Mechanical properties and abrasion behaviour of concrete containing shredded PET bottle waste as a partial substitution of natural aggregate

The purpose of this work is to evaluate the effects of size and shape of recycled polyethylene terephthalate (PET) aggregate on the fresh and hardened properties, including abrasion resistance, of concrete. 5%, 10% and 15% in volume of natural aggregate in the concrete mixes were replaced by an equal volume of three differently shaped and sized PET-aggregates. The results indicate that the slump of fresh concrete increases slightly with the incorporation of pellet-shaped PET-aggregate. Flakier plastic aggregate sharply decreases the slump of the fresh concrete and it further decreases if the content and size of this type of PET-aggregate increase. The compressive strength, tensile splitting strength, modulus of elasticity and flexural strength of concrete deteriorate due to the incorporation of PET-aggregate and the deterioration of these properties intensifies with increasing content of this aggregate. Differences in size, shape and texture of PET-aggregates change the water to cement ratio as well as the slump of fresh concrete mixes, which ultimately change the mechanical behaviour. Flaky PET-aggregates bridge the two separated concrete pieces and therefore prevent concrete from breaking apart after failure. The abrasion resistance of concrete mixes containing various types of PET-aggregate is better than that of the reference concrete. The abrasion resistance of concrete with incorporation of various types and contents of PET-aggregates can be related to its compressive strength.