This study investigates the effect of three kinds of activating agent on the mechanical performance of steel slag
composite materials. Hydration products of the pastes at different ages are investigated by XRD. The results show that
compared with the calcium hydroxide, gypsum and sodium sulfate can excite the activation of steel slag more effectively.
When amount of gypsum is 1.5%, the 3d strength increases to 1.2MPa, 7d strength increases to 3.3MPa, 28d strength
increases to 5.0MPa. Ca2+ and SO42- are provided by gypsum, SiO2, Fe2O3 and Al2O3 in steel slag act with Ca(OH)2,
hydration products such as hydrated calcium silicate, are generated in the paste. Enhancement of early strength may be
attributed to rapidly consumption of Al2O3 in steel slag and Ca(OH)2. When amount of Na2SO4 is 1.5%, the 3d strength
increases to 5.1MPa, 7d strength increases to 6.5MPa, 28d strength increases to 15.5MPa. XRD patterns show that the
main products are consist of hydrated calcium silicate, Aft and calcium hydroxide. These products are bonded together,
fill the void of paste, so the density increased, and higher strength are obtained.