Experimental investigation on the toughness of rice straw fibre reinforced lime soil under freeze–thaw cycles

Lime-reinforced soil is widely used for subgrades in seasonal freezing zones and is susceptible to brittle damage under vehicle loads due to its high brittleness. In view of this phenomenon, this research studied the toughening effect and mechanism of rice straw fibres on lime soil under the freezing and thawing cycles. Total energy absorption, post-peak energy absorption capacity, failure deformation, deformation index and brittleness index were determined through three-point bending tests. The change in soil toughness was studied from energy, deformation and strength criteria. Combined with soil microstructure, energy absorption and crack propagation, the reasons for soil toughness change and fibre toughening mechanism after freezing and thawing cycles were analysed. The experimental results indicated that the freezing and thawing cycles reduced the toughness of lime soil, while the fibres significantly contributed to the toughening effect on lime soil after several cycles of freeze-thaw.