My dream house (to be built) has these walls and my friend thinks that they're penetrable by something other than a military-grade ground penetrating bomb. Is this true or is he full of ****? Might also be useful to know that I'm putting the time setting in a zombie apocalypse where grenades are holy grails and not even the military has any C4 left.
cosmic rays will go right through , neutrons,neutrinos, all sorts of stuff.
A bulldozer or wrecking ball could go through it with some effort, but not much other than those. But have you thought about how heavy the structure will be and what type of foundation system will be needed? Also, concrete has zero insulation value so beyond the cost of all this concrete, you will need to either remote wall the insulation (foam panels) or build a secondary wall for insulation. And you better plan all the doors and windows carefully because it would extremely difficult if not virtually impossible to make any changes later on.
