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.”
These bombs are not just dead weights. These bunker busters are equipped with precision guidance and fly to and hit a person on the head if they desired. It's also designed to deliver a huge explosion AFTER it penetrates with the kinetic impact.
It can also be set to explode right before impact, like Israel really likes to do when attaching residential high-rises, to deliver maximum destruction and death.