This paper presents the results of an experimental study aim for enhancing the understanding of some characteristics of an interior explosion within a confined underground area, as well as the effect of the explosive charge size on the pressure distribution along the compacted specimen which is placed in the mold of Underground Explosion Pressing apparatus. The study involved blast test which providing a measured pressure based on the amount of explosive used. The type of explosive used for this experiment is Emulex with detonation velocity range from 4500m/s to 5700m/s. The microstructure of specimen is analyzed using Scanning Electron Microscope (SEM). Then, the hardness of both specimens is tested using Rockwell Digital Hardness and the result for specimen hardness is 50.7HRA.
