Mechanical and electrical properties of concrete modified by carbon nanoparticles
The article presents the study of obtaining electrically conductive concrete using carbon nanoparticles obtained by processing coal in an electric-discharge plasma reactor. An electric-discharge method for producing a sedimentation-resistant and highly dispersed suspension consists in treating coal powder with an electric current in an aqueous medium. Using laser diffraction, it was found that carbon nanoparticles have a particle size in the range from 50 to 500 nm. The microstructure of hardened cement paste was studied using SEM. The compressive strength was tested on cubes with an edge of 100 mm according to EN 12390-6. Determination of the electrical resistance of concrete was carried out on specimens with an edge of 100 mm, placed between two brass plates, through which direct current was passed. The optimum content of carbon nanoparticles (0.01–0.1 % wt.) in the binder is evaluated, which allows to obtain high mechanical properties (30–35 % higher compressive strength compared to a control specimen. It is proved that the mechanism of action of nanoscale modifiers is most manifested in small doses. The dependences of the physicomechanical properties of Portland cement upon the addition of various amounts of carbon nanoparticles are determined. Physicomechanical and exploitation properties of heavyweight electrically conductive concrete are determined. The kinetics of changes in the electrical resistance of concrete at different curing periods is established.