Evaluation of one part alkali-activated self-compacting concrete with mining residue Available to Purchase

The construction industry’s rising emphasis on sustainability and durability has encouraged innovation in concrete materials. This study develops a one-part alkali-activated self-compacting concrete that utilises coal mine overburden (CMO) as a viable substitute for natural fine aggregate. The one-part alkali activation method increases practical application by using solid precursors rather than liquid activators, which removes the need to handle corrosive solutions. The primary precursor, ground granulated blast furnace slag, was combined with solid sodium metasilicate as the dry activator. The raw material properties of the CMO were studied to determine its suitability as a fine aggregate. Several mix design trials were conducted to achieve sufficient paste volume, consistent aggregate distribution, and workability. The developed concrete satisfied the requirements for M30 grade concrete with 28th-day compressive, split tensile, and flexural strengths of 39.55, 4.75, and 4.65 MPa, respectively. In addition, it showed low chloride ion permeability, minimal drying shrinkage (0.037%), and reduced thermal conductivity (1.20 W/m·K). These results indicate that CMO can be successfully added to one-part alkali-activated SCC as a fine aggregate substitute, offering a technically viable and sustainable solution.