EFFECT OF INCORPORATING ORGANIC AND STEEL FIBER ON FIRE RESISTANCE OF 80 TO 200N/mm2 HIGH STRENGTH CONCRETE COLUMNS

Fire resistance of High strength reinforced concrete columns with specified design strength of 80N/mm2 to 200N/mm2 were conducted by loaded fire resistance tests. High strength concrete column without fiber showed explosive spalling and fire resisting period of columns were less than 2 hours. Incorporating polypropylene fiber to concrete of 150N/mm2 or less was showned to be effective for preventing spalling of concrete and prolonging fire resisting period. For more than 180N/mm2 columns, 0.33vol% of polypropylene fiber were not sufficient for preventing explosive spalling and incorporating both polypropylene and steel fiber enables to maintain 3 hours of fire resistive period.