THE USE OF ALUMINOSILICATE ADDITIVES FOR HARDENING FINE-GRAINED CONCRETE

The article considers the possibility of increasing the strength of fine-grained concrete by introducing an aluminosilicate additive of metakaolin. As a binder, CEM I 42.5-N port-land cements from manufacturers «Iskitimcement» and «SLK-Cement» were used. The introduction of 10% metacaolin HMK-45 and metha-caolin waste after the production of foam glass allows to obtain fine-grained con-cretes with increased compressive strength both in the early stages of hardening and at the design age on cements containing different amounts of C3S. The high amount of C3S in cement during hydration leads to an increased release of por-tlandite, which is bound by the aluminosilicate additive metakaolin due to its volcanic activity with the formation of calcium hydrosilicates and additional cementation products, followed by strengthening of the composite stone structure. The existing «Iskitimcement» (67.0%) has a higher amount of C3S compared to «SLK-cement» (62.0%), as a result, a greater amount of portlandite released during its hydrolysis. The authors noted a greater hardening of fine-grained concrete when 10% metacaolin was introduced into a cement-based composition with a high content of C3S in the early and late periods of hardening.