Interaction between Reinforcing Geosynthetics and Soil-Tire Chip Mixtures

TLDR

The study evaluates the mechanical properties of tire chips and soil‑tire chip mixtures for geosynthetic‑reinforced earthworks and assesses their potential advantages in retaining walls and embankments. Shear strength and pull‑out capacity were tested on tire‑chip and soil‑tire‑chip mixtures, using a woven geotextile and two geogrids, with mixtures prepared from clean sand and sandy silt. Results show that pull‑out force rises with displacement without a peak up to 100 mm, tire‑chip backfills have interaction coefficients >1 while soil‑tire‑chip backfills range 0.2–0.7, yet their pull‑out capacity is comparable or higher than plain soil, and the higher strength, lower weight, and better interaction of soil‑tire‑chip mixtures allow walls to use less reinforcement and embankments to be steeper with reduced material volume while maintaining lateral stability.

Abstract

The objective of the present study was to evaluate the mechanical properties of tire chips and soil-tire chip mixtures relevant to geosynthetic-reinforced earthworks. Tests were conducted to evaluate shear strength and pull-out capacity with a woven geotextile and two geogrids. Soil-tire chip mixtures made with clean sand and sandy silt were tested. These properties were then used to assess the potential advantages of using soil-tire chip backfills for geosynthetic-reinforced retaining walls and embankments. The test results show that the geosynthetic pull-out force in tire chip and soil-tire chip backfills increases with displacement—i.e., no peak pull-out force is generally obtained, at least for displacements ≤100 mm. Pull-out interaction coefficients for tire chip backfills are typically greater than 1, whereas for soil-tire chip backfills they typically range between 0.2 and 0.7, even though the pull-out capacity for soil-tire chip backfills is generally similar to or greater than the pull-out capacity in a soil backfill. The higher strength, lower unit weight and good backfill-geosynthetic interaction obtained with soil-tire chip backfills can result in walls requiring less geosynthetic reinforcement than walls backfilled with soil. In addition, embankments can potentially be constructed with steeper slopes and a smaller volume of material when soil-tire chip fill is used, while providing greater resistance against lateral sliding and foundation settlement.