Shear strength-dilation characteristics of cemented sand-gravel mixtures

Although a number of researches have been carried out on cemented sands or cemented well graded gravely sands, the mechanical behavior of cemented poorly graded sand-gravel mixtures has not been studied well. In the present paper, shear strength-dilation characteristics of a poorly graded cemented sand-gravel mixture has been investigated using large scale direct shear tests. The studied soil consisted of uniform sand mixed with 30% uni-sized gravel particles. Portland cement was used as the cementing agent and was added to the base soil in different contents. Cemented mixture was cured for 7 days and then was tested using a 30063006170 mm direct shear apparatus. Cement content, relative density, and surcharge pressures were considered as the variables of testing program. Maximum and constant volume friction angles besides the maximum angle of dilation were determined using the experimental data. Based on the results, increase in cement content and relative density increased maximum friction angle and angle of dilation. However, dilation angle decreased with increase in surcharge pressure. Using the experimental results, a framework was developed for shear strength-dilation relation in cemented poorly graded sand-gravel mixtures. Moreover, some empirical relationships were suggested to obtain shear strength parameters of cemented mixture based on associated values in uncemented samples.