Enhancing Strength in Concrete with Partial Replacement of Cement by Fly ash and Basaltic Dust

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Addis Ababa University


Owning to its local resource availability and its adaptability to prevailing environment, construction industry using concrete is common here in our country, Ethiopia. Therefore, enhancing strength in concrete structures has a lot of advantages over prevailing country’s socio- economics. Presently large amount of fly ash is generated in thermal power plants as a waste material with an improper impact on environment and humans. Fly ash, a waste generated by thermal power plants is as such a big environmental concern like ‘Reppi Electric power Station’ here in our country, Ethiopia. Therefore, economic concern and green environment issue should be addressed as many last studies shows as reduction of CO2 emissions and waste materials like fly ash and basaltic dust are being used instead of cement as cementations materials recently. Hence, using waste materials, fly ash and basaltic dust will improve structural strength of concrete than the conventional concrete production one in addition to its cost and make green environment by depleting above mentioned wastes, fly ash and basaltic dust. The cement has been replaced by fly ash and basaltic dust accordingly in the range of 0% (without fly ash and basaltic dust), 10%, 20%, 30%, 40% and 50% by weight of cement for OPC, C-30. These tests were carried out to evaluate the mechanical or structural properties of the concrete for the test results of Compressive Strength, Split Tensile Strength and Flexural Strength for 7days, 14days and 28days respectively. Based up on the test result obtained, Cement partial replacement by both fly ash and basaltic dust with 30% with slump test of 35-36.5mm induced best result in Compressive strength (42.47MPa) and attractive structural properties of the concrete with respect to the conventional one and higher results of Split tensile strength (2.94MPa) and Flexural strength (4.63MPa) were obtained with 20% partial replacement of cement with fly ash and basaltic dust while maintaining constructability by using water to cement ratio of 0.54. Hence it would minimize construction cost, avoid delay in construction as early strength can be obtained earlier, and enhance structural strength of the prevailing concrete and keeping the environment green from CO2 emissions and fly ash disposal pollutions.



Basaltic Dust and Fly Ash, Compressive Strength, Constructability, Enhancing Strength, Flexural Strength, In Situ Cast, Split Tensile Strength, Precast