A MICROWAVE PROBE FOR THE NON-DESTRUCTIVE DETERMINATION OF THE STEEL FIBER CONTENT IN CONCRETE SLABS

摘要

A non-destructive measuring technique to determine the fiber content in hardened steel fiber reinforced concrete is presented. The technique is based on an accurate open-ended coaxial probe reflectometry method for measuring the effective permittivity of the fiber reinforced concrete and on a mixing rule from the classical homogenization theory for deriving the fiber content from the measured permittivity. A microwave probe has been constructed. Experimental results for reinforced concrete slabs with various fiber contents confirm the potential interest of this technique.