EFFECTS OF CONCRETE TYPES, ELEVATED TEMPERATURES, AND DIFFERENT COOLING TECHNIQUE ON CONCRETE COMPRESSIVE STRENGTH

The characteristics of concrete subject to high temperature are fundamental to improve the endurance of the fire of constructions and to come up with detailed statistics for fire design. Throughout and subsequent a fire, various components of a concrete structure experience contrasting heating and cooling situations. Consequently, the residual strength and stiffness characteristics in the concrete composition necessitate being estimated previously, a conclusion can be performed as to whether the structure must be rebuilt or can be repaired. Comparisons between the residual compressive strengths of four different concrete type (normal concrete (N1), high strength concrete (H), ultra-high strength concrete (UH), and steel fiber concrete (N2)) exhibited to different temperatures (25, 100, 200, 400, 600, 800 and 1000 degrees C) cured for 28 days are examined with the impact of three cooling methods to determine their effects on the compressive strength (cooling in the air (gradually), water cooling, and cooling by extinguisher). It was observed that the loss in strength in compression was higher within water cooling than gradually and extinguisher cooling by (59.14% for N1, 58.97% for N2, 57.7% for H, and 56.41% for UH) under (1000 degrees C) compared to (25 degrees C); this is related to the extreme thermal shock causing higher micro cracks leading the concrete to lose more strength. Steel fiber has the ability to resist the rising in temperature caused an enhancement in the compressive strength and less reduction in residual compressive strength after heating. The maximum improvement in residual compressive strength for steel fiber concrete (N2) under (1000 degrees C) were (14.89%) for gradually cooling compared to normal concrete (N1).