In this study effect of pressure application to fresh concrete right after casting and during first 24 hours of hardening is examined. The aim of pressure application is to maximally eliminate pores, remove excess capillary water, and improve density of concrete matrix. In terms of the different effect of pore size on concrete performance, the pores in concrete can be classified as follows: harmless pores (<20 nm), few-harm pores (20–50 nm), harmful pores (50–200 nm) and multi-harm pores (>200 nm). By pressure application it is possible to considerably reduce amount of pores (>20nm), make concrete matrix denser and significantly increase compressive strength. Concrete was cast in specially designed cylindrical mould, with possibility to apply pressure. In this study pressure of 0 – 50 MPa was applied. Cylindrical samples with diameter of 50 mm and diameter to height ratio 1:2 were prepared. High performance mixes, incorporating microsilica and nanosilica particles were prepared.