Permeability of concrete to water depends on a number of factors. The actual micro-structure of cement paste, and consequently also the number and size of pores in the paste have a major impact on it. Aggregate type used in concrete making also affects the depth of pressurized water penetration into the concrete. The influence of various types of crushed mineral aggregates (basalt, limestone, diabase and andesite) on the concrete pressurized water absorption in comparison to the benchmark concrete produced with river aggregate was studied. The porosity of hardened concrete cement matrix has been examined by the Krüss optical stereo-zoom microscope and adequate software. The share of the pores smaller than ≤1μm in the hardened cement paste decreases with the increase of water-cement factor. On the other hand, the share of the pores larger than ≥10μm increases with the increase of water/cement factor.