Effects of the very low water/cement ratio

The subject of paper are the results of the study on the hardened cement paste prepared with very low w/c ratios from 0.115 till 0.075 and pressure compaction till 300 MPa. Well known and often reported the significant compressive strength increase and the total porosity and pore median decrease was found. But other significant effects have been found: an increase of the CaO:SiO2 and the decrease of H2O:SiO2 ratios, their consequence were the particles morphology changes shown as a gradual loose of the crystal character under the formation of the finer spherical and cylindrical particles of the hydration products showing the increase in the biding capacity and the increase of the homogeneity of the pore structure. These factors seem to be the principle of the extreme effects of the very low w/c ratio and pressure compaction used. In the final consequence the fine-grain character and form and dimension increased homogeneity enabling the formation of the amount of the strength connection among the individual particles into and extraordinary dense structure seem to be the principle effect of the very low w/c ratio and pressure compaction of the cement mixtures.