Are you referring to sulfur as an admixture or molten sulfur "concrete", a mixture of sulfur and flyash that is used for leveling and for a capping compound for testing concrete specimens?

Sulfur was tried numerous times as an admixture in both PCC and asphaltic concrete with various results, none of which seemed to be commercially viable. It has to be heated into a fluid mix and hardened to achieve anything like the strengths you referenced, which makes it impractical to use in a mixture with PCC.

Can be used as a leveling medium, but you have to remember that it leaches and the leachate can be highly acidic, thus creating corrosion problems.

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Sulfur Concrete indeed can exceed 9000 psi compressive strengths.  I am currently working on a project in Central Asia for utilizing SC as a road surface.  Basically, SC is a thermoplastic material so it is mixed and applied more like asphalt, although it is poured and finished like regular concrete.  The composition is about 10-12% sulfur, 86-88% aggregate, and 2% modifier.  The whole trick is to add a "modifier" to this material (about 2%) to keep it from becoming brittle.  The mixture is kept at 125-141C during mixing and pouring.  It attains nearly full strength within 24 hours.  Currently the best uses include chemical resistant floors (as the chemical resistance of SC is far superior to normal concrete).  If you want more information let me know.