Investigation on the Mechanical Properties and Microscopic Characteristics of Modified Steel Slag Concrete under Sulfate Erosion

Abstract

In this study, cement-fly ash composite slurry was used to modify the surface of steel slag aggregate. The evolution law of parameters such as the mass loss rate, dynamic elastic modulus, and compressive strength of the modified material was obtained through the erosion test, and the sulfate erosion was investigated by X-ray diffraction and scanning electron microscopy techniques. The results show that the modification of steel slag aggregate can significantly reduce damage to steel slag concrete during the erosion process. The quality and dynamic elastic modulus of concrete both increased first and then decreased with the erosion time. The compressive strength after erosion was higher than that of ordinary steel slag. Aggregate concrete and ordinary concrete increased by 5.7% and 15.6%, respectively. The microscopic characteristic analysis found that the modified coating filled the pores and microcracks on the surface of the steel slag, making it difficult for SO42- to invade. The number of corrosion products inside the sample was significantly reduced. Additionally, the steel slag aggregate and the active components in the modified coating could interact, resulting in the hydration products effectively filling in the pores and microcracks of the modified concrete, so that the compactness of the modified steel slag aggregate concrete was significantly improved.