Sulphoaluminate modified carbon steel slag and use method thereof

The invention provides sulphoaluminate modified carbon steel slag, a preparation method of which comprises the following steps: mixing carbon steel slag and a modifier to form a mixture A; pressing and forming: pressing the mixture into a material cake B; calcining: calcining the material cake B in a high-temperature furnace at 1220-1230 DEG C to form a material cake C; quenching: cooling the material cake C in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 DEG C, and quenching the material cake C to room temperature to obtain sulphoaluminate modified carbon steel slag D; and powder preparation: grinding the sulphoaluminate modified carbon steel slag D into fine powder, then adding 5% of dihydrate gypsum as a grinding aid, and carrying out ball milling together with the modified carbon steel slag to obtain the modified carbon steel slag powder. After the modifier is added into the carbon steel slag, the carbon steel slag is mixed with cement mortar, the activ