Previously, a yield strength of 5,000 pounds per square inch (psi) was enough for concrete to be rated as “high strength,” with the best going up to 10,000 psi. The new UHPC can withstand 40,000 psi or more.
The greater strength is achieved by turning concrete into a composite material with the addition of steel or other fibers. These fibers hold the concrete together and prevent cracks from spreading throughout it, negating the brittleness. “Instead of getting a few large cracks in a concrete panel, you get lots of smaller cracks,” says Barnett. “The fibers give it more fracture energy.”
You triggered a thought: what if those bunker busters carried a payload of corrosive material, something that the explosive event could deeply embed into the concrete, slowly degrading its strength - possibly until total failure?
What material would that be? Corrosives have limits, they can’t just keep dissolving stuff forever.
And what would “total failure” look like? It’s a mountain, it’s not going to just collapse into goo.
Blood of xenomorphs from the Alien movies
That’s a work of fiction. You might as well suggest dropping lightsabres on the bunker.
Thus, the explosive assist for initial penetration. The type would depend on the composition of the concrete, you’d probably be more successful targeting the tension strength of the fibers or metals instead of the compression strength of the cement.
You don’t need goo, you just need enough weakening that it no longer supports the 250’ of loose rubble atop it and collapses into the interior space.
Coreium.
We drop an overloading nuclear reactor on top of the complex, and let the radioactive core China-Syndrome itself straight through, rendering the entire area uninhabitable for thousands of years.
My first thought is actually getting the corrosive substance onto enough of the concrete would be difficult, assuming they aren’t able to penetrate the concrete then they have to rely on it seeping from the ground, or if they can penetrate then the substance is only really going to be in the chamber where the buster detonated.
I have zero experience with ordnance or busting bunkers though so that’s just a shot in the dark
Yeah, if the concrete is 40’ thick and they’re only getting 10’ of penetration with the explosives, then this isn’t going to do much. But if it’s 20’ thick and they got through the first 12 with HE, the remaining 8 are going to have a lot of cracks to admit slow liquid death.
I have zero information on what the reinforcers are in the concrete, so shot in the dark is about right. Glass might be tough - unless you could deliver hydrofluoric acid effectively. Metals - we’re not going to want to wait for iron to oxidize, looks like hydrogen embrittlement with HF again - so maybe that’s the magic sauce. Nasty stuff, but that’s what weapons manufacturers are good at handling and packaging: nasty stuff.
2000 lbs of HF poured on the surface isn’t going to do much to the buried chamber, but 2000 lbs of HF delivered into the freshly stressed and heavily cracked concrete layer under all the dirt - that could be a problem for future use of the facility.
Unfortunately (?) HF is a gas.
inste-edit: I know I’m being pedantic and a reasonable concentration of hydroflouric acid is what you were talking about. There was an article somewhere about a 1 tonne spill on chlorine triflouride