Effects of freeze–thaw cycles on a fiber reinforced fine grained soil in relation to geotechnical parameters

Abstract Freeze–thaw cycling is a weathering process which occurs in cold climates during winter and spring. At temperatures just below 0 °C, ice lenses which tend to form in free spaces between soil aggregates, force them apart and end up the alteration of characteristic structures in micro and macro scales. In most of the previous studies, changes in physical and chemical properties of soils were investigated. This study was conducted to manifest the effect of using polypropylene fibers in a fine grained soil during freeze–thaw cycles. A clayey soil, reinforced with 0.5, 1 and 1.5 percentages of polypropylene fibers, was compacted in the laboratory and exposed to a maximum of 9 closed-system freeze–thaw cycles. It has been found that for the investigated soil, unconsolidated undrained triaxial compressive strength of unreinforced soil decreases with increasing the number of freeze–thaw cycles, whereas reinforced sample shows better performance and the strength reduction amount decreases from 43% to 32% by reinforcing the soil samples. This effect is caused by acting polypropylene fibers as tensile elements between the soil particles as it is demonstrated with scanning electron microscope (SEM). In addition reinforcing can also reduces the effect of freeze–thaw cycles on the changes of cohesion of the soil.