BEHAVIOUR OF STRESSED AND UNSTRESSED CONCRETE WITH AND WITHOUT POLYPROPYLENE FIBRES AT HIGH TEMPERATURES

摘要

This paper presents the results of an experimental study to compare the influence of polypropylene fibres (f-PP) on the behaviour of high strength concrete (HSC) subjected to elevated temperatures in stressed or stress-free hot conditions.Very few studies are available in the literature on the behaviour of HSC containing PP fibres subjected to stressed or stress-free state with simultaneous application of elevated temperature (tested hot).One group of concrete specimens was subjected to an initial preload of 40 ％ of the initial room temperature compressive strength during the heating (stressed hot), while a second group was in a non-loaded condition during heating (stress-free hot).Results show the stressed concrete had a lower thermal gradient, a decrease in relative porosity when PP fibres were added and an improved compressive strength with or without fibres as compared to the stress-free HSC.