Mechanical properties of fiber reinforced lime stabilized clay before and after freeze-thaw effect

Lime is known to be a hydraulic binder, particularly used in stabilization of soils of relatively high plasticity. On the other hand, fiber materials of high aspect ratio is used for reinforcement of soils, which help to constitute a structure counteracting the tensile stresses occuring in stabilized medium. In this study, the effect of inclusion of different types of fiber materials on clay/lime stabilized clay is investigated within an experimental framework. Lime stabilized clay samples reinforced using basalt or polypropylene fibers were subjected to standard Proctor, freeze-thaw, unconfined compressive strength and ultrasonic pulse velocity tests in order to determine their compaction and mechanical properties. A similar program excluding ultrasonic wave velocity tests were carried out on fiber reinforced specimens free of lime. Furthermore, selected specimens were subjected to Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) analyses to determine the microstructural aspects of stabilized medium. As expected, strength of clay/lime stabilized clay was improved by inclusion of both types of fibers. Although strengths of lime stabilized soils reinforced with polypropyene fiber was greater than those reinforced with basalt fiber in general, greatest strength was observed in 90-day cured basalt fiber reinforced specimen of fiber length, fiber content and lime content of 19 mm, 0.75% and 9%, respectively. Freeze-thaw effect was observed from the results of either strength or ultrasonic pulse velocity tests, these values are decreased due to freeze-thaw action. Losses in mass of specimens were determined along with measurements of ultrasonic pulse velocity and unconfined compressive strength by evaluation of the interrelationships among these parameters. Lastly, attempts using several numerical methods were made to model the strength of stabilized soils.