Commonly, the design of concrete mix for reinforced structures is based on the definition of consistency (opposition of the material in the fresh state to deformation) and the characteristic compressive strength, considering that the capacity of the tensile behavior is…
Commonly, the design of concrete mix for reinforced structures is based on the definition of consistency (opposition of the material in the fresh state to deformation) and the characteristic compressive strength, considering that the capacity of the tensile behavior is assumed by the steel reinforcement. However, the use of steel fibers as dispersed reinforcement in concrete has led to the development of special documents within structural design codes, lately in date Annex L in the new Eurocode2,definingsteel-fiber reinforced concrete (SFRC) also in flexural strength classes. This fact allows us to consider the fracture behavior of the material, taking into account at the same time its compressive strength and its bending capacity, both in terms of strength, energy absorption capacity, and ductility. Hence the need to develop a SFRC mix design methodology, more adjusted to the real behavior of the composite, which would give rise to more efficient structural elements. In this communication, a new mix design method for SFRC based on its rheological and fracture be- havior is presented. In the fresh state, the target consistency (defined by the rheological parameters of the material) is established. In the hardened state, the target compressive and flexural strength classes are established too, both related through a series of equations obtained using statistical techniques applied to an extensive database of experimental results. From the geometric properties of the fiber (length, diameter and aspect ratio), the volume fraction of steel fiber required to reach the target flexu- ral strength classes is calculated through these equations. Finally, the optimization of the compactness of the composition of the granular skeleton is carried out, which influences the modulus of elasticity and the compressive strength. The results of the experimental validation of the methodology carried out on a laboratory and industrial scale show its relevance and indicate its suitability for the design of SFRCstructural elements, which is an added value in concrete technology. 1 ´ A. De La Rosa, G. Ruiz, V. W. Masih and R.