Mechanical and micro‐characterization of alkali‐activated concrete under high‐temperature exposure

Abstract In the event of a fire, the performance of concrete becomes pivotal for structural integrity. Concrete undergoes significant changes in its mechanical properties when exposed to high temperatures. This study investigates the mechanical and micro‐characterization of concrete incorporating ground granulated blast furnace slag (GGBFS) under ambient and exposed conditions. The study examines alkali‐activated concrete (AAC) by implementing sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ) as alkali activators. Three different fractions of GGBFS and alkali activators (AAs) were employed in the concrete mixes. The mechanical properties of the AAC were evaluated under ambient and elevated temperatures, and the results were compared with those of Portland slag cement (PSC). The study's findings indicate that AAC outperforms PSC, and the study recommends using 93% GGBFS with 7% AAs as a suitable replacement for PSC. The mechanical properties of AAC are enhanced by 20%–47% at ambient conditions. The strength loss for the AAC with increased temperature is also less than that of the PSC concrete.