High strength concrete
The definition of high strength concretes is continually developing. In the 1950s a cube strength of 35MPa was considered high strength, and in the 1960s compressive strengths of up to 50MPa were being used commercially. More recently, compressive strengths approaching 140MPa have been used in cast-in-place buildings. Eurocode 2 allows for concrete strengths of up to 105MPa cube strength. There is no definition of high strength concrete in Eurocode 2, but the measures and formulae change when the concrete strength is greater than C50/60 so this seems a reasonable working definition.
High-strength concrete columns can hold more weight and therefore be made slimmer than regular strength concrete columns, which allows for more usable space, especially in the lower floors of buildings.