MODERATE-STRENGTH CONCRETE REINFORCED WITH POLYOLEFIN FIBRES: CONSIDERATIONS AND DESIGN OF A COMPETITIVE STRUCTURAL CONCRETE

Abstract

Polyolefin fibre reinforced concrete (PFRC) has become an attractive alternative to steel fibre reinforced concrete for structural applications. Although PFRC has shown capacity for meeting the structural requirements set in the regulations sometimes, complying with the residual strength value at 0,5mm of crack opening (fR1) might be a challenge. That value is aimed at avoiding brittleness of the concrete element and in certain occasions require fibre dosages close to 6kg/m³. Most of the previous studies have been performed with normal or high quality concretes and consequently their strength at the end of the limit of proportionality (fLOP) is also remarkable. Given that the residual strength at fR1 is proportional to fLOP, manufacturing of a concrete with inferior mechanical properties would allow production of one that encountered fewer issues related with brittleness and offered improvement in tensile and flexural strength at a reduced cost. In this study, several concretes with reduced mechanical properties and with 6 and 7,5kg/m³ of polyolefin fibres were manufactured. Their mechanical response was analysed in order to determine if they were apt for their use in low responsibility structural concrete members. Moreover, the influence of the method used to add the fibres was studied by adding the fibres in two different ways adding them individually from sacks or using pucks (50g each one). Keywords: Polyolefin fibre reinforced concrete, regulation requirements, moderate strength concrete.