Modification of the structure and Properties of Fine-Grained Concrete with Carbon Black Dispersion

Abstract

The study shows that adding carbon black (soot) in the form of an aqueous dispersion into the composition of fine-grained concrete leads to an increase in bending and compressive strength of the samples: At a soot concentration of 0.005% by weight of cement, respectively, to 37.63 and 15.99%, at a concentration of 0.02% up to 26.39 and 26.39% due to compaction of the structure of the cement matrix. An intensification of cement hydration processes has been noted, confirmed by the results of IR-spectral, differential-thermal analyses and studies of the cement matrix microstructure in the composition of fine-grained concrete. On the surface of new formations in the composition of modified soot dispersion, the formation of needle-like crystals has been observed. On their surfaces, structures of spherulites formed with sizes ranging from 100 to 200 nm, which are typical for calcium hydro-sulfonic aluminates of 3CaO•Al2O3•3CaSO4•32H2O type. The formation of spherulites is observed in the pores of the cement matrix, which contributes to additional compaction of the structure of fine-grained concrete.