International audienceLarge-scale evaporation experiments were conducted on bare sand using an environmental chamber. Four different atmospheric conditions and various drying durations were imposed to soil sample. Both the atmospheric parameters (air flow rate, relative humidity and temperature) and the response of soil (volumetric water content, temperature and soil suction) were monitored simultaneously. Notably, the temperature and matric suction at soil surface were monitored using infrared thermometer and high-capacity tensiometer, respectively. The results show that the air and soil temperatures depend on the evaporation process and atmospheric conditions. In addition, volumetric water content in the near-surface zone is strongly affected by the evaporation process and changes linearly over depth. The evaporation rate is strongly dependent on the air conditions

International audienceThis study aims at evidencing the effects of lime treatment on the microstructure and hydraulic conductivity of a compacted expansive clay, with emphasis put on the effect of lime hydration and modification. For this purpose, evolutions of hydraulic conductivity were investigated for both lime-treated and untreated soil specimens over 7 d after full saturation of the specimens and their microstructures were observed at the end. Note that for the treated specimen, dry clay powder was mixed with quicklime prior to compaction in order to study the effect of lime hydration. It is observed that lime hydration and modification did not affect the intra-aggregate pores but increased the inter-aggregates pores size. This increase gave rise to an increase of hydraulic conductivity. More precisely, the hydraulic conductivity of lime-treated specimen increased progressively during the first 3 d of modification phase and stabilised during the next 4 d which correspond to a short period prior to the stabilisation phase. The microstructure observation showed that stabilisation reactions took place after 7 d. Under the effect of stabilisation, a decreasing hydraulic conductivity can be expected in longer time due to the formation of cementitious compounds

Analyse des rôles de la microstructure et de la composition minéralogique de trois sols argileux du bassin de Paris sur leur sensibilité au retrait-gonflement Résumé En France, depuis 1976, des périodes de sécheresse prolongée, associées à des déficits hydriques importants, ont mis en évidence une grande vulnérabilité des maisons individuelles fondées sur des sols argileux. Cet article présente les caractéristiques minéralogiques, microstructurales et géotechniques de trois formations argileuses du bassin de Paris, sensibles aux processus de retrait-gonflement. Les Argiles Plastiques (AP) du Sparnacien, non carbonatées, sont comparées aux Argiles Vertes de Romainville (AVR) du Rupélien et aux Marnes Bleues d'Argenteuil (MBA) du Ludien. Les contributions de la composition minéralogique et de la microstructure sur leur sensibilité au retrait-gonflement sont étudiées, en particulier en comparant des matériaux intacts et des matériaux remaniés au laboratoire.