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AbstractExperimental studies have been undertaken to understand the link between hydric state and mechanical behaviour of rammed earth. Prismatic rammed earth sample of 15 cm × 15 cm × 45 cm, structured as a wall element with several layers, were subjected to one dimensional drying in laboratory. The kinetic of drying was monitored by continuous weighing the sample and humidity measurement at a regular interval. Suction was then used to represent the hydric state. Simultaneously, unconfined compressive strength was performed after 0, 2, 3, 4, 6, 8 and 19 weeks of drying. Digital image correlation was used to determine the stiffness of samples. Results show an increase up to 60% of the maximum in compressive strength in the first 3 weeks of drying which is correlated with a sharp decrease in water content in the sample. The suction was correlated with the evolution of mechanical performances of the samples during the drying.

Rammed earth structures are very sensitive to hydric conditions. Experimental studies have been undertaken to understand the link between liquid water transfer and mechanical behavior at structural scale. This study was done on a prismatic rammed earth sample of 15cm x 15cm x 45cm, structured as a wall element with several layers. Samples were subjected to one dimensional drying in an indoor environment. Humidity and temperature sensors were placed on each layer inside the sample. The kinetic of drying was monitored by continuous weighing the sample and humidity measurement at a regular interval. Results of water content evolution suggest that samples dry in two stages; the first stage is associated with relatively high evaporation flux of 13.88 g m-2h-1 while the second stage has very low flux of moisture evaporation. Unconfined compressive strength was performed in drying samples after 0, 2, 6 and 8 weeks of drying. In parallel, digital image correlation was used to determine the stiffness of samples. Results show an increase in compressive strength by the rate of 98 kPa per week in the first two weeks, then this rate reduces to 23 KPa per weeks after 8 weeks. These experimental results will allow to enhance the 3D hydro mechanical numerical model developed in the laboratory.