Properties of fibre reinforced concrete after various degrees of heatloading
ABSTRACT: The article examines the behaviour of fiber reinforced concrete with polypropylene fibers after exposure to higher temperatures. Testing samples were from concrete with polypropylene fiber reinforcement which is recommended as protection of concrete structures against fire. The samples were heated up in accordance with different thermal curves to the gradual increase to the final temperature. New porous structure of concrete enables escape of expanded water vapour from the cement matrix without considerable damage of concrete microstructure. Microscopy and macroscopy variations, i.e. physic-mechanical properties, of the testing samples were observed after heating and the results were compared with referential concrete, which was not heated. PP fibers of samples exposed to 150°C burned out only at the surface, fibers deep in the sample were only partially deformed by higher temperature. No micro-cracks or any other damage of cement matrix or aggregate was observed on any of tested samples (from 20°C to 250°C).