Abstracts:Abstract Residual prominences of concrete are of specific concern, as exposure to elevated temperatures adversely influences its characteristics. The current study strives to develop heat-resistant sustainable concrete by incorporating recycled refractory brick as an alternative to typical fine aggregate considering ordinary portland cement as binder material. Eight distinct concrete blends have been prepared starting from 10% to 100% replacement levels and subsequently exposed to 200, 400, 600, 800, 1,000, and 1,200°C temperatures. A mass loss of 0.36%–8.76% and density loss of 0.4%–11.73% were observed as the temperature rises from 200 to 1,200°C. 6.05%, 23.16%, 43.53%, 70.90%, 82.83%, and 90.73% reduction in ultrasonic pulse velocity values and 13.21%, 40.72%, 67.80%, 91.68%, 97.05%, and 99.11% increments in damage degree have been noticed upon exposure to the identical temperature regimes, respectively. 98.1%, 74.8%, 35.9%, 13.5%, 3.3%, and 2.4% dynamic modulus of elasticity values have been retained by the samples upon submission to identical temperatures. The outcomes indicate the formation and development of surface cracks and internal cracks with the growth in temperature. The compressive strength has an improvement of up to 28% for the specimens with 20% fine aggregate replacement with RRB at 200°C, 63% for both 20% and 30% replacement at 400°C. Similarly, the same trend of improvement existed in compressive strength by 53% for the specimens with 30% fine aggregate replacement with RRB at 600°C, elucidating improved ceramic bonding due to the incorporation of recycled refractory brick aggregates. Additionally, it was found that a higher amount of recycled refractory brick (50%–100% replacement levels) rather than typical fine aggregate considerably reduces the density and weight losses at higher temperatures. In the authors’ opinion, the concrete specimens with 10%–30% replacements may be considered as promising and potential concrete blends for diverse practical applications under the scope of the present investigation.