During concrete processing, such as pumping or casting, its flow behaviour relies on rheological properties, e.g. time and shear-dependent viscosity and yield stress which requires a clear understanding and modelling of these properties. A scale-bridging approach is proposed, starting from the micro-scale (cement paste) to the macro-scale (concrete). The microscale analysis included the study of microstructural changes under shear and at rest, with integrated Focused Beam Reflectance Measurements (FBRM) used to assess the agglomeration state. These experimental results were combined with Computational Fluid Dynamics coupled with Discrete Element Method (CFD-DEM) simulations to develop models focusing on particle and fluid properties. Shear-induced particle migration and interparticle shear rate between larger particles were considered for upscaling. Meso-scale investigations using real-time particle tracking in model mortars provided new insights into particle motion under shear, particularly with larger sands showing more dominant migration. Meso-scale resolved CFD-DEM simulations were used to interpret the physics of particle migration, highlighting the importance of the interparticle shear rate. Shear-induced particle migration and interparticle shear rates were found to be critical parameters for upscaling from micro- to macro-scales, with estimates suggesting up to a tenfold increase in the ratio of interparticle shear rate to global shear rate for model mortars. These results highlight the importance of considering these factors for effective scale-up in concrete processing.