[gandalftb]

Nothing secret about Fibercrete:

http://www.superior-industries.com/tech_data_page_297.html

All you need is a good source of silica sand, like a desert...

Fiberglass also makes concrete flexible so it gives instead of cracking. The trick is to layer it with blacktop layers and it becomes a laminate like a compound bow.

Dog-gone-it, Iran’s been spying on Home Depot.

[St_Thomas_Aquinas]

-——Fiberglass also makes concrete flexible so it gives instead of cracking. The trick is to layer it with blacktop layers and it becomes a laminate like a compound bow.———

Makes sense.

Is it even remotely possible that Israel puts troops on the ground? It seems like a ground force will be necessary. They could have smuggled in soldiers and armaments over the past decade....

OK, everyone’s entitled to some wild speculation.

[cherokee1]

Well, Yeah, and then there was Churchill’s sawdust and ice aircraft carrier. The combo really absorbed shock and was cheap to fix———maybe Persians will freeze an iceberg over their digs. It’s fun to remember how most of the damage was done to Hitler’s big blockhouses on the Atlantic wall-——not by blasting them directly but by blasting the beach out from under them and watching them collapse into the surf-—————

[Paul R.]

I'm no expert, but there's even more to it than that. The bunker busters work by setting off rapid successive charges that essentially bore down to the bunker. Sort of like a jackhammer. Someone who builds bunker buster resistant bunkers for US has told me that layers of various densities, hardness and orientation are used not so much for resilience and strength, as to cause the bunker buster to veer off course, as it bores in.

That said, cratering effects are at work, and essentially the solution to a bunker too deep to get to is to keep hitting it. But that's where the limited number of MOP's, and their cost, comes into play. Still, per Heinlein:

"Man, I don't think we had better hit that mountain again."

"Why not, Mike?"

"It's not there any longer."

Now, if we had listened to Heinlein regarding space policy, Iran's bunkers would be a relatively easy problem to solve. We could, literally, "throw rocks at them." And they could not stop us.