This study, which presents the results of numerous tests on the sensitivity of mortar permeability under conventional triaxial loading, represents tests carried out over more than a year at various confining pressures under monotonic loading or with loading-unloading cycles. Permeability is measured on a sample, dried prior to the test, by injecting argon -a neutral gas. A description of the experimental method based on applying a permanent flow is given as well as the technique of test study used. In this work, we chose to measure permeability under loading at different levels ofdeviatoric stress and strain since this corresponds more closely to the real conditions under which the works are used. Preliminary tests showed that the permeability under load was susceptible to early appearance of microcracks and began to increase noticeably towards 75/80% of the stress peak. Further tests were then carried out with loading-unloading cycles for stress levels beyond the stress peak. The authors have shown that permeability increases very rapidly, starting from this peak. This is irreversible as the measurements taken after unloading the sample prove. The different tests also prove that the damage level is insufficient to allow for a description of variation in permeability, as it clearly depends on the degree to which the microcracks have opened. Such a claim is supported by results where this variation is presented in relation to lateral strain.
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