Elevated‐temperature performance of green concrete incorporating glass waste and cardboard ash

Abstract This study examines how cardboard waste ash (CWA; 0%, 5%, 10%, 15%) and glass waste sand (GWS; 10%) jointly influence concrete compressive strength, mass loss, and ultrasonic pulse velocity (UPV) at ambient conditions and after exposure to 250, 350, 450, and 550°C. At ambient temperature, compressive strength was lowered by GWS, and strength was further reduced by adding more CWA; yet, at higher temperatures, CWA significantly enhanced thermal stability. Among the blends under investigation, the mixture with 5% CWA and 10% GWS provided the best overall balance of high‐temperature performance across the 250–550°C range, exhibiting the smallest strength loss at 450°C (8.3% relative to ambient) compared to the 0% CWA mix (22.9%). The 5% CWA mixture exhibited similar resistance to strength loss (14.4%) at the temperature of 550°C compared to the 10% CWA mix (14.0%), both significantly lower than the control group (37.3%). GWS showed slight mass loss reductions at lower temperatures, and the increases in CWA content delivered maximum reduction during exposure over 350°C. UPV results confirmed that GWS and CWA modified internal structure; influence of CWA was temperature‐ and dosage‐dependent with indication of integrity retention at appropriate limits. At ambient conditions, based on UPV criteria all CWA–10% GWS concretes were classified as “excellent” quality. Results from a response surface methodology (RSM) framework found an optimal mix that maximized compressive strength and UPV at the same time as minimizing mass loss, showing one feasible route to thermally resistant resource‐efficient concrete which upcycles solid wastes. A simplified environmental assessment also confirmed a reduction in carbon dioxide emissions per cubic meter, supporting a lower carbon footprint and more sustainable construction.