Estimation of strength of conventional concrete and concrete with blast furnace slag under elevated temperatures

Concrete which is a mixture of cement, fine aggregates, course aggregate and water, therefore concrete is very strong in nature. Fire can be occurs in any buildings or structures at any time. During fire, materials which are combustible can burn. During fire happen in any building or structures, room temperature will go increasing with respect to time. According to some literatures, room temperature will reaches above 1000°C after 1 hour. Concrete will not catch fire during fire, but due to time dependent, concrete loos its strength at elevated temperatures. This research work is an experimental estimation of strength of conventional concrete and concrete with blast furnace slag as partially replacement of course aggregates by 20 %, 40 % and 60 % by weight with addition of 1 % steel fibers (volume of concrete). All samples was subjected to elevated temperatures ranging from 200°C to 1000°C for 1.0 hours of constant heating and was tested after 0.5 hours, 1 hours and 1.5 hours ( natural cooling). After analysis it was found that the strength of concrete reduces at elevated temperatures, but the strength of concrete with 20 % partially replacement of course aggregates by blast furnace slag shows better results as compared with conventional concrete and other combinations.