Tensile Strength and Toughness of Soil–Cement–Fly-Ash Composite Reinforced with Recycled High-Density Polyethylene Strips

Abstract

An experimental investigation was conducted to evaluate the split tensile load-deformation strength and toughness properties of a granular soil chemically stabilized with cement and fly ash, and mechanically reinforced with recycled plastic strips [high-density polyethylene (HDPE)] obtained from postconsumer milk or water containers. The primary objective of this research was to evaluate if a modest amount of reinforcing fibers derived from recycled plastics can enhance the mechanical performance of a lean cementitious composite by improving the split tensile strength and the postpeak load carrying capacity. As an extension to the ASTM C 496 procedures for split tensile tests, two lateral linear variable differential transformers were attached to measure the tensile deformation of the horizontal diameter due to loading in the orthogonal direction; this method permitted an evaluation of the fiber toughening action under split tension. Two major groups of mixes were used for the study. The first group was stabilized with only 2–5% cement, while the second group contained 10% cement (by weight); several specimens also contained an additional 2–10% ASTM class C fly ash. Fiber-reinforced specimens contained 0.25% (by weight) to 0.80% (by weight) of recycled HDPE. A dimensionless toughness index and a fiber factor were defined in order to quantify the improvement in strength and toughness characteristics. It was found that the inclusion of HDPE fibers does not meaningfully improve the tensile strength, but significantly enhances the overall toughness of the composite. Results indicate that the test procedure, and the toughness index and fiber factor proposed in this study can be utilized to evaluate the performance of a fiber-reinforced stabilized soil for geotechnical and pavement applications.