The packaging sector widely uses polyethylene terephthalate (PET). However, because PET takes 100 years to degrade, it creates a problem for the environment. We initiated a study to mitigate this challenge. We prepare the polymer using waste PET bottles. We made PET resin with a 30:70 PET to Glycol ratio and added it to cement at 6, 12, and 18% using the initiator Methyl Ketone Peroxide (MEKPo). We made PET resin with a 30:70 PET to Glycol ratio and added it to cement at 6, 12, and 18% using the initiator Methyl Ketone Peroxide (MEKPo). We substituted cement with fly ash at 10, 20, and 30%, and tested the applicability of both the fresh and hardened phases. The study found that PET resin in conventional cement mortar and fly ash mortar improved both tensile and compressive strength of concrete. Fly ash replacement showed an improvement in strength. The 18% PET resin content has a negative impact on mortar strength. At 1, 7, and 28 days, there is a positive impact on tensile strength with and without fly ash in PET resin. The increment in water penetration and abrasion resistance with addition of PET resin and fly ash.