TECHNICAL FEASIBILITY OF USING STEEL SLAG AS RAILWAY BALLAST: FINE PARTICLE GENERATION AND ELECTRICAL RESISTIVITY

Steel slag has emerged as a promising alternative to natural rock for railway ballast applications. Although its mechanical performance is often comparable or superior to that of conventional ballast, key challenges remain. This study evaluates its technical feasibility, focusing on electrical resistivity and the generation of cementing fines (powdery material). Experimental evaluated apparent density, apparent porosity, water absorption, expansion, Treton impact resistance, Los Angeles abrasion and electrical resistivity. The slag presented an apparent density of 3,122 kg/m3, water absorption of 2.0%, and apparent porosity of 5.5%, the latter exceeding standard limits. Mechanical performance was satisfactory, with Treton and Los Angeles abrasion indices of 9.6% and 20.3%, respectively. The analysis of Treton and Los Angeles abrasion over successive cycles indicates that steel slag tends toward rapid stabilization, resulting in high residual strength and reduced progressive degradation. In terms of electrical behavior, slag showed high resistivity in dry conditions (2,580,000 Ω·m), but values dropped significantly with moisture, reaching around or below 60 Ω·m. The presence of slag powder and iron ore fines further reduced resistivity, with minimum values of 27.9 Ω·m. Consequently, steel slag ballast is unsuitable for tracks using track circuit detection systems, but it can be applied in sections equipped with axle counter systems.