Influence of recycled tyre amendment on the mechanical behaviour of soil-bentonite cut-off walls

Generation of the scarp tyre has increased in recent years, and finding innovative reusing methods is of interest to researchers. This study aims to investigate the hydraulic conductivity and one-dimensional consolidation behaviour of soil-bentonite (SB) backfill amended with powdered recycled tyre (PRT) and crumbed recycled tyre (CRT) by performing a series of oedometer consolidation and rigid-wall hydraulic conductivity tests. Three values of PRT and CRT (i.e., 2%, 5% and 10% by dry weight) were used to prepare the specimens. The investigation on vertical strain-time graphs showed that the addition of PRT and CRT caused an increase in settlement characteristics of the SB backfill. The results also showed that the addition of PRT and CRT caused an increase in the compression index (Cc) and the swelling index (C-s) of the SB specimens. The coefficient of consolidation (c(v)) based on the Casagrande and Taylor methods showed a consistent increasing trend by increasing the PRT and CRT. The hydraulic conductivity was computed based on the Terzaghi consolidation theory (k(theory)), and the results showed that increasing the PRT and CRT caused an increase in hydraulic conductivity of the SB backfill. The hydraulic conductivity (k(f)) measured using a rigid-wall permeability compaction mould showed a similar increasing trend by increasing the PRT and CRT contents of the backfills. (C) 2017 Elsevier Ltd. All rights reserved.