An assembly for protecting against explosions and explosive devices is formed with aerogels and frangible components. The basic configuration forms a space between an object to be protected by an aerogel having a frangible backing layer. Such assemblies may be mounted on vehicles and structures, and alternatively used as barriers without attachment to other objects. Different geometries for the rear surface of the assemblies enhance the ability of deflecting gas produced by explosions away from objects to be protected. Flowable attenuating media may be introduced into the space behind the aerogel and in gratings placed in the front of assemblies in order to increase blast energy dissipation in intense blast conditions. Armor components may be added to the rear surface to protect against fragments and projectiles. Aerogels, metal foams, and dense ceramic beads may be incorporated to enhance protection against explosively-formed penetrators and other projectiles.