Experimental investigation of using reclaimed asphalt pavement aggregate in scrap tire encased stone column

Stone column is one of the cost effective techniques for improving soft soil layers. Since in the construction process of stone column, weak soil is replaced with stiffer material, appropriate method to bury the waste materials e.g. reclaimed asphalt pavement (RAP) and scrap tires, is to use as stone column materials. The aim of this study is the application of scrap tires for enclosing stone columns and RAP mixed with gravel for stone column, to provide an environmental friendly and cost-effective improvement method for weak layers. In order to investigate the behavior of such stone columns, experimental modeling of the unit cell consisting of a single stone column with reclaimed asphalt pavement as filler material and encasing it by scrap tires has been carried out. RAP contents of 0%, 25%, 50%, 75% and 100% are selected to investigate effects of different mixing ratios. Loading capacity tests were performed on encased and non-encased stone column specimens. Results of loading capacity tests show that encasing of stone columns with scrap tires improves the loading capacity significantly. On the other hand by increasing the RAP ratio from 0% to 100%, the stone column loading capacity changes. However the amount of change in the bearing capacity is not significant and therefore the use of stone column made of 100% or any percentage of RAP is reasonable.