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This paper presents a laboratory study of the influence of relative density on the liquefaction potential of a sandy soil using the triaxial apparatus. The study is based on undrained triaxial tests performed on samples at an initial relative density RD = 15, 50 and 65 % under a confining pressure of 100 kPa using a dry deposition method. Samples were subjected to quasi-static undrained cyclic tests. The paper is composed of three parts. In the first part the used materials and their characteristics are presented. The second part is devoted to the experimental procedures and the device used. The third part investigates the influence of relative density on the liquefaction potential of the three sands (Hostun Rf, Chlef and Rass). This study also explores the influence of particle size on the liquefaction potential. The test results indicate that consistent results were obtained and show clearly that increasing the relative density leads to an important improvement in the liquefaction resistance of sand. This effect is very pronounced when the initial relative density increases from 50 to 65 %.

The complex impedance spectroscopy (CIS) method is usually used in order to analyze the electrical response of different semiconducting disordered materials as a function of frequency at different temperatures. The real and imaginary parts of the complex impedance can show different semicircles in the complex plane that give evidence for the presence of both bulk and grain boundary contributions. Many parameters can be deduced from the analysis of CIS data, such as relaxation times and activation energies. There are some literature data concerning electrical properties of clays and (semiconductor, sand, cement,…)/clay mixtures. Most of the published works are related to the AC conductivity of rocks with the effect of water or oil content but there are no similar studies on the characterization of the microstructure of individual clays as ceramic materials by analyzing their temperature and frequency dependence of their electrical conductivities. Hence, this paper presents an analysis of electric complex impedance of the Fe2O3/Kaolin composite in the high temperature range up to 740 °C. Sinusoidal voltage with frequency in the range [100 Hz, 1 MHz] is applied to the material in order to measure the electrical conductivity for various concentrations of Fe2O3 from zero to 100 %. The activation energies for the conduction and for the relaxation processes are determined and their dependence on the density of Fe2O3 analyzed. Furthermore, let’s found that Fe2O3 have the effect to increase the electrical conductivity in our samples. From the Nyquist diagrams, only one semi-circle related to the contribution of the grains to the total electrical conduction is identified for all investigated samples.

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