Assessment of the influence of additives in concrete by the Raman spectroscopy method

Abstract

The effect of nano SiC additives with a particle size less than 50 nm, carbon black with a specific surface of about 80 m2/g, SiO2 and Al2O3 zol, AlCl3, FeCl3 solutions on the composition of silicon-oxygen anions in the pure C-S-H phase and hydrated cement was studied. The mixture was pressed at a specific pressure of 100 MPa and tested for compressive strength after 1, 7 and 28 days of normal aging. The Raman spectroscopy method was used to determine the composition of silicon-oxygen anions (SOA) in the C-S-H phase of cement and compared it with the strength of the stone, as well as with the SOA composition in the pure C-S-H phase. It was found that the initial powder of the C-S-H phase mainly contains isolated Q0 and terminal Q1 tetrahedra [SiO4]. Pressing the powder at 100 MPa leads to the advanced formation of chains of crosslinking Q2 and Q3 tetrahedra. The addition of silica to C-S-H promotes maximum chain formation from Q2. The Raman spectrum of C-S-H with silica zol is identical to the spectrum of hydrated cement. Iron chloride prevents the formation of extended chains of silicon-oxygen tetrahedrons. Carbon-containing nano-additives significantly alter the spectrum of C-SH calcium substructures.