Mechanism and Effect of Activating Agent on Mechanical Performance of Steel Slag Composite Materials

ABSTRACT

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 SO₄^2- 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.

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