Numerical and experimental analysis of fatigue-induced changes in ultra-high performance concrete

Abstract

This contribution deals with experimental and numerical results on the fatigue behavior of Ultra-High Performance Concrete (UHPC). In order to characterize fatigue-induced changes in detail, UHPC samples were examined using scanning and transmission electron microscopy (SEM and TEM). It could be shown that a densification of the binder matrix occurs caused by a transformation of nanoscale ettringite, and the content of unhydrated cement clinker influences the fatigue resistance of UHPC. For numerical investigations of the mechanical behavior of UHPC, the Bonded-Particle Model (BPM) has been used and calibrated with experimental data. The mesoscopic BPM model consists of three phases: Matrix, ITZ (Interfacial Transition Zone), and aggregate. A newly derived rheological fatigue formulation for binder and ITZ bonds was developed to apply small scale-changes and plastic deformations to reproduce the correct fatigue behavior.