In an ongoing research project, the effects of vibrations on young (reinforced) concrete are being investigated. Such a situation is often encountered at repair and widening works on bridges at the time when parts of newly cast concrete are connected to the existing bridge under running traffic. In the research project, a systematic approach is pursued to investigate the influence of different kinds of vibrations (harmonic, transient/"real"; intermittent, continuous), durations of vibration, concrete mixtures, and construction types (plain concrete, reinforced concrete, direct contact of concrete surfaces). The quality of the shaken test specimens (and respective reference specimens) is determined in terms of strength, density, elastic modulus, cracks, homogeneity, and permeability. Preliminary results indicate that plain concrete does not suffer deteriorations of strength or stiffness when excited by traffic vibrations, in general. However, the bond between concrete and rebar may not evolve properly.