<p>To clarify the mechanical behaviour of type I fractured sandstone under dry wetting (D-W) cycles and to quantify how strain rate influences its uniaxial compression performance under various D-W conditions. Three-point bending tests were first conducted on fractured sandstone subjected to increasing D-W cycles. Uniaxial compression tests were then performed at multiple strain rates under each D-W condition. Porosity evolution during cycling was monitored and employed to define a damage variable, while energy accumulation, dissipation and transformation were tracked throughout loading. The results indicate that compressive strength rises monotonically with strain rate, whereas peak strain decreases; in the presence of sodium sulfate solution, physico-mechanical properties and brittleness progressively decline with additional D-W cycles, accompanied by a pronounced increase in plasticity; cyclic D-W treatment produces visible surface deterioration—holes, pockmarks and rounded edges; the proposed damage variable, derived from porosity changes, provides a quantitative measure of material degradation. The combined influence of D-W cycling and strain rate governs the strength–deformation response of fractured calcareous sandstone. Energy-based analysis reveals that degradation is driven by continuous energy accumulation and dissipation during loading, offering a mechanistic explanation for the observed deterioration.</p>