Carbon black for coloring cement and method for coloring cement-formed product

Abstract

The present invention provides a carbon black for coloring cement excelling in dispersibility in cement slurry, exhibiting superior adhesion to a cement matrix, and excelling in coloring characteristics and strength, and a method for coloring a cement-formed product using the carbon black. The carbon black for coloring cement is a carbon black in which humic acids are adsorbed on the surface by a surface treatment using an aqueous solution in which the humic acids are dissolved. The carbon black is preferably a carbon black on which humic acids are adsorbed by wet-granulation and drying using an aqueous solution in which the humic acids are dissolved as granulation water. The coloring method includes adding and mixing a water suspension in which carbon black, on which the humic acids are adsorbed, is dispersed in water with cement slurry, or directly adding and mixing carbon black on which the humic acids are adsorbed with the cement slurry, thereby coloring a cement-formed product.