The Effect of Fiber Type and Size on the Strength and Ductility of Fly Ash and Fiber Stabilized Fine-Grained Soil Subbase

摘要

This study investigates the effects of the type and size of randomly oriented polymeric fibers on the strength and failure strain of fly ash stabilized high plasticity soil. Three different lengths of 13 mm, 25 mm, and 50 mm of two types of fibers, one with low (polypropylene) and the other with high (polyethylene) tensile strength were mixed (1%) with high plasticity clay soil and Class C fly ash (10%). The mixtures were compacted to prepare specimens for unconfined compression test and split tensile test at the same dry unit weight. The fiber inclusions increased the compressive and tensile strength of fly ash stabilized soils significantly. The 25 mm fiber specimens with an aspect ratio of 0.45 that is the length of the fiber to the diameter of soil specimen, showed the maximum enhancement of strength for both compressive and tensile strength. Although all the specimens failed due to pullout of the fibers, the specimens with different fiber showed different strains at failure. The 13 mm fiber specimens (aspect ratio of 0.22) showed minimum increase in failure strain, whereas the specimens prepared with 25 mm and 50 mm fibers showed the maximum increase in failure strain, and failure did not occur even at 15% strain. The length of fiber has a relatively lower impact on gaining strength, but has pronounced effect on the ductility of the soil. The failure strain increased at least 132% when the 25 mm fiber was used. The polyethylene fiber stabilized soil showed slightly higher strengths because of its higher tensile strength and elastic modulus.