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<p>Red sandstone, characterized by well-developed porosity and strong water absorption capacity, provides a representative medium for investigating freeze–thaw deterioration in porous rocks. Although freeze–thaw damage has been widely studied, the role of saturation level in linking macroscopic degradation with pore-scale structural evolution remains insufficiently understood. In this study, red sandstone specimens with three initial saturation levels (0%, 50%, and 100%) were subjected to up to 50 freeze–thaw cycles. Macroscopic deterioration was evaluated using surface observations and P-wave velocity measurements, while pore-scale evolution of fully saturated specimens was characterized by highresolution X-ray computed tomography, three-dimensional reconstruction, pore–throat analysis, and lattice Boltzmann permeability simulation. The results show that increasing saturation generally intensified freeze–thaw deterioration. Fully saturated specimens exhibited the most evident surface damage, pore expansion, internal cracking, and permeability enhancement, whereas dry and partially saturated specimens showed relatively limited degradation. CT analysis showed that the porosity of fully saturated sandstone increased from 18.68% to 23.01% after 50 cycles, while the average fractal dimension increased from 2.44 to 2.53. The pore–throat system evolved from fine, weakly connected structures to coarser, more connected, and morphologically complex networks. Permeability increased most markedly in the interior region, with the maximum value rising from 9.57 Darcy to 25.60 Darcy, indicating that freeze–thaw cycling promoted internal pore coalescence and the formation of effective seepage pathways. The deterioration mechanism is interpreted as the coupled action of thermoelastic mismatch cracking and ice-induced cracking: the former contributes to microcrack initiation under repeated temperature fluctuations, whereas the latter promotes pore enlargement and crack propagation under high saturation. These findings clarify how water content controls freeze–thaw damage through both ice-induced pressure and porenetwork reorganization, providing pore-scale evidence for durability assessment of porous rocks in cold-region engineering and stone heritage conservation.</p>

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Deterioration characteristics and pore structure evolution of red sandstone with different saturation levels under freeze-thaw cycles

  • 期刊论文

  • 发表日期：

    2026年7月29日

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  • Liping Wang,
  • Xuanchen Pan,
  • Jing Wang,
  • Zhexiao Hao

摘要

Red sandstone, characterized by well-developed porosity and strong water absorption capacity, provides a representative medium for investigating freeze–thaw deterioration in porous rocks. Although freeze–thaw damage has been widely studied, the role of saturation level in linking macroscopic degradation with pore-scale structural evolution remains insufficiently understood. In this study, red sandstone specimens with three initial saturation levels (0%, 50%, and 100%) were subjected to up to 50 freeze–thaw cycles. Macroscopic deterioration was evaluated using surface observations and P-wave velocity measurements, while pore-scale evolution of fully saturated specimens was characterized by highresolution X-ray computed tomography, three-dimensional reconstruction, pore–throat analysis, and lattice Boltzmann permeability simulation. The results show that increasing saturation generally intensified freeze–thaw deterioration. Fully saturated specimens exhibited the most evident surface damage, pore expansion, internal cracking, and permeability enhancement, whereas dry and partially saturated specimens showed relatively limited degradation. CT analysis showed that the porosity of fully saturated sandstone increased from 18.68% to 23.01% after 50 cycles, while the average fractal dimension increased from 2.44 to 2.53. The pore–throat system evolved from fine, weakly connected structures to coarser, more connected, and morphologically complex networks. Permeability increased most markedly in the interior region, with the maximum value rising from 9.57 Darcy to 25.60 Darcy, indicating that freeze–thaw cycling promoted internal pore coalescence and the formation of effective seepage pathways. The deterioration mechanism is interpreted as the coupled action of thermoelastic mismatch cracking and ice-induced cracking: the former contributes to microcrack initiation under repeated temperature fluctuations, whereas the latter promotes pore enlargement and crack propagation under high saturation. These findings clarify how water content controls freeze–thaw damage through both ice-induced pressure and porenetwork reorganization, providing pore-scale evidence for durability assessment of porous rocks in cold-region engineering and stone heritage conservation.