In 2012, the Pentagon requested $82 million to develop greater penetration power for the existing weapon. A 2013 report stated that the development had been a success, and B-2 integration testing began that year.
The bomb can penetrate 200 feet of 5000 psi hardened concrete and is accurate enough for multiple hits on the same location to penetrate deeper targets or targets with even stronger concrete. One GBUJ-57A/B can only penetrate 8 meters of 10,000 psi rock or concrete. This could drop to 2 meters of 30,000 psi material.
Rock of over 10,000 psi is considered hard. The strongest granite is about 30,000 psi. In 2007, the University of Tehran made several concrete cubes between 50,000 to 60,000 psi, and possible stronger. The aggregate to be made from quartz, and had some steel fibers in the mix.
High-strength concrete has a compressive strength greater than 40 MPa (5800 psi).
Ultra-high-performance concrete is a new type of concrete that is being developed by agencies concerned with infrastructure protection. UHPC is characterized by being a steel fibre-reinforced cement composite material with compressive strengths in excess of 150 MPa (21750 psi), up to and possibly exceeding 250 MPa (36250 psi). UHPC is also characterized by its constituent material make-up: typically fine-grained sand, silica fume, small steel fibers, and special blends of high-strength Portland cement. Note that there is no large aggregate. The current types in production (Ductal, Taktl, etc.) differ from normal concrete in compression by their strain hardening, followed by sudden brittle failure. Ongoing research into UHPC failure via tensile and shear failure is being conducted by multiple government agencies and universities around the world.
Micro-reinforced ultra-high-performance concrete is the next generation of UHPC. In addition to high compressive strength, durability and abrasion resistance of UHPC, micro-reinforced UHPC is characterized by extreme ductility, energy absorption and resistance to chemicals, water and temperature. The continuous, multi-layered, three dimensional micro-steel mesh exceeds UHPC in durability, ductility and strength. The performance of the discontinuous and scattered fibers in UHPC is relatively unpredictable. Micro-reinforced UHPC is used in blast, ballistic and earthquake resistant construction, structural and architectural overlays, and complex facades.
Ducon was the early developer of micro-reinforced UHPC, which has been used in the construction of new World Trade Center in New York
DUCON® Micro-Reinforced Concrete Systems is an innovative, high-performance strengthening and force protection system designed for extreme load resistance and energy absorption. DUCON® combines an infuseable ultra high-performance grout with a densely layered MicroMat® steel reinforcement system. The highly-engineered and test-proven system can be custom-designed to a project’s specific performance requirements.
Placement characteristics similar to concrete, combined with the ductility and energy absorption properties of steel, give DUCON® “moldable, steel-like” characteristics.
Like concrete in placement versatility, DUCON® can be applied to new and existing structural members, or prefabricated off-site to create a wide range of precast shapes and sizes.
Like steel with its ductility and energy dissipating qualities, the DUCON® system allows for the highest level of performance for the most challenging applications.
One World Trade Center in New York rests on a 20 story, bombproof foundation that reaches 60 meters underground. Overall, at points within the building where safety is especially critical, several thousand square meters of safety concrete have been used to shore up the construction.
One World trade center cost $3.9 billion.
Reinforcing any bunker in Iran with a lot of micro reinforced UHPC would cost billions. They would have to excavate the already hard rock that is there and replace it with any new superconcrete.
On 25 June 2010, USAF Lt. Gen. Philip M. Breedlove said that the Next-generation Penetrator Munition should be about a third the size of the Massive Ordnance Penetrator so it could be carried by affordable aircraft. In December 2010, the USAF had a Broad Agency Announcement (BAA) for the Next Generation Penetrator (NGP).
Global Strike Command has indicated that one of the objectives for the Next-Generation Bomber is for it to carry a weapon with the effects of the Massive Ordnance Penetrator. This would either be with the same weapon or a smaller weapon that uses rocket power to reach sufficient speed to match the penetrating power of the larger weapon.
SOURCES- Wikipedia, Structural Technologies, Wall Street Journal