ECO FRIENDLY UTILIZATION OF WASTE PET BOTTLES AS PARTIAL REPLACEMENT OF SAND AND BAGASSE ASH AS PARTIAL REPLACEMENT OF CEMENT IN CONCRETE

This research aimed to investigate and introduce locally available materials, PET (Polyethylene Terephthalate) and Bagasse ash, as partial replacements for sand and cement, respectively, in concrete. The overall goal was the eco-friendly utilization of waste PET bottles as a partial replacement of sand and bagasse ash as a partial replacement of cement in concrete. Specific objectives included analyzing the physical and chemical properties of these materials, investigating their effects on concrete characteristics (workability, unit weight, quality, and strength), and determining the optimum proportion for substitution. The ACI mix design was used for the experimental analysis. The methodology involved casting cubical specimens (150 × 150 × 150 mm) from concrete mixtures where sand was replaced by PET and cement was replaced by bagasse ash, separately and simultaneously, at 0%, 5%, 10%, and 15% substitution levels. Testing was conducted to determine the fresh and hardened behavior of the concrete, including workability (slump), unit weight, compressive strength, and Ultrasonic Pulse Velocity (UPV). The experimental results showed a reduction in unit weight, pulse velocity, and compressive strength. However, an increase in slump values (workability) was observed in the modified concrete mixes. Crucially, despite the reduction in strength, the strength achieved at the 15% replacement level (17.943 MPa or 2601.735 psi) still satisfied the minimum specified compressive strength (2500 psi) for structural concrete as per ACI 318 Standard Section 5.1.1. This approach significantly contributes to sustainability by demonstrating that 99.610 kg/m³ of sand and 73.756 kg/m³ of cement can be saved at the 15% replacement level. Future research is suggested to investigate these materials in self-compacting and high-performance concrete and to use treated bagasse ash to enhance its pozzolanic properties.