Influence of fiber type on the resistance of fibre reinforced concrete to high temperatures

Iako beton spada u grupu anorganskih negorivih materijala, ima nisku toplinsku vodljivost i relativno visoki specifični toplinski kapacitet, u uvjetima požara može doći do eksplozivnog pucanja, te posljedično smanjenja nosivog presjeka armirano-betonskog elementa. Jedna od najučinkovitijih metoda sprečavanja spomenute pojave je dodatak polipropilenskih vlakana u svježu betonsku mješavinu, međutim u posljednjem desetljeću, istražuje se mogućnost dodavanja i drugih vrsta vlakana za istu svrhu. U ovom radu je, temeljem analize dostupne literature uspoređen utjecaj dodatka polipropilenskih, čeličnih i jutenih vlakana te njihove mješavine s ciljem povećanja otpornosti betona na visoke požarne temperature. Za lakše razumijevanje ponašanja betona pod utjecajem visokih temperatura, najprije su objašnjeni mehanizmi razaranja betona i najbitnija svojstva koja utječu na njegovu otpornost. Istraživanja mehaničkih svojstava mikroarmiranih betona, ukazuju na to da dodavanjem više vrsta vlakana (hibrida), poboljšava rezidualna tlačna i vlačna čvrstoća betona u odnosu na betone bez vlakana i betone sa samo jednom vrstom vlakana.Although concrete belongs to the group of inorganic non-combustible materials, have low thermal conductivity and relatively high specific heat capacity, explosive Spaling can occur in fire conditions. Consequently, explosive spalding can reduce the load-bearing cross section. One of the most effective methods to prevent this phenomenon is the addition of polypropylene fibres to the fresh concrete mix. However, in the last decade, the possibility of adding other types of fibres for the same purpose has been studied by various researchers. In this paper, based on an analysis of the available literature, the influence of adding polypropylene, steel and jute fibers and their mixes to increase the resistance of fibre concrete to high fire temperatures is compared. To understand the behaviour of concrete under the fire exposure, the work first explains the mechanisms of destruction and the most important properties that affect its resistance. Research on the mechanical properties of fibre reinforced concrete indicates that adding different types of fibers (hybrids) to concrete can improve the residual compressive and tensile strength compared to plain concrete and concrete with only one type of fibre