The Quantification and Evolution of Particle Characteristics of Saturated Silt under Freeze–Thaw Cycles

Abstract

Freeze–thaw action is a complicated process. How it affects particle characteristics of saturated silt may provide a much clearer understanding of its internal mechanism. A series of specific apparatus were developed for sample reconstitution, including sand pluviation device, freeze–thaw device, and special sampling device. After reconstituting samples by sand pluviation method and a specific parameter-controlled freeze–thaw testing, scanning electron microscope (SEM) and laser scattering and transmissometry (LST) tests were conducted to explore the particle characteristics of silt under freeze–thaw cycles. The test results show that freeze–thaw action could probably induce the particles’ (60–200 μm) breakage, also affecting the clay particles’ (less than 5 μm) aggregation. With the increase of freeze–thaw times, freeze–thaw action on the particle impact decreases. The larger the effective confining pressure, the lower the freezing temperature, greater the compaction degree, and higher the fine content, which can all aggravate the effects of freeze–thaw action on silt particles. Finally, two characteristic evolution modes of particle structure under freeze–thaw cycles have been inferred based on particle interaction during the freeze–thaw process, which could provide a reference for long-term durability evaluation of pavements in cold regions.