Steel fiber reinforced concrete characterization based on a magnetic probe

Steel fiber reinforced concrete (SFRC) is a composite material which is becoming more and more widely employed in building construction, due to its improved resistance to cracking and crack propagation with respect to plain concrete. Its mechanical behavior strongly depends on the choice of the properties of the fibers and their volume fraction in the concrete mixture. As any material employed in building construction, testing the material “on the site” represents a very important task. Very often this requires employing non invasive and non destructive measurement methods which have to be implemented directly in-situ. In this paper a new method for the detection of fiber density and orientation is presented. It is based on the employment of a probe sensitive to the magnetic properties of the steel fibers. The performances of the method have been theoretically and experimentally analyzed as well as a comparison with the results obtained with a previously developed capacitive method is also presented.