HEAT INSULATING CEMENTLESS CONCRETE MADE FROM SECONDARY MINERAL RESOURCES

摘要

A new composition of heat-insulating cementless concrete made from mineral by-products was developed. The concrete was developed on the basis of a new composite cementless binder incorporating the following materials: 80 % high-calcium ash, 10 to 15 % burnt sand and 5-10 % high alumina product. These three components were ground simultaneously in a planetary activator mill where the mechanochemical interaction between the amorphous silica of the burnt sand and free CaO of the ash occurred. The compressive strength and the optimum surface area of the binder were 40 to 60 MPa and 750 m~2/kg, respectively. The blend sets rapidly when mixed with water. The materials used for concrete were as follows: fly ash and furnace bottom ash sand from a thermal power plant, molding sands known as burnt sands from the foundry production and the high alumina product (HAP) from the abrasion works. The compressive strength and average density of the concrete were 0.25 to 5 MPa and 200 to 800 kg/m~3, respectively. The heat-insulating concrete was prepared in a turbulent mixer by introducing of a composite plasticizing and air-entraining admixture (technical grade lignosulfonate and the detergent called "Progress") into the mixture. The cost of the concrete is reduced by a factor of 1.5 to 2 compared with that for the conventional cement concrete.