Properties of tartaric acid modified steel slag as supplementing cementitious materials

Abstract

By using tartaric acid (TA) as a wet‐method modifier to modify steel slag powder (SS), it is helpful to reduce the content of free calcium oxide (f‐CaO) in SS and further improve the mechanical properties and soundness of SS as supplementing cementitious materials (SCM) in the mortar. The results indicate that with the addition of 2 wt% of TA, the number of large particles bigger than 45 µm in the SS decreased, resulting in predominantly smaller particles smaller than 45 µm. While the specific surface area increased from 417 to 704 m2/kg, the water consumption at standard consistency was significantly reduced. The soundness of the paste SS as SCM had improved including the f‐CaO content decreased from 4.81% to 0.95%, and the Le Chatelier expansion reduced from 4.5 to 1.5 mm. The mechanical properties were significantly enhanced, with the flexural strength increasing from 5.6 to 7.8 MPa, and the compressive strength rising from 38.8 to 52.7 MPa. After 28 days of curing in water, the hydration products of the mortar are hydrated calcium silicate (C‐S‐H), calcium hydroxide (CH), and calcium carbonate (CaCO3).