Fly Ash-Granulated Rubber Mixture as Lightweight Geomaterial

In recent times, fly ash and scrap tires are being utilized extensively in geotechnical applications as a fill material due to their favourable properties. Many studies are reported indicating the suitability of soil-tire waste mixtures as geomaterials. In the present study, the viability of using a mixture of granular rubber and fly ash is explored. Granulated rubber of nominal size equal to 9.5 mm, and fly ashes collected from different thermal power plant sources in India are used in the study. Granulated rubber is mixed with fly ash particles in different proportions, i.e., 0%, 9%, 23%, and 37%, and 100% (granulated rubber with respect to the total weight of the mixture). The optimum mix of granulated rubber and fly ash is proposed based on the minimum void ratio obtained on compacted mixtures. The optimum content of granulated rubber is found to be in the range of 35-65% of the mixture (by weight). The shear strength of fly ash-granulated rubber mixtures is tested in large-size direct shear apparatus (size equal to 300 mm x 300 mm x 200 mm; in length, in width, and in width). The shear strength of the mixture is found to increase with the increase in percentage of granulated rubber. In the present study, the variation in the shear strength of mixtures in relation with the volumetric strain response of the mixtures is discussed. The transition of volumetric response from dilative to contractive is observed for the range of granulated rubber-fly ash mixtures tested and is discussed based on granular void ratio