Plastic waste buildup, especially the waste in the form of polyethylene terephthalate (PET) bottles, has turned into a serious environmental problem. The paper aims to investigate a sustainable solution through the upscaling of waste PET bottles into geocells for the reinforcement of weak soils. Geocells in different heights (3 cm, 5 cm, and 7 cm) were fabricated from waste PET bottles and connected by rivet nails to form a honeycomb-like structure. Engineering properties of clay were established by conventional testing methods. Both in the unsoaked and soaked conditions, California Bearing Ratio (CBR) tests were performed on unreinforced and reinforced specimens, with river sand and M-sand as the infill material. The geocells offered a three-dimensional confinement to the soil, resulting in efficient distribution of applied loads, reduction of lateral displacements, and enhancement in both the strength and stiffness. When they are unsoaked, the CBR values are higher because the soil is still strong and it has suction, and when they are soaked, the soil strength declines because it is saturated, but it also behaves as it would in the field more. The experimental results showed an increase in CBR values; the maximum increment was obtained for the 7 cm geocell filled with M-sand in the wet state as compared with the soil without reinforcement. The investigation confirms that waste PET bottles can be exploited as an environmentally friendly and economical geocell material for reinforcement of subgrade and thus enable sustainable solutions in geotechnical engineering.
Lakshmi et al. (2026) studied this question.