How do you make a granite facing mix for precast panels? We plan to use a granite coarse aggregate which is predominantly white but which contains flecks of black. We've made trial mixes with white cement and with gray cement, as well as with mixtures of the two, but none seems to give us the color we want.
Try adding some blue mineral pigment. Use white cement only and add about 0.05 percent blue mineral pigment by weight of cement. This will give enough tint to overcome the stark white of the white cement, but not enough to make the observer conscious of the presence of blue color. For many years the Portland Cement Association has been using 0.06 percent blue pigment by weight of cement in producing precast "granite" safety trophies which it awards to cement manufacturing plants that establish excellent safety records. Such trophies may be seen prominently displayed in front of many American and Canadian cement plants.