Several studies have been conducted on the use of plastic
wastes in concrete to improve its compressive strength. Choi et al. (2005)
showed that the effect of plastic waste as aggregates on properties of concrete
could reduce the weight by 2-6% of normal weight and compressive strength by up
to 33% compared to the normal concrete. In this study, High Density-Polyethylene
(HDPE), the specific type of plastic bottle was used as aggregates in concrete
mixtures. With a high strength-to-density ratio, HDPE is used in the production
of plastic bottles, corrosion-resistant piping, geo-membranes, and plastic
lumber. HDPE is commonly recycled, and has the number “2” as its resin
identification code (Onveos, 2017). Resin Identification Code is used to
identify the plastic resin out of which product is made (Wilhelm, 2016).
Moreover, HDPE plastic bottles have good strength that can be used as an
alternative aggregates for making concretes.