Construction and Demolition Waste as Valuable Resources for Geosynthetic-Encased Stone Columns

Abstract

In this study, the possible utilization of mixed construction and demolition waste (CDW) is evaluated for constructing geosynthetic-encased stone columns. A detailed geotechnical characterization is presented, including investigation of the physical, mechanical, and hydraulic properties of the CDW. Further, the performance of a group of 36 geosynthetic-encased stone columns (GECs) constructed using CDW (CDW-GECs) is investigated by 3D numerical modeling. Both the load-bearing ability and the settlement characteristics of the CDW-GECs showed similar performance to that of GECs made of natural crushed stone aggregates (CSA-GECs). Vertiсаl stresses imparted to the CDW-GEC were 3 times the tоtаl vertiсаl stresses imparted tо the surrоunding sоil, resulting in a stress concentration ratio of 3. This is due to the better stiffness оf the CDW-GECs compared with the surrounding soil and soil arching effect. The CDW-GECs helped in dissipating excess hydrostatic pressure developed in the clay by acting as a vertical drain. Around 65% of the total settlement happened during construction itself. Maximum hoop tension in geosynthetic encasement of the CDW-GECs was developed at a depth of 2.5 times the diameter of the column and was 15 kN/m. The maximum value of hoop tension decreases as the distance of the stone column from the center of the embankment increases. Tension mobilized in the basal geogrid was in agreement with the differential settlement pattern with a maximum value near to the center of the embankment, which is found to be 23 kN/m. The present study indicates that CDW can be considered as a sustainable and valuable resource for the construction of geosynthetic-encased stone columns.