was investigated. By analysis of scanning electron microscopy (SEM), mechanical and chemical examinations. SEM shows the rattan fibre had improved facial adhesion and a fairly uniform distribution ...
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Fibre content effects on mechanical, surface morphology and chemical resistance of epoxy/rattan fibre composite was investigated. By analysis of scanning electron microscopy (SEM), mechanical and chemical examinations. SEM shows the rattan fibre had improved facial adhesion and a fairly uniform distribution of fibre in the matrix. Similar result were observed for flexural and tensile strengths with gradual increase in strengths with filler loading. Mechanical properties improved with increasing fibre loading, peaking at 25 wt % content. The best tensile and impact strength was obtained at 25 wt % filler with a value of 19.271Mpa and 18.876 J/m. There was a 4.48 % increase in hardness obtained at 15 wt %, 6.55 % increase in hardness at 20 wt. %, while 7.46 % increase in hardness was obtained at 25 wt % representing the highest hardness for individual fibre wt % considered. The flexural strength obtained for the samples presented increased as fibre content increased, while the best flexural strength result of 27.542 Mpa was observed at 25 wt. % fibre. The rattan - epoxy composite’s weight reduced greatly after testing in 10% HCl, NaOCl, and NaOH solution. Theresult for immersing in H2O2 solution showed negligible effects and hence, a small reduction in weight loss.