Tensile strength identification of remolded clayey soils

The tensile strength of soil is a major mechanical parameter controlling the development of tensile cracking, which is commonly encountered in many earth structures. This paper aims to identify the tensile behavior of different clayey soils. On one hand, the properties of unsaturated clayey soils were analyzed. On the other hand, the influence of the mineralogy of clays on tensile strength was investigated. Four types of soils with very different properties were investigated: the kaolin P300, which is a low plasticity clay, the montmorillonite clay with high plastic limit and swelling behavior, and two mixtures of these two clays with intermediate behaviors. For the tensile tests, the approach consisted in using a specific tensile device which allowed imposing the tensile load and measuring the global displacement under nil confining stress. The originality of the article is to combine Digital Image Correlation (DIC) technique with tensile test on clayey soil slurries with different mineralogies. Four parameters were chosen to identify the tensile behavior of the slurries in this research: the maximum tensile stress, the mean stress modulus (E₅₀), the secant modulus at the axial strain of 10⁻³, and the strain anisotropy ratio. The results highlighted the influence of water content, suction, and mineralogy on the tensile behavior of the materials.