Investigation of the effect of stabilizing subgrade soils with recycled glass powder on freeze–thaw resistance

The purpose of this research is to determine the freeze–thaw performance of subgrade soils when stabilized using recycled glass powder (CT). Ensuring the durability of pavement foundations under varying climatic conditions is a key engineering requirement, especially for highways in cold regions. Sandy and clayey soils with different CT contents were prepared, and both untreated and stabilized specimens were subjected to Standard Proctor and unconfined compressive strength (UCS) tests after 7 days of curing. Results showed that CT addition improved strength, with optimum values at 9% CT for clayey soil and 12% CT for sandy soil. Freeze–thaw resistance was assessed by subjecting untreated and optimum CT-stabilized specimens to 3, 6, and 12 cycles, each consisting of freezing at –23°C for 24 hours and thawing at 23 ± 2°C for 23 hours. The 7-day UCS values (0 cycle) were used as references. The results showed that the strength increased by 1.82 times in clay soil samples containing 9% CT and by 1.37 times in sandy soil samples containing 12% CT. It was determined that the highest strength and weight loss occurred at the end of 12cycles. The losses decreased to 78.90% and 1.36% with 12% CT addition, and to 60.64% and 0.78% with 9% CT addition, respectively. The use of CT enhanced both the compressive strength and freeze–thaw resistance of the soils; recycled glass powder can be considered an effective stabilization material, especially for areas exposed to freeze–thaw effects.