A Study on Manufacture of Concrete by Utilizing Waste Products at Thermal Powerhouses

Abstract

It is reported in a recent paper that manufacture of concrete by utilizing cinder ashes of pulverized coal burnt at thermal powerhouses has been developed. The cementing materials that are by-products of fine cinder ashes, furnace slag, quick lime and some mixtures, are called CS cement, and they have as high as 600kg/cm2 of compressive strength when they are mixed at high rotating speed and steam curing is applied to them. In the present paper is presented a brief report of experimental study made on the use of CS cement.(1) The efficiency of the retarder used to control the heat generation of the quick lime is remarkably affected by the temperature of the mixture. When the temperature of the mixture is at 50°C the retarder is of no use.(2) The physical properties of CS cement is affected by the CaO content. The CaO ratio at 25% is favorable for the setting and strength of the cement, but for its soundness and drying shrinkage the favorable CaO ratio is at 15%. The drying shrinkage of CS cement is smaller than that of normal portland cement.(3) A special mixer with a rotating cone has been developed so designed as to retain coarse aggregate in the concrete. The result of the test shows that the concrete has 450kg/cm2 of compressive strength with 500kg/m3 of cement content. Ordinary portland cement is suitable for water curing concrete, but CS cement is more suitable for steam curing.Cinder ashes are excellent cementing material for manufacture not only of ordinary mortar and concrete, but of light-weight concrete and artificial aggregate.