Comparative Study of Silica Fume, Fly Ash and Cement Mixes for Production of High Strength Concrete

Abstract

This paper presents the result of mix design developed for high strength concrete. It involves the process of determining experimentally the most suitable concrete mixes in order to achieve maximum strength with least economic expenditures. Recent developments in concrete technology, especially during the last decade have made it possible to produce the High Strength Concrete (HSC) on commercial scale. The advantages of using high strength concrete are numerous, as it can economize variety of construction works such as long span bridges, offshore structures and high rise buildings. The concrete mixtures contain high cement contents, low water cement ratio, high quality aggregates and several admixtures (such as a super plasticizer and Pozzolana). When properly mixed, consolidated and cured, such mixtures give high strength, durability and excellent performance. . Ordinarily, concrete of substantially higher compressive strength is used for pre-stressed structures than for those constructed of ordinary reinforced concrete. Almost all pre-stressed construction in the world at present is designed for a compressive strength well above 5000 psi. In this research work, coarse aggregate of nominal specified size from Margala and locally available fine aggregate with specific fineness modulus were used. In this research work four mixes were selected to achieve a compressive strength up to 9000 psi. Four type of mixes for developing HSC were used including pure cement, 12% silica fume, 6% silica fume & 6% fly ash and 12% fly ash as a partial replacement of cement with a fixed water cement ratio of 0.36.Chemrite NN was used as super plasticizer.