Abstract
This study investigates the potential use of ferroalloy slag from the Aksu Ferroalloy Plant (Aksu, Pavlodar region, Kazakhstan) as a road construction aggregate. A bulk stockpile sample was characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). FTIR spectra and XRD patterns reveal a predominantly silicate matrix composed of feldspar-type aluminosilicates, clinopyroxenes (diopside), and minor quartz, with nanocrystalline phases embedded in a glassy background and no evidence of free CaO or periclase. SEM images show angular, blocky particles with rough, cracked surfaces and limited vesicular porosity, indicating a dense, rock-like texture favorable for mechanical interlock. EDS analysis confirms a silica-rich, aluminosilicate composition (≈60 wt.% SiO 2 , 13 wt.% Al 2 O 3 , 12 wt.% MgO, 5 wt.% CaO) with significant MnO and only ≈1 wt.% Cr 2 O 3 , corresponding to an acidic to weakly basic slag. Compared with the CaO-rich BOF steel slags and MgO- and Cr-rich ferrochrome slags widely reported in the literature, the Aksu slag is chemically more stable and less reactive, making it a promising candidate primarily as unbound or asphalt aggregate, subject to standard mechanical and environmental verification.