Simulating the drying behavior of rammed earth columns

Rammed earth construction provides an efficient alternative construction material to limit energy consumption and CO2 emission. It possesses various characteristics of a sustainable material, but its mechanical capacity is sensitive to humidity variations. It is, therefore, important to better understand water transport within rammed earth when subjected to varying ambient conditions. In this context, the present work aims to analyze the hydraulic behavior of a reduced piece of rammed earth wall consisting of a column of size 14cm x 14cm x 30cm subjected to drying from the initial compaction water content in an indoor environment. The columns had transient non-uniform relative humidity, which was measured in-situ. Thermo-hydraulic coupled numerical modeling was developed using realistic atmospheric boundary conditions. The material and hydric parameters were chosen from an experimental study previously performed at the material scale. A parametric study was performed in order to evaluate the sensitivity of the modeling to both material parameters and boundary conditions. The results of the numerical simulations were highly sensitive to parameter values used for the water retention curve and the surface mass transfer coefficient, with a satisfactory matching of experimental results only achieved after adjusting initial estimates of relevant parameter values