Abstract: During the construction of carbon storage spaces in residual mining areas, the evolution of mineral components in grouting materials induced by a CO₂-rich environment directly affects their rheological behavior and the long-term stability of the storage space. In this study, nanoindentation experiments were conducted in combination with X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) to obtain mineral element distributions and indentation morphologies, thereby revealing the meso-rheological mechanism of red mud-fly ash based grouting material (RFGM) after carbonation curing. The results show that carbonation curing increases the mass fraction of CaCO₃ crystals by 20.7%, and the resulting “carbonated shell” on the material surface enhances its early-age creep resistance. However, local Ca²⁺ leaching due to carbonation weakens the mechanical properties in certain zones, making them more susceptible to deformation. Nanoindentation rheological tests further indicate that during the creep unloading stage, the creep recovery capacity of conventional carbonated spots (i.e., the weakened zones) under high loads is significantly lower than that under low loads. During the elastic aftereffect holding period, higher prior creep loads intensify microcrack propagation and particle-boundary sliding at all indentation points, leading to a more pronounced elastic aftereffect. The Burgers model effectively fits the observed rheological behavior, characterizing the superior deformation resistance and drastic changes in elastic recovery in the carbonation-enriched zones. This study elucidates the meso-rheological behavior mechanism of RFGM in a CO₂ environment, providing a theoretical basis for ensuring the structural integrity and long-term stability of carbon storage spaces in residual mining areas.