Preparation and application of gangue-based artificial aggregate using silicone mold casting method

• A reverse-engineered cold-bonded granulation process using silicone mold casting was developed, enabling precise control over aggregate morphology and particle size distribution with significantly simplified operational procedures. • Artificial lightweight aggregates produced with high-volume solid wastes (coal gangue, slag, and fly ash) demonstrate complete replacement capability for natural aggregates while effectively mitigating the performance variability of raw coal gangue. • Life cycle assessment (LCA) verifies that the G4-G7 formulations maintain required mechanical properties while exhibiting substantial advantages in carbon emission reduction and ecological benefits. In response to the ongoing demand for natural aggregates in the construction industry and the urgent need for green utilization of solid wastes, a preparation method for multi-source solid waste-based artificial lightweight aggregates using a silicone mold casting technique is proposed. The artificial lightweight aggregates were composed primarily of coal gangue, slag, fly ash, basalt fibers, a small amount of cement, and water, with quartz sand, waste glass, and a superplasticizer as supplementary components. They were fabricated via a process of mixing, cold-bonding, and subsequent natural water curing, successfully obtaining products with a specified particle shape coefficient.The physical and mechanical properties of the aggregates under seven different mix proportions were systematically evaluated: apparent density 800–900 kg/m³, water absorption around 10 %, and crushing index 9.27 %–15.18 %, along with the compressive strength of the resulting concrete. Experimental results demonstrate that even with 100 % replacement of natural aggregates, the concrete can achieve C30-grade strength, exhibiting high structural integrity and good aggregate–matrix synergy in failure mode. XRD and SEM analyses indicate that the aggregates possess a dense internal structure and complete hydration reactions. LCA-based environmental assessment shows that the production of these aggregates can achieve significant carbon reduction, with optimized groups (G4–G7) even exhibiting net negative carbon emissions, while simultaneously enabling large-scale solid waste utilization and energy savings. This study provides a technically feasible, environmentally friendly, and economically viable solution for valorizing coal gangue and other solid wastes, contributing to the green and low-carbon transformation of the construction materials industry.