Static and dynamic mechanical properties of sedimentary rock after freeze-thaw or thermal shock weathering

• Impact tests are applied on rock before and after freeze-thaw/thermal shock cycles.
• Strain rate effects on mechanical behaviors of weathering-damaged rock are studied.
• Mechanisms of hydro-thermal effects during rock weathering process are analyzed.
• Water effects during weathering are summarized as solvent effect and medium effect.
• For rock weathering, temperature works by thermal deformation and phase-transition.

Rocks in engineering works and as building materials are always suffering freeze-thaw (F-T) and thermal shock (TS) weathering, and engineering rocks usually involve responses to impact loads from blasting operation, mechanized construction and seismic oscillation. Sedimentary rock distributes extensively and is important for engineering geological and hydrogeological works. For a deeper understanding of the F-T and TS effects on the rock behaviors, physical tests, static compressions and dynamic impacts were carried out on red-sandstone free from and after artificial F-T or TS cycles in this work. Laboratory tests show the significant physic-mechanical deterioration of red-sandstone after F-T or TS weathering. Compared to fresh specimens, red-sandstone after 10 F-T or TS cycles performs poorly in both the static compression and SHPB impact tests, and F-T/TS induced decreases of UCS and modulus are more remarkable under dynamic impacts than under static loads. Dynamic mechanical behaviors of both fresh and F-T/TS weathered red-sandstone have distinguishable strain rate effects, and water content significantly affects the strain rate effects on mechanical behaviors. Water and temperature variation play important roles in the rock weathering process. In this work, water effects during the rock weathering process were summarized as solvent effect and medium effect, while temperature variation damaged red-sandstone meanly in two ways, non-uniform thermal deformation of mineral grains and phase-transition of water.