Synergistic interaction between ceramic waste powder and PET waste for enhanced durability performance of cement mortars

Abstract The increased disposal of plastic waste has raised significant environmental concerns, prompting interest in its reuse within the construction sector. Incorporating two types of waste into cementitious mixtures presents a sustainable and synergistic approach to enhance the performance and mitigate the environmental impact. The aim of this study is to investigate the possibility of the combined use of ceramic waste powder (CWP) and polyethylene terephthalate (PET) plastic shreds in cement mortar to achieve sustainability and reduce CO 2 emissions. Mortar mixes were prepared by incorporating 10% CWP as a partial cement replacement and varying PET content (0–20%) as fine aggregate. The experimental program was conducted in two phases. In the first stage, an assessment of the fresh and hardened properties under normal conditions was presented. The investigation included slump flow, density, thermal conductivity, and ultrasonic pulse velocity (UPV). The second phase evaluated durability under aggressive conditions: elevated temperatures (300°C–600°C for 3 h) and chemical exposure to 5% magnesium sulfate and sulfuric acid for 1 month. Microstructural analysis was performed to evaluate deterioration. Results indicated a significant reduction in flow diameter at 20% PET content. Based on UPV results, a proposed novel Specific Quality Indicator (SQI) was introduced to evaluate the quality of PET mortar. Compressive strength decreased from 35 to 27 MPa at 300°C and from 30 to 10 MPa at 600°C, with more pronounced degradation observed under acid exposure. At high PET content, the flexural strength under sulfate attack was reduced and greater weight loss. Nevertheless, the integration of CWP and PET waste has potential for sustainable mortar production, provided that optimal proportions are maintained.