When a colloidal suspension is dried, capillary pressure may overwhelm repulsive
electrostatic forces, assembling aggregates that are out of thermal equilibrium. This poorly
understood process confers cohesive strength to many geological and industrial materials.
Here we observe evaporation-driven aggregation of natural and synthesized particulates,
probe their stability under rewetting, and measure bonding strength using an atomic force
microscope. Cohesion arises at a common length scale (∼ 5 μm), where interparticle …

Earh's surface is covered with soil; particulate mixtures subject to cycles of wetting and
drying. The role of this transient hydrodynamic forcing in creating and destroying aggregates
is virtually unexplored. We examine this process at the grain scale. When a colloidal
suspension is dried, capillary pressure may overwhelm repulsive electrostatic forces,
assembling aggregates that are out of thermal equilibrium. This poorly understood process
confers cohesive strength to many geological and industrial materials. Here we observe …