Effect of mechanical impact on the microstructure and IR spectra of cohesive soil

The aim of the study is to determine the correlations between mechanical impacts on clay soil samples and resulting changes in the microstructure of the samples and their IR spectra. For research, soil from a railway subgrade under construction in the Azov-Black Sea region was used. The soil was examined by traditional and modern physical methods and classified as light clay. Clay properties were modified by adding alabaster to the soil, after which the samples with different amounts of alabaster were subjected to mechanical load. A cyclic mechanical impact by the compression method was applied to a clay sample without alabaster, an equivalent to the passage of 400 freight trains along the railway track. The microstructure of samples was studied by electron microscopy which allowed determining the microstructure parameters of the fragments of samples before and after the mechanical action. Samples of clay and clay with the addition of alabaster were subjected to a semi-quantitative express analysis by IR spectroscopy, as a result of which the concentrations of minerals were determined with an accuracy of no worse than 10%. Clay and clay samples with the addition of alabaster were subjected to static uniaxial compression, after which the samples were examined by IR spectroscopy. Comparison of the results of spectral and compression studies made it possible to investigate the correlations between changes in the peak intensities of the IR spectra bands and the concentration of alabaster, as well as the strength properties of the soil.