Effect of Size of Tire Granules on the Interface Shear Behavior of Bottom Ash–Tire Granule Mixture with Geosynthetics

This study examines the engineering behavior of a lightweight composite mixture composed of tire granules and bottom ash. The effects of the size of tire granules and type of reinforcement on the shear strength and compressibility of the bottom ash tire granule mixture were estimated through large-scale direct shear tests. The addition of tire granules of size less than 4.75 mm resulted in a greater reduction in the peak shear strength of the mix and increased compressibility compared to mixtures with tire granules of size greater than 4.75 mm. The interaction coefficient of the composite mixture with geotextile was observed to be more than one with an addition of 10% rubber content. In case of geogrids as reinforcement, the composite mixture comprising 40% large-tire granules and 20% small-tire granules demonstrated the most significant interface shear strength when compared to geotextiles. The effect of the grid aperture size was visible in the mixture consisting of large-tire granules with less than 30% rubber content. The transverse ribs of the geogrid provided sufficient bearing resistance in addition to the frictional interlock in the shear strength mobilization. In addition, a significant reduction in plastic strain was observed owing to the preloading of the composite mixture.