Efficiency of modifying cement hardening systems with nanoadditive based on SiO2 and superplasticizer

Abstract

The synthesis and research of a complex nanoscale additive based on silica and superplasticizer of the Sika ViscoCrete T100 brand was carried out. The optimal dosage of superplasticizer (0.2% by weight of cement) was established, which allows to obtain silica particles with a size of 4–12 nm, stable for 7 days from the start of synthesis. The influence of the obtained complex nanoscale additive on the processes of setting, hydration, structure formation and strength gain of the cement hardening system is studied. It is determined that the maximum value of plastic strength (580 kPa) in the nanomodified cement hardening system is achieved with a minimum setting start time (210 minutes). At the same time, the hydration process is intensified – after 28 days of hardening, the value of the degree of hydration in this system is 93%, which is 1.4 times more than in the reference cement – water system. The high strength characteristics of the nanomodified cement stone (62 and 93 MPa on the 1^st and 28^th day of hardening, respectively) are due to the formation of mainly low-base calcium hydrosilicates in its structure.