Modelling the influence of age of steel fibre reinforced self-compacting concrete on its compressive behaviour

Steel fibre reinforced self-compacting concrete (SFRSCC) can combine the benefits of self-consolidating concrete technology with those derived from adding steel fibres to quasi-brittle cement based materials. In a recent applied research project joining pre-casting industry, private and public research institutions, a method was developed to design cost-competitive SFRSCC of rheological and mechanical properties required for the prefabrication of SFRSCC fac¸ade panels. To assure safe demoulding process of the panels, the influence of the concrete age on the compression behaviour of the SFRSCC should be known. For this purpose, series of tests with specimens of 12 h to 28 days were tested in order to analyze the age influence on the compressive strength, strain at peak stress, Young’s modulus, and compressive volumetric fracture energy. The experimental program was divided in two groups of test series, one with SFRSCC of a volumetric fibre percentage of 0.38% and the other with 0.57%. To apply the obtained data in the design and numerical analysis framework, the influence of the age on these SFRSCC properties was modelled. This work describes the carried out experimental program, presents and analyzes the obtained results, and provides the derived analytical expressions. The study reported in this paper is part of the research program “Prefabricated sandwich steel fibre reinforced panels” supported by FEDER and MCT, and promoted by ADI (the funds were 45% of the applied amount). This project involves the Companies PREGAIA and CIVITEST, and the University of Minho. The authors wish to acknowledge the materials generously supplied by Bekaert (fibers), SECIL (cement), Degussa (superplasticizer), and Comital (limestone filler). The first author wishes also to acknowledge the grant SFRH/BD/18002/2004, provided by FCT.