ABSTRACT
ABSTRACT: The addition of an Ultra-High Performance Fibre Reinforced cement-based Composite (UHPFRC) layer has shown to be an effective way of strengthening and significantly improve the durability of existing reinforced concrete structures. In the absence of reinforcement in the new layer, the mechanical behaviour of the material and the performance of the strengthened structural elements significantly depend on the fibre dispersion and orientation with respect to the stress directions. In the present paper, a non-destructive method for the detection of fibre content and orientation in a cast-in-place UHPFRC layer is presented based on the magnetic properties of the steel fibres. The performance of the method has been tested on small UHPFRC specimens, produced with varying fibre content and orientation, and on UHPFRC layers, with and without steel rebars, cast on reinforced concrete slabs. The potential of this non-destructive method for quality control is illustrated by a field application on a 2.1-km long highway-viaduct, in Switzerland.
