International Research Journal of Engineering and Technology (IRJET) Volume: 04 Issue: 02 | Feb -2017
www.irjet.net
e-ISSN: 2395 -0056 p-ISSN: 2395-0072
Effect on Compressive Strength of Concrete by Partial Replacement of Cement with Fly ash Rishabh Joshi1 1Assistant
Professor, Department of Civil Engineering, Shri Ramswaroop Memorial University, Lucknow, Uttar Pradesh, India.
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Abstract - The cement is the main ingredient used for
concrete. The production of cement involves emission of large amount of carbon dioxide into the atmosphere. Therefore, the search of any other such material which can be used as an alternative to cement should lead to lowest possible environmental impact. The fly ash obtained by combustion of coal can be used as partial replacement for cement owing to its pozzolanic nature, which provides strength to cement. The huge quantity of fly ash being accumulated over the years is likely to pose a serious threat for its disposal and cause environmental problems. In this paper, an effort has been made to determine the effect on compressive strength of concrete by partial replacement of cement with 0%, 10%, 20% and 30% of fly ash for M20 grade of concrete. Test results indicate that workability and durability of concrete increases with increase in fly ash content. It has also been obtained that with increase in fly ash content, there is reduction in compressive strength of concrete. The optimum replacement of cement with fly ash is 30%. Key Words: fly ash, workability, durability, partial replacement, pozzolanic, compressive strength.
1. INTRODUCTION Energy is the main backbone of modern civilization of the world, and the electrical power from thermal stations is a major source of energy on which hinges the functioning and growth of manhood. Energy in the form of electricity is a basic necessity for economic development and social progress. Thermal power electricity is generated from the coal fired thermal stations. Coal based thermal power stations generate electricity on one hand which is essential for our development and growth, on the other hand, these power stations also produce massive quantities of coal ash which could pose serious environmental and other related problems. Fly ash is one of the coal combustion products, composed of the fine particles that are driven out of the boiler with the flue gases. Ash that falls in the bottom of the boiler is called bottom ash. In modern coal-fired power plants, fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys. Depending upon the Š 2017, IRJET
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source and makeup of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (Si ), aluminium oxide ( and calcium oxide (CaO). In the past, fly ash was generally released into the atmosphere as it is difficult to decompose, but air pollution control standards now require that it be captured prior to release by fitting pollution control equipment. Fly ash is generally stored at coal power plants or placed in landfills. Due to the presence of pozzolanic activities, which is responsible for setting of concrete and provide concrete with more protection from wet conditions and chemical attack, fly ash can be used as a partial replacement for cement. Moreover, cement industry is the major contributor of pollution by releasing carbon dioxide. 1 ton of cement produces approximately 1 ton of carbon dioxide. So by partially replacing cement with pozzolanic material such as fly ash, the cement industry can serve both the purposes of meeting the demands of construction industry and at the same time producing green and clean environment. Fly ash is of two types class F and C. Class F fly ash is produced by burning of harder, older anthracite and bituminous coals. This fly ash is pozzolanic in nature and contains less than 7% lime (CaO). However, class C fly ash is produced by burning of younger lignite sub-bituminous coal. It possesses pozzolanic as well as self-cementing properties. In the presence of water, class C fly ash hardens and gets stronger over time. It generally contains more than 20% lime (CaO).
2. LITERATURE REVIEW The present study aims to study the effect of fly ash on concrete by partial replacement of cement with 0%, 10%, 20% and 30% of fly ash. Various research works have already been conducted to study the effect of fly ash on various properties of concrete at different ages and for different grades of concrete. Some research works were reviewed and are presented in this paper. C. Marthong [1] studied the effect of fly ash additive on concrete properties and found that the normal consistency increases with increase in the grade of cement and fly ash content. It was also concluded that the use of fly ash improves the workability of concrete. Moreover, it was also ISO 9001:2008 Certified Journal
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