Compression characteristics of an artificially mixed soil from confined uniaxial compression tests

The present study focuses on the compression characteristics of a crushed sandstone-mudstone particle mixture. The mixture is artificially prepared by mixing sandstone particles and mudstone particles (MP) on the basis of five scheduled particle size distribution (PSD) curves and six MP contents by weight. In order to investigate the compression characteristics, 120 confined uniaxial compression tests are performed. The compression curve for each specimen, which represents the relationship between the logarithm (base 10) of the applied stress and void ratio, is obtained from test data. Two defining features of the compression curve, namely the compression index (I-c) and pre-compression stress (sigma(p)), are determined. The effects of two-type factors on the two parameters I-c and sigma(p) are analyzed. Factors of the first type are the properties of tested material, which include the PSD curve [the characteristics of which are denoted by the median particle diameter (D-50), gravel content (G(c)), non-uniformity coefficient (C-u), curvature coefficient (C-c), characteristic size (alpha), PSD shape (beta)], and MP content by weight (MPc). Factors of the other type are the properties of the specimen, which include the initial water content (w), initial dry bulk density (rho(d)), and initial void ratio (e(0)). The results indicate that both the parameters I-c and sigma(p) are correlative with the properties of the tested material and specimen.