Polypropylene fibres (PP) have been used mainly in non-structural applications for limiting crack width due to shrinkage effects of cement-based materials. Being insusceptible to corrosion, PP fibres can also be regarded as viable discrete reinforcement elements for the production of thin concrete elements. The relatively low elasticity modulus, tensile strength and almost frictional-based reinforcing nature of PP fibres have been pointed out as the main arguments for preventing their use in structural applications, as a total or even partial replacement of conventional steel reinforcements. However, significant improvements have been made, not only on the material properties of PP fibres, but also on their surface treatment, that provide the means to develop fibre reinforced concrete (FRC) with toughness levels capable of being used for structural applications, according to the requirements of fib Model Code 2010. To have a comprehensive assessment of the potentialities of this type of PP fibres for structural applications, currently designated as PP structural fibres, this work presents the development of an integrated experimental and numerical methodology. The experimental program is composed of fibre pull-out tests for deriving the local bond-law of the PP fibres, considering the influence of the fibre orientation. It also includes three-point notched beam bending tests for deriving the toughness class of the developed FRC, and to provide, by inverse analysis, the stress crack width constitutive law of this FRC. Regarding the numerical strategy, a model was developed for determining the moment-rotation relationship of FRC considering the fibre pull-out constitutive laws, fibre orientation profile and fibre distribution.
The predictive performance of this model is assessed by using available experimental results, and adopted for exploring the potentialities of the developed FRC for structural applications by executing parametric studies.
Valente, T.; de Sousa, C.; Costa, I.; Melo, F.; Barros, J., “Integrated model for predicting the flexural capacity of concrete elements reinforced with non-corrodible discrete reinforcements”, RILEM-SC: 3rd RILEM Spring Convention 2020, Guimarães, Portugal, 10-14 March 2020.