Abstract: Under neutron irradiation, silicate aggregates in concrete are highly prone to amorphous transformation, which in turn gives rise to radiation-induced volume expansion of aggregates (RIVE). Driven by the volume expansion of silicate aggregates, the initiation of microcracks takes place inside the concrete matrix, and as such microcracks form and further develop and propagate continuously, the mechanical properties of concrete will undergo a gradual degradation process. Investigating the microscopic amorphization transformation mechanism of silicate aggregates represented by quartz (SiO₂) under the action of neutron irradiation is a core and essential approach to elucidating the irradiation damage mechanism of silicate aggregates in concrete and gaining a deeper and comprehensive understanding of the intrinsic mechanism of concrete mechanical property degradation induced by neutron irradiation. Based on the classic molecular dynamics simulation method, this study established a precise atomic-scale SiO₂ crystal model by utilizing the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and adopted the ReaxFF force field to systematically investigate the structural evolution characteristics, defect generation rules and volume change laws of quartz crystals under different energy deposition conditions in detail. The simulation results clearly indicate that with the continuous accumulation of deposited energy in the quartz crystal system, the quartz crystal structure undergoes an irreversible transition process from the gradual accumulation of localized point defects to the overall complete amorphization. The mass density of quartz shows a monotonous decreasing trend with the continuous increase of deposited energy, and ultimately stabilizes at a constant value of 2.20 g/cm³, with a reduction of approximately 17% in contrast to its initial state. Furthermore, the concentration of radiation-induced point defects in the quartz crystal exhibits an approximate linear correlation with the unit cell volume. The typical covalent network structure of SiO₂ causes the atoms surrounding the defects to move away from the defect center to a certain extent, and this microscopic structural change constitutes the essential microscopic essence of the obvious expansion effect exhibited by quartz materials at the macroscopic level.