Features of the influence of carbonaceous nanoparticles on the rheological properties of cement paste and technological properties of the fine-grained concrete

The article describes the technological features of the manufacture of cement concrete road with carbonaceous nanoparticles. The research was carried out to determine the influence of the carbonaceous nanoparticles (CNP) on the properties of cement paste and monominerals cement clinker. The method of determination of mobility and the viscosity of the cement paste due to vibration has been developed. It is shown that the optimal content of the CNP in the cement paste leads to increase of its mobility and reduced viscosity. Introduction of CNP into the cement paste helps to prolong the life setting. The investigations of zeta potential of the suspensions of the cement and cement clinker monominerals with CNP have been done. They showed that the introduction of the CNP into suspension monominerals cement clinker tricalcium aluminate (S3A) and tetracalcium alyumoferrita (S4AF) leads to dramatic increase of electronegativity and the change of the sign of the potential of these monominerals to the opposite. The effect of carbonaceous nanoparticles on the mechanical and structural characteristics of the cement stone and concrete with CNP was determined. It is shown that the effectiveness of the impact of the CNP on the processes of structure decreases when shifting from submikrostructure to micro-structure and further to meso- and macrostructure. Efficacy of CNP depends on the concrete mixtures compaction method: hard mixture compression or vibropressing leads to two times larger increase in strength when introducing CNP than vibration compaction of moving mixtures. The electron-microscopic studies of the structure of vibrocompacted and pressed cement stone and concrete have been done. One can observe that in the structure of concrete with CNP there are spatial frames inside and around which tumor crystallization takes place. That intensifies the processes of structure formation. Concrete with CNP can be characterized by prevailing dense structure, the scour boundary at the contact zone between the cement matrix and filler, uniform and dense structure, the porosity of the mortar is negligible and presented by micropores. Application of CNP improves the performance properties of concrete: increased frost resistance, reduced water absorption and abrasive.