Multiscale Investigation of Manufactured Sand Characteristics on 3D Printed Concrete Performance (2026-02)¶

With the diminishing availability of natural river sand, manufactured sand (MS) has gained prominence as a superior substitute, owing to its advantages of controllable quality and resource abundance. This study employs multiscale characterization and theoretical analysis to evaluate the morphological features of tuff, granite, and basalt sands, systematically investigating the influence of particle shape and stone powder (SP) content (0–15%) on the rheological behavior, pore structure evolution, hydration kinetics, and printability of the concrete. Statistical analysis identifies the roundness coefficient (Ro) as the primary morphological index, exhibiting a robust correlation (r > 0.94) with the fractal dimension (Fd). Furthermore, aggregates characterized by higher surface roughness and fractal dimensions are found to promote early-stage hydration heat evolution and reaction rates. Key findings reveal that an optimal SP dosage of 10% significantly densifies the matrix through a micro-filling effect; this optimized mixture achieves a maximum vertical build height of 632 mm, corresponding to a static yield stress of 2325.41 Pa. Conversely, excessive SP content (> 10%) causes a drastic surge in plastic viscosity, leading to printing failure. These quantitative insights provide a robust theoretical foundation for the mixture optimization of MS-based 3D printed concrete.