Mechanical properties and acoustic emission characteristics of basalt fiber reinforced cemented silty sand subjected to freeze-thaw cycles

Freeze-thaw (F-T) cycling was a crucial issue in seasonal frozen zones and it will significantly influence the mechanical properties of soil, which must be strictly considered for subgrade engineering. Therefore, a series of unconfined compression test was conducted to analyze the effects of multiple factors i.e., fiber content, fiber length, curing time and F-T cycles on unconfined compression strength (UCS), as well as find the optimal ratio of fiber reinforced cemented silty sand. Meanwhile, based on the optimal ratio, AE test was adopt to further evaluate the AE characteristic parameters (i.e. cumulative ring count and cumulative energy, energy, amplitude, RA and AF) of fiber reinforced cemented silty sand subjected to F-T cycles, to reveal the F-T damage process. The results showed that the UCS first increased and then decreased with the increase of fiber content, increased with the increase of curing time, decreased with the increase of fiber length and F-T cycles, and stabilized after 6 ~ 10 cycles.. The optimal ratio was 0.2% fiber content, 12 mm fiber length and 14 days of curing. Moreover, AE characteristic parameters had a great correlation with the damage stages. The F-T damage could be divided into three stages by cumulative ring count and cumulative energy. The sudden change in AE amplitude symbolized the transformation of damage stage. The amplitude of 67 dB after 6 F-T cycles could be used as an early failure warning.