Technology of high efficiency concrete provides for use of ultra-fine micro and nano-sized admixtures which considerably improve properties of fresh and hardened concrete. In the frame of this study the concept of high efficiency concrete provides for two basic directions: 1. Creating ecologically effective concrete mixes with low cement content (<330 kg/m3) for conventional application (mass concrete etc). 2. Creating concrete having high compressive strength (>100MPa) and high performance characteristics allowing producing thin light-weight bearing elements. (HPC –High Performance Concrete, UHPC –Ultra High Performance Concrete). The basic principles for obtaining high performance properties are low water/cement ratio and dense micro structural packing achieved by using special pozzolanic admixtures which chemically react with calcium hydroxide and form calcium silicate-hydrate. Silica fume is the most popular commercially available pozzolanic micro filler based on silicium dioxide. Pyrogenic silica having nano-sized particles (<100 nm), has been elaborated recently.