Abstract: An object of the present invention is to manufacture a material for concrete by using a fresh concrete sludge as a starting material. The invention relates to a method of manufacturing a material for concrete in which a material for concrete is manufactured from a slurry composed of a fresh concrete sludge obtained by treating a fresh concrete waste to separate a coarse aggregate and a fine aggregate. The manufacturing method comprises a grinding step of obtaining a product containing fine particles with a mean particle size of 10 ?m or less by wet grinding the slurry under a condition of water content of 60 wt. % or more.

Abstract: The invention provides an exhaust gas treatment agent characterized in that it comprises calcium silicate hydrate particles having a mean particle diameter of 0.2 to 4 &mgr;m and a specific surface area of not less than 60 m2/g and calcium hydroxide particles having a mean particle diameter of not more than 4 &mgr;m and the content of calcium hydroxide particles in both particle components is within the range of 20 to 60% by weight; a method of producing the exhaust gas treatment agent; and a process for the treatment of exhaust gases and soot and dust which uses the exhaust gas treatment agent.