Shear Strength Characteristics of an Artificially Cemented Sand-Gravel Mixture

Over the years, a number of researches have been carried out to describe the behavior of granular soils. However, the mechanical behavior of cemented granular soils is not well understood. Indeed, shear strength and dilation characteristics are different from uncemented soils. The lack of experimental data for illustration of the mechanical behavior of cemented soils is more obvious for cemented sand-gravel mixtures.In this paper, shear strength-dilation behavior of artificially cemented sand-gravel mixtures has been studied using large direct shear tests. The soil consists of fine sand mixed with 30% uni-sized gravel particles with maximum size of 12.5 mm. Large direct shear tests have been conducted using saturated samples in a 300×300×170 mm shear box. Samples were prepared in four different relative densities of 30, 50, 70 and 90% and three cement contents of 0, 1 and 2% and were tested under two surcharge pressures of 77 and 150 kPa. Cemented samples were cured in direct shear box for seven days under a low water head to prevent degradation of cemented bonds. After curing, shear loading was applied at a constant rate of 0.1 mm/min. Both horizontal and vertical displacements besides shear stresses were recorded during loading process. Shear strength, friction angle and cohesion intercept of cemented samples were calculated and it was indicated that shear strength of cemented sand-gravel mixtures increase with cement content and relative density. However, dilation of cemented samples reduced with increase in surcharge pressure.