Paula Folino

Performance Dependent Failure Criterion for Normal- and High-Strength Concretes

A new approach to describe the maximum strength criterion of concretes with different strength capacities is formulated. The proposed failure criterion incorporates the so-called “performance parameter” ( βP ) that controls the dependence of the maximum strength on the concrete quality. To assure the feasibility of the solution procedure for any possible set of known data, different methods are proposed to determine βP according to the available material data. The performance dependent strength criterion presented in this work is expressed in terms of the Haigh Westergaard stress coordinates and as a function of four material parameters that fully define the compressive and tensile meridians of the failure criterion. The variation of the shear strength between these two meridians follows an earlier elliptic interpolation. The proposal includes approximating functions that define the dependence of the above mentioned four material parameters on the two fundamental mechanical properties of concrete: the uni...

Cementitious Composites Reinforced with Recycled Fibres

Pneumatic tyres are nowadays among the most widespread industrial products and, hence, handling tyres that have reached their end-of-life is indeed a critical issue. This Chapter provides readers with the key facts about tyre production and consumption. Particularly, it describes the raw materials which they are made from, and summarises the main classifications currently accepted worldwide. The typical product life-cycle is shortly outlined before analysing the possibility of recycling waste tyres for producing new products. Relevant properties of concrete reinforced with recycled fibres are presented, with special focus on the post-cracking behaviour of these composite materials. Emphasis is given to the suitability of using recycled fibres obtained from waste tyres as partial or total replacement of industrial steel fibres for obtaining fibre reinforced concrete.

Insights into the Triaxial Behaviour of Recycled Aggregate Concrete

In this chapter, the results of an experimental programme aiming to investigate the incidence of different replacements ratios of natural coarse aggregates by recycled ones on the mechanical behaviour of Recycled Aggregate Concrete (RAC) under tri-axial compression stress states are presented and discussed. The experimental campaign performed at the University of Buenos Aires considers four concrete mixtures including a reference or parent concrete and RACs with 30, 60 and 100% of coarse aggregate replacements. Besides the aforementioned tri-axial compression tests, the results of splitting tensile and uniaxial compression experimental tests are also presented. It is showed that increasing levels of recycled aggregates lead to concretes more sensitive to confinement.

Constitutive Formulations for Concrete with Recycled Aggregates

In this Chapter, a thermodynamically consistent gradient model is proposed for natural aggregate concrete and then, modified to take into account the addition of different contents of recycled aggregates and its influence on concrete mechanical response. A particular and simple form of gradient-based plasticity is considered, where the state variables are the only ones of non-local character. After describing the material formulation for natural and recycled aggregate concretes, the model calibration is performed with experimental data taken from literature. A comprehensive numerical analysis is presented, where the effects of the recycled aggregate content on the performance of concrete in pre and post-peak behavior are evaluated and discussed, for different stress states. Finally, the ability of the model to capture the variation of mechanical response of concrete with different recycled aggregate contents is demonstrated for different mechanical tests.

Hybrid Industrial/Recycled SFRC: Experimental Analysis and Design

This paper is intended as a practice-oriented contribution about the use of sustainable Fiber-Reinforced Concrete (FRC) in the design of structural members according to the provisions of the current codes and guidelines. More specifically, the work focusses on Hybrid Industrial/Recycled Steel Fiber-Reinforced Concrete (HIRSFRC) realised by combining tailored Industrial Steel Fibers (ISFs) with Recycled Steel Fibers (RSFs), the latter being obtained by recycling waste pneumatic tyres. First, the results of a series of experimental tests, carried out for characterising the behaviour of the aforementioned materials, are summarised. They are specifically considered for evaluating the parameters that are generally considered for describing the post-cracking response of FRC. Then, a parametric analysis on the sectional behaviour of beams made of the aforementioned HIRSFRCs is proposed: this is intended at highlighting the influence of the material behaviour on the ultimate bending moment and curvature of structural members.