The invention belongs to the technical field of concrete preparation, and discloses a high-performance concrete admixture and a preparation method thereof, the high-performance concrete admixture is composed of the following components by
mass: 9-15 parts of limestone, 6-10 parts of
blast furnace water-quenched
slag, 5-6 parts of kaolin, 4-5 parts of desulfurized
gypsum, 2-4 parts of
alumina, 2-3 parts of a synergist, 1-3 parts of carbon
powder, and 1-2 parts of nano silica. The carbon
powder is physically treated by utilizing the characteristics of
dispersity promotion, defoaming property, rheological property and the like of
silicon dioxide, the excellent properties of
dispersity promotion, enhancement, defoaming,
rheology, sagging prevention and the like are shown in the material, the
dispersity of all the components in concrete can be improved, and the
viscosity and gas content of a mixture are reduced, so that the working performance and the post-hardening
mechanical property of the concrete mixture are improved. The preparation process is simple, raw materials are easy to obtain, and cost is low.