Acetic Acid Modified Steel Slag via Dry Chemical Modification Method for Enhancing the Hydraulic Reactivity

To activate the early-age hydraulic reactivity of steel slag powder (SS), a method of using acetic acid (AA)-anhydrous alcohol solution to modify the SS via dry chemical modification technology was proposed. The compressive strength and hydraulic reactivity of SS pastes and SS blended cement pastes were investigated, then the mineral composition, surface morphology and specific surface area of unmodified SS and AA modified SS were characterized. The results show that calcite, portlandite and dicalcium ferrite in SS react with AA to produce calcium acetate and pores in the modified process, thus leading to AA modified SS with the greater specific surface area and rougher surface. Water is easier to absorb onto the surface of modified SS and enters the inner of SS particles along the pores, resulting in higher dissolution heat and reaction heat of active minerals in SS. The result show that, the higher 72 h cumulative hydration heat, the 3 d, 7 d and 90 d compressive strengths of AA modified SS pastes and AA modified SS blended cement pastes are obtained, compared to the unmodified pastes.