The Impact of the Amount and Length of Fibrillated Polypropylene Fibres on the Properties of HPC Exposed to High Temperature / Wpływ Ilosci I Długosci Fibrylowanych Włókien Polipropylenowych Na Własciwosci Hpc Poddanego Działaniu Wysokiej Temperatury

This paper presents the results of research on high performance concretes (HPC) modified by the addition of polypropylene fibres (PP fibres). The scope of the research was the measurement of the residual transport properties of heated and recooled concretes: gas permeability and surface water absorption. Seven types of concrete modified with fibrillated PP fibres were tested. Three lengths: 6, 12 and 19 mm and three amounts of fibres: 0, 0.9 and 1.8 kg/m³ were used. The research programme was designed to determine which length of fibres, used in which minimum amount, will, after the fibres melt, permit the development of a connected network and pathway for gases and liquids.