Effect of Acid Solution Treatment on Properties of Steel Slag Particle and Stripping Action to Asphalt

The expansibility of steel slag has a negative impact on the volume stability and strength of asphalt mixtures. Treating steel slag with an acid solution can obviously reduce its expansibility. But the influence of the acid treatment on other properties of steel slag is still unclear, so it is necessary to study the changes in these properties. The influence of citric and acetic acid solutions on the corrosion effect, expansion rate of converter steel slag, and its stripping action on AH-70# asphalt was systematically investigated in this paper. A series of tests were conducted, including acid solution immersion and expansion test of steel slag, as well as stripping action assessments between steel slag and asphalt. Digital image processing technology was utilized to analyze the acid corrosion effect and grade the stripping action to asphalt. The findings revealed that acid solution treatment results in mass loss of the steel slag, with both mass loss and water absorption rates increasing as the solution concentration is heightened. These properties also intensify with the extended immersion durations. Notably, the treatment with an acid solution has a significant impact on the roundness and flatness ratios of steel slag with a diameter of 9.5 mm, but the treatment does not substantially modify the acid corrosion effect of steel slag larger than 13.2 mm. The treatment significantly diminishes the expansion rate of steel slag, with the maximum reduction observed at 39%. A linear correlation was identified between the expansion rate and mass loss, suggesting that greater mass loss correlates with a reduced expansion rate posttreatment. Acid solution treatment leads to a decrement in the stripping grade of steel slag to asphalt, with the most pronounced reduction being three grades. The immersion and boiling water methods were found to be equivalently effective in evaluating the stripping action of acid-treated steel slag to asphalt.