Evaluating the effect of using shredded waste tire in the stone columns as an improvement technique

In this paper, shredded waste tires are used as a substitution for gravel materials and their effect on stone column's behavior is investigated. An experimental study is carried out on three sizes of tire shreds, including “Fine tire”, “Medium tire”, and “large tire”. The medium-sized tire shred has the same size as the gravel materials and the other sizes are selected smaller and larger. Thirteen series of large scale direct shear, large oedometer, and constant head permeability tests are carried out in three different volumetric mixture proportions of gravel and tire shreds. The results of the large scale direct shear box and large oedometer tests show an increase in the loading capacity of stone columns for 20% of tire content, however, for tire mixing ratios greater than 20%, the loading capacity of stone column is reduced. Furthermore, 20% of medium-sized tire shreds enhances the loading capacity by 30% and 15%, respectively, with no significant change in permeability. Therefore, it is concluded that the best performance of gravel tire shred admixture is achieved by the medium-sized tire shreds. Eventually, utilizing tire shred as partial replacement for gravel materials is an economic way to enhance the loading capacity of stone columns and also to solve environmental problems.