Volume change behaviour and microstructure of stabilized loess under cyclic freeze-thaw conditions

Freeze-thaw action is considered to be one of the most destructive actions that can induce significant damage in stabilized subgrades in seasonally frozen loess areas. Laboratory tests including frost heave-thaw shrinkage and microstructure change during freeze-thaw cycles were conducted to evaluate the volume change rate of loess stabilized with cement, lime, and fly ash under the impact of cyclic freeze-thaw conditions. The loess specimens collapsed after eight freeze-thaw cycles (192 h), but most stabilized loess specimens had no visible damage after all freeze-thaw cycles were completed. All of the stabilized loess samples underwent a much smaller volume change than the loess alone after the freeze-thaw cycles. Although surface porosity and equivalent diameter of stabilized loess samples increased, the stabilized loess can retain its microstructure during freeze-thaw cycles when the cement content was less than 6%. To ensure freeze-thaw resistance of stabilized loess subgrades, the mix proportions of the three additives was recommended to be 4 to 5% cement, 6% lime, and 10% fly ash.