Correlation of sustainable material in Pozzolanic composite fly ash concrete

Abstract Rapid urbanization and population growth have increased the demand for concrete, worsening environmental issues like waste pollution and greenhouse gas emissions. This study explores the use of sustainable materials, specifically Polyethylene Terephthalate (PET) flakes and Metakaolin fly ash (MK), in concrete mix designs to support sustainable development. PET replaced coarse aggregates, while MK substituted Ordinary Portland Cement (OPC). The research evaluated compressive and splitting tensile strength. Initially, both conventional concrete (CTR) and PET-5 mixes with different water-cement (W/C) ratios were tested. A W/C ratio of 0.6 was optimal, achieving the desired strength of 25 MPa for both CTR and PET-5. Testing mixes with PET replacements of 5% to 15% identified PET-10 as the best-performing mix. In the final phase, PET-10 was combined with MK replacements (5% to 10%). The PET-10 + MK-7.5 mix achieved the highest compressive strength of 37.71 MPa, a 27% increase over PET-10, due to MK’s pozzolanic effect. Microstructural analyses confirmed chemical enhancements. PET-10 + MK-7.5 emerged as the optimal design, meeting sustainability goals and the target strength of 25 MPa. This study highlights the effective use of recycled and supplementary materials to enhance concrete strength and reduce environmental impact.