Effects of reinforcing granular columns with fibres generated from plastic bottle waste

Ordinary and reinforced granular columns were both tested in a laboratory to study the effect of internal reinforcing using plastic fibres which were generated through the recycling of post-consumer PET bottles. A series of vertical compression tests were undertaken to understand the impact of varying the moisture content of the silt bed and the fibre concentration. Prepared samples were vertically loaded up to a maximum compression of 50 mm and the load-vertical deformation characteristics were electronically recorded. Post testing, the deformation behaviour of the column was physically modelled using a paste of plaster of Paris to obtain the maximum bulging diameter. In general, reinforcing the granular columns enhanced the load carrying capacity, although the degree of improvement was dependent on the testing conditions. For experiments conducted on the softer silt beds, an increase in fibre content resulted in higher loading strengths. The largest enhancement was recorded in the test with wetter silt, and the fibre concentration was 0.1 %. This was equivalent to 3.5 times that which was recorded when an ordinary granular column was installed. In terms of lateral deformation, the smallest bulge was obtained in the test with the wetter silt and a fibre content of 0.025 %.