Recent population and industrial growth require innovative approaches for recycling construction materials for civil infrastructure such as railways, roads, and building foundations. This study adopts a combination of expansive black soil blended with coal wash (CW), a by-product of coal mining, to produce a resilient substructural fill for railroads. When considered individually, expansive clays and CW are prone to high swell pressure, shrinking and swelling, excessive degradation, and relatively low bearing capacity, properties that would adversely affect infrastructure. This current study i...