Influence of type and dosage of micro-fibres on the physical properties of fibre reinforced mortar matrixes

An experimental study is herein presented focusing the physical properties of fibre-reinforced mortar. A reference mortar mixture was adopted and three different types of reinforcement with micro fibres (steel, polypropylene and glass) were adopted, adding different volumetric dosages, ranging from 0.5% to 2%, in 0.5% increments. The influence of each type of fibre and dosage on the properties of the mixture, including workability, density, porosity, and Young’s modulus was analysed. In summary, it was observed that the workability was extremely reduced for polypropylene and glass fibres. It was found that this parameter has an important role in terms of porosity and bulk density. The latter property decreased until 8% when polypropylene or glass fibres were added to the reference mixture. However, the porosity was significantly higher for mixtures with those fibres, with values reaching nearly twice the porosity of the reference mixture. The dynamic Young’s modulus was not highly sensitive to the presence of steel fibres, with a reduction lower than 5% in all tested dosages. In the case of mixtures reinforced with polypropylene fibres and glass fibres, this reduction has reached at most 16% and 13%, respectively. This effect was even higher for the static Young’s modulus, experiencing a maximum reduction of 32%, for a 0.5% dosage of polypropylene fibres.FCT PTDC/ECM/119214/2010, FCT SFRH/BD/84355/2012, DE15010170