Abstract: The application performance of rock chips generated during TBM excavation in hard rock sections is often unsatisfactory when used in concrete. To address this issue, three-dimensional (3D) laser scanning and image processing techniques are employed herein to quantitatively analyze the morphological characteristic differences between rock chips and conventional crushed-stone coarse aggregates. Subsequently, the effects of various substitution methods on the workability and mechanical properties of concrete are examined. The results show that: (1) The cumulative distribution curve for sphericity of 4.75－19.00 mm rock chips is opposite to that of crushedstone coarse aggregates, whereas the trends for angularity and texture index are similar. Moreover, rock chips exhibit wider distribution ranges for sphericity, angularity, and texture index. (2) Within the same particle size range, rock chips show lower average sphericity but higher angularity, texture index, and 3D fractal dimension than crushed-stone coarse aggregates. (3) Differences in sphericity, angularity, and 3D fractal dimension between rock chips and crushed-stone coarse aggregates increase with increasing particle size, while the texture index first increases and then decreases. (4) Replacing the coarse aggregates with rock chips markedly affects concrete workability and mechanical properties. Conventional substitution methods result in poorer concrete performance. Meanwhile, the small-particle-size substitution method yields optimal results because the particles possess higher sphericity, more complex angularity, and richer surface texture. (5) In practical engineering applications, the small-particle-size substitution method using 4.75－9.50 mm rock chips is recommended, with the substitution rate controlled within 20%.

Key words: TBM rock chips, morphological characteristics, crushed-stone coarse aggregates, substitution method, concrete performance