Drying experiment on rammed earth structure

Experimental studies have been undertaken to understand the link between hydric state and mechanical behaviour of rammed earth. Prismatic rammed earth sample of 15 cm x 15 cm x 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.