Relevance and Efficiency of Using Nanosized Particles in Structuring Cement Pastes

Abstract

The relevance of the use of nanosized particles in the structuring of cement pastes is due to the ability at the micro level to control the processes occurring during the hardening of cement. And it also provides the ability to purposefully control the composition of hydrated neoplasms. Plasticizer-stabilized aqueous suspensions of nanosized particles of non-hydraulically active materials in a cement matrix cause forced crystallization of hydrated neoplasms from a supersaturated liquid phase. And they act as seeds introduced from the outside, on the surface of which neoplasms are concentrated, that subsequently combine into conglomerates that make up the structure of a cement stone. The formation of the structure of the cement matrix occurs without the formation of large the portlandite fields, which are typical for no additive portland cement. The structure of a cement stone with nanosized particles is represented by poorly crystallized flaky calcium hydrosilicates. It was found that the degree of hydration of cements with suspensions of nanoparticles is 15-18% higher. The efficiency of using nanosized particles in structuring cement pastes is giving the cement paste mobility in the initial period of hydration and the possibility of plasticizing it without blocking the surface of cement particles with surfactants. On the other hand, it makes it possible to obtain dense and durable structures of a cement matrix with improved physical and mechanical characteristics. The porosity of cements with suspensions is lower on 15 - 20%, and after 28 days of hardening it is lower on 20 - 35% than that of non-additive cement. And the strength of the samples after 24 hours increased 1.5 - 1.8 times (from 19.5 to 27 - 34 MPa), at the brand age by 15 - 24% (from 64 to 75 - 80 MPa)