This dataset contains synthetic ultrasonic SH-wave measurements generated using finite-difference modelling for a concrete specimen with a void. The synthetic model is based on a real laboratory specimen manufactured in 2025 at the Bundesanstalt für Materialforschung und -prüfung (BAM). The specimen dimensions are 1.0 m × 0.3 m × 0.6 m. A cylindrical void (diameter 7.5 cm) is located 15.5 cm below the top surface. The numerical model represents the front face of the specimen with a grid size of 0.000625 m. The concrete is assumed homogeneous with shear-wave velocity V_SH = 2700 m/s and density ρ = 2400 kg/m³. The acquisition geometry represents an ultrasonic scanner system with dry-point SH transducers. The dataset consists of 35 sources and up to 64 receivers per source. Source spacing is 2 cm, receiver spacing is 1 cm, and the minimum offset is 5 cm. The source signal is a Ricker wavelet with a central frequency of 50 kHz. The time step is 5×10⁻⁸ s and the recording length is 0.00045 s. The dataset includes 35 synthetic shot gathers stored in SU format. The wavefield contains direct waves, reflections from the void, back-wall reflections, and partially multiple reflections.