Experimental and theoretical validation of a prediction model for self-compacting concrete filling performance in rock skeletons

The flow-filling performance of Self-Compacting Concrete (SCC) in rockfill structures has a decisive impact on its ultimate cementation quality. In recent years, there has been a growing body of international research on the flow behavior of SCC in complex media. However, most studies still focus primarily on yield stress alone, with significant deficiencies remaining in the analysis of multi-parameter synergistic effects and real-time monitoring of internal flow processes. To address this gap, this study simultaneously considers the combined effects of yield stress and plastic viscosity on the flow behavior of SCC and, for the first time, integrates electrical resistivity sensors to dynamically capture the flow process of SCC within rockfill structures. By constructing a mathematical model based on fractal theory, we achieved high-precision prediction of SCC flow time (R² = 0.9148, RMSE = 1.76 s, MAE = 1.67 s). Additionally, we propose a comprehensive analytical framework that integrates theoretical flow models, flow blocking theory, and granular blocking mechanism effects to systematically explain the transport laws of SCC in heterogeneous rockfill structures. Dimensionless parameter λ and Cemented Filling Index (CFI) are employed to quantify filling morphology and compaction levels. Our findings indicate that higher yield stress and plastic viscosity of SCC inhibit its longitudinal flow capability, leading to concrete accumulation near the pouring point and enhanced lateral diffusion. Larger coarse aggregate sizes can reduce plastic viscosity and increase longitudinal flow velocity but also heighten the risk of particle blockage. Smaller rockfill sizes result in lower filling efficiency due to more complex pathways. Conversely, larger rockfill sizes, while beneficial for longitudinal compaction, lead to insufficient surface filling. The slope gradient of rockfills regulates SCC flow patterns through gravitational forces. A moderate slope of 1:2 achieves a balance between longitudinal penetration and slope-parallel flow, ensuring adequate filling depth, although specimens still exhibit relatively high internal porosity. This study not only expands the theoretical foundation of SCC flow mechanisms in complex porous media but also provides critical technical support for efficient construction of projects such as cemented rockfill dams.