Numerical Simulation of Concrete Beams Reinforced with Mixed Recycled/Industrial Steel Fibers

Abstract

The disposal of waste tyres represents a big issue in waste management and, then, several recycling procedures have been investigated and in the last decade. One of them consists of partially replacing “natural” constituents of concrete (i.e., aggregates and fibers) with recycled ones derived by waste tyres (e.g., rubber particles in concretes and recycled steel reinforcements), in view of the twofold objective of reducing both the demand of raw materials and the amount of waste to be disposed in landfills. Therefore, a research study is proposed herein to investigate the mechanical behaviour of concrete reinforced with Recycled Steel Fibers (RSFs) recovered from waste tyres. Particularly, the results of an experimental activity carried out on Fiber-Reinforced Concrete (FRC) obtained by mixing Industrial Steel Fibers (ISFs) and RSFs are briefly presented. The structural behaviour of FRC beams in bending has been evaluated in terms of traction-separation law and the possible synergy/replaceability of both fiber types has been investigated. A non-linear cracked hinge model is also presented through an appropriate fracture-based formulation, with the aim of simulating the crack-bridging mechanisms of steel fibers. Then, comparisons between experimental results and numerical predictions are discussed. Both the experimental analysis and the theoretical formulation proposed in this work stem out from the European Project “EnCoRe” (FP7-PEOPLE-2011-IRSES n. 295283; www.encore-fp7.unisa.it) funded by the European Union as part of the Seventh Framework Programme.