Drying, cracks and shrinkage evolution of a natural silt intended for a new earth building material. Impact of reinforcement

• Study treats natural silt constituting new raw earth concrete patented.
• Relation between suction and water content were established.
• Tensile resistance was deduced from the corresponding suction value.
• Strain evolution was discussed: local heterogeneity causes crack appearance.
• Adding reinforcement to natural silt reduces crack ratio by a factor around 10.

Series of drying tests are carried out on natural silt intended for the preparation of new raw earth concrete. This technique is different from rammed earth. The study treats the drying of various formulations of the natural silt with and without reinforcement. No binders were added to highlight the impact of reinforcement. Global and local deformation around a single crack are analysed using image processing. Adding reinforcements to natural silt reduces the percentage of cracking by a factor around 10. The suction is derived from water content corresponding to crack appearance and correlated to the ultimate resistance of the material.