Influence of adding waste polyethylene terephthalate plastic strips on uniaxial compressive and tensile strength of cohesive soil

Unconfined compressive strength and tensile strength are important geotechnical characteristics whichare used for performance prediction and mix design in civil engineering projects. In recent years, theuse of waste materials as reinforcement elements such as glass, rubber and plastic waste increasedsignificantly. Nowadays, the use of polyethylene terephthalate (PET) has grown substantially for drinkbottles which is one of the most important environmental hazards. In the current study, the effect ofadding PET strips as reinforcement elements to a clayey soil has been studied by unconfinedcompressive strength and tensile strength tests. The compressive and tensile strengths of reinforcedspecimens with different PET contents (0%, 0.4%, 0.6%, 0.8% and 1% by the soil weight), lengths (12mm to 21 mm) and widths (3 mm and 6 mm) have been investigated. It was found that addition of thePET strips to the clay resulted in an increase in both the compressive and tensile strengths. The optimumPET content was dependent on the both width and length of the PET strips. The maximum UCS was321 kPa which observed in the specimen containing 0.8 % PET strips with 3 mm width and 18 mmlength. The maximum tensile strength was 33 kPa which observed in the specimen containing 0.6 % ofPET strips with 6 mm width and 15 mm length. The reinforced specimens containing I-shape PETelements exhibited a higher UCS value than that of the reinforced specimens with PET strips in mostcases which is may be due to increase of friction between the soil particles and the PET elements.