UHPFRC early age time dependent response - experimental characterization and numerical analysis

Thin ultra high performance fibre reinforced concretes overlays are suitable for rehabilitation of structures thanks to their enhanced properties. However, in such composite structures, restrained differential shrinkage cracking is an important concern. To investigate this problem a test set-up, inspired by previous research, was developed. The set-up simulates real restraint and thermal conditions commonly encountered in composite members. An analysis was first performed to identify the adapted configuration of the set-up from the point of view of geometry and cooling system, using a finite element program for time dependent behaviour of multilayer systems developed by (Femmasse 2007). The predicted temperatures and displacements are in reasonable concordance with measurements. The test results showed that the proposed set- up and the testing procedure are a practical and efficient approach for investigating the early age UHPFRC behaviour especially the evolution of the internal stresses, the autogenous shrinkage and the thermal effects.