critical infrastructures protection evaluation when exposed to terroristic or accidental blast wave propagation represents a core topic of research for the French public institute IrSN and the French-german military research institute ISl. The Institute for radiological Protection and Nuclear Safety (IrSN) and the French-german research Institute of Saint louis (ISl) actively cooperate on the evaluation of pressure effects generated by blast wave propagating in hemispherical geometry. During the past few years, IrSN developed a significant experience on hemispherical blast effect assessment using 42g reference hexomax® charges detonated in contact to a planar surface equipped with different types of pressure sensors (piezo-electric and piezo-resistive). based on this experience, ISl developed an outdoor blast-pad located at its own explosive range: 400g TNT equivalent charges are detonated in a factor 2 up-scaled version of IrSN test configuration. Similar sensors are flush-mounted inside a metallic rail integrated below the concrete pad surface. The objective of this joint work is to improve the knowledge on scaling laws for small plastic explosive charges (Semtex, c4 and hexomax®) and their corresponding TNT equivalencies. To achieve this goal, TNT charges were produced at ISl in order to provide a direct, realistic and reproducible reference at the corresponding scale. In addition, the influence of the pressure gauge technology on the blast characteristics was studied and a methodology was developed to minimize this influence and provide guidelines for results comparison between research institutes. Finally, the pressure profiles were also analysed taking into account the fine structure of the shock interacting with the blast pad surface using high-speed imaging. © 2019 WIT Press.