This document discusses a study that assessed the mechanical properties and workability of concrete reinforced with pure high-density polyethylene (HDPE) granules. Five mixtures with HDPE weight fractions of 1-5% were tested and compared to plain concrete. The HDPE-reinforced concrete showed improved compressive strength, flexural strength, tensile strength, ductility, energy absorption, and resistance to chemicals compared to plain concrete. The HDPE granules improved the concrete's properties without significantly impacting workability. Testing included compressive, flexural, and tensile strength tests performed according to appropriate standards.