Development of sustainable high-performance binders comprising a large volume of multiple coal-based solid wastes via a dual-activation strategy

• A sustainable high-performance binder incorporating a large volume of multi coal-based solid wastes was developed. • The pozzolanic reactivity of coal gasification slag was enhanced via the combined planetary ball-milling and chemical activation. • Cementitious systems with less efficient portlandite consumption developed heterogeneous microstructures that failed via brittle, shear-dominated cracking along weak internal interfaces. • Combination of physical encapsulation within the dense C-S-H matrix and chemical binding within the hydration products prevents the leaching of heavy metals. To advance the resource-efficient utilisation of coal-based solid waste (CBSW), this study developed a low-carbon cementitious binder containing ∼70 wt.% CBSW, thereby substantially reducing cement consumption. Using three typical coal-based solid wastes—coal gasification slag (CGS), coal slime (CS), and fly ash (FA)—this work systematically evaluates: (1) the dual activation of CGS and the thermal activation of CS; (2) hydration evolution and microstructure development together with the governing micromechanisms; (3) strength, deformation, and damage evolution under uniaxial compression; and (4) environmental compatibility, life-cycle performance, and economic assessment. The proposed activation treatments significantly enhanced the pozzolanic reactivity of CGS and CS by releasing more amorphous silicon and aluminium. At 28 d, formulation CNC2 achieved the highest compressive strength (23.98 MPa), followed by CNN2 (23.11 MPa). Notably, quantitative acoustic emission (AE) hit statistics indicate that CCN1 exhibits a markedly higher proportion of high-average-frequency events (average frequency, AF > 200 kHz; 27.12%) than CNN2 (12.03%), consistent with a more tensile-dominated microcracking process and delayed catastrophic instability. The high-CBSW, low-carbon materials demonstrated robust mechanical performance, meeting stringent strength requirements for high-stress mining applications. Microstructural analyses indicate that the micromechanical response is governed by activator chemistry. Optimised formulations improved durability through synergistic C–(A)–S–H formation and space-filling phases, whereas excess Friedel’s salt or retained CH (Ca(OH)₂) crystals promoted microcracking and localised porosity. Leaching tests on three representative samples (CCN1, CNN2, and CNC2) confirmed that heavy metal ion concentrations were well below regulatory limits and that the formulations exhibited highly favourable carbon footprints. These findings support using CBSW-cement-based materials in mining engineering as a viable strategy to cut costs, reduce waste, and improve sustainability.