| Summary: | The object of the study was the cement phase C-S-H – X-ray amorphous calcium hydrosilicates, obtained by steaming at 80°C together limestone and silica at different molar ratios CaO/SiO2 = 0.5; 1.0; 1.5. The contact strength of the C-S-H phase with additions of portlandite, silica and alumina zols, high-aluminate slag was estimated by hyper-pressing method with subsequent destruction. It was established that the contact strength of the cement phase increases in proportion to the specific pressing pressure, the age of samples and inversely the phase basicity reaching 12 MPa. It was evidenced that additives increase the contact strength of the C-S-H stone. The features of the phase formation during the hydration of calcium aluminates were considered. It was established that there is no negative effect of additional porosity on the strength of the stone, because the restructuring of calcium hydroaluminates takes place during hyper-pressing. The specific behavior of low-basic calcium aluminates in a mixture with the C-S-H phase was established in the case of using high-aluminate slag, which consists in additional formation Al(OH)3 gel during the hydration, that is provide an increase in the contact strength of the compositions.
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