Use Of Discrete Fibers For Tensile Reinforcement Of An Alternative Pavement Foundation With Recycled Aggregate

An experimental investigation consisting primarily of splitting tension and flexural tests was conducted to perform a comparative evaluation of various fibers used to reinforce a stabilized base course material containing recycled crushed concrete aggregate, Type I portland cement and ASTM Class C fly ash. Three commercially available steel and polypropylene fibers, as well as high-density polyethylene (HDPE) fiber derived from recycled plastics were used in this study as reinforcing agents. The primary objective of using fibers was to improve the tensile strength, crack resistance, and toughness characteristics of this alternative pavement foundation material, which is composed of more than 90% by weight of waste products. As an extension to the ASTM C 496 procedure for splitting tension tests, two lateral linear variable differential transformers (LVDT) were attached at the mid-height of the specimens for measuring the tensile deformation of the horizontal diameter due to vertical compressive loading in the orthogonal direction. This method enabled the determination of splitting tension load-deformation and toughness behavior of the specimens. A dimensionless toughness index is used to quantify the post-peak behavior of the specimens containing various reinforcing fibers. A new dimensionless parameter, PPSI (Post Peak Strength Index), is introduced, which combines peak tensile strength with the energy absorption capacity of the composite for evaluating the effectiveness of fibers in a lean cementitious mix. It is found that depending on the mix proportions, the specimens reinforced with recycled HDPE strips can perform as well as or sometimes better than those reinforced with commercially available fibers. These observations are certainly encouraging from economical and environmental perspectives.