Experimental investigation of a sustainable reinforced cantilever concrete slab exposed to different intensity of temperatures

Recently, several scientists have paid special attention to how high temperatures alter the chemical and physical features of reinforced concrete structural members such as slabs. Cantilever concrete slabs, the impact of cooling regimes, the influence of the crack created during heating, and the residual strength of concrete slabs subjected to extreme temperatures were very limitedly investigated in the reviewed literature. Therefore, this research investigated the behavior of cantilever concrete slabs subjected to elevated temperatures and cooling regimes. Two different slab thicknesses (100 mm and 150 mm), various intensity of temperature (200 °C, 300 °C, 400 °C and 500 °C) and two different cooling conditions (Air and Quench cooling) were examined. The observations made during the thermal loadings were the moisture movement, deformation, crack patterns, and temperature on the slab's exposed (bottom) and unexposed surface (top). The results indicated that the magnitude of temperature influences all the tested specimens. In the quench-cooled condition, the development of cracks was increased in the non-exposed slab surface when heated at 300 °C, 400 °C and 500 °C. The severity of the exposed temperature and cooling regimes also affected the concrete slab's irreversible loss of flexural stiffness. The flexural stiffness reduction of the 100 mm thick slab varied from 1.68% to 35.52% for a temperature range of 200 °C–500 °C under air-cooled conditions, while for the quench-cooled specimens, the stiffness reduction varied between 0.88% and 45.92% for the same temperature range. On the other hand, increasing the slab thickness from 100 to 150 mm decreased the stiffness reduction, where the stiffness reduced by 1.02%–24.61% and 0.28%–32.17% for the cases of air and water coolings, respectively.