INVESTIGATION OF THE STRUCTURE OF A CEMENT COMPOSITE MODIFIED BY HYDROTHERMAL SiO2 NANOPARTICLES AND MCNT NANOPARTICLES BY THE X-RAY PHASE ANALYSIS METHOD

The x-ray phase analysis method has been used to study the eff ects of small doses of hydrothermal SiO₂ nanoparticles and nanoparticles of multiwalled carbon nanotubes (MCNTs) on the structure of a Portland cement composite separately and in a combination at the age from 4 h to 28 days. It has been established that clinker minerals and Portlandite components do not diff er signifi cantly in nanomodifi ed specimens compared to control specimens, which agrees with the thermogravimetrical data for the ages of 1 and 28 days. In the region of the angles 2θ = 5–12 degrees, structural diff erences were identifi ed for the CSH gel in the nanomodifi ed specimens: at the age of 1 day (24 h), there were CSH peaks (I) in the diff raction patterns of the modifi ed specimens with Basel distances of 12.44–12.54 Å between the layers. At the age of 28 days, relatively higher peaks of a tobermorite-like structure were identifi ed with a Basel distance reaching a maximum value of 14.54 Å in a specimen modifi ed by a combination of SiO₂ and MCNT nanoparticles. The increase in the Basel distances corresponds to a reduction in the values of the Ca/Si ratio and an improvement in the ordering of the CSH-gel structure and agrees with the IR-spectroscopy data having shown the higher degree of polymerization of silicon–oxygen tetrahedrons in nanomodifi ed specimens.
   
Author:  E. N. Polonina, V. V. Potapov, S. A. Zhdanok, S. N. Leonovich
Keywords:  cement composite, SiO2 nanoparticles, MCNTs, x-ray phase analysis, CSH-gel structure, Basel distances, Ca/Si ratio
Page:  215