Application of Concrete Incorporating Both Condensed Silica Fume and Fly Ash at Fancuo Hydropower Station

Abstract

This paper presents experimental results on the use of concrete incorporating condensed silica fume and fly ash to reduce cement content, to lower temperature rise due to hydration, and to enhance early strength. The paper gives a case history on the application of this type of concrete in the construction of turbine shells in China. Studies were done on the effect of adding different amounts of silica fume and fly ash on strength, the effect of addition of both silica fume and fly ash on the total heat of hydration, and properties of concrete, including setting time, slump loss, modulus of elasticity, ultimate elongation, impermeability, and resistance to abrasion. Experimental and field studies indicated that the concrete mixture containing condensed silica fume and fly ash helped save 38 percent cement, lower the heat of hydration by 40 percent, and showed a slight increase in strength and durability. In placing over 200 m³ of concrete of this type in hot weather, no abnormal phenomena occurred during the operation. A 90-day compressive strength of 30 MPa and a 98 percent strength were obtained, meeting the design strength requirements. No crack has been found in the surface of the shells since they were completed half a year ago.