Gel-like mechanisms of durability and deformability in wet granular systems

It is known empirically that dry granular materials tend to crumble and that wetting them greatly increases their strength. Although the mechanism of the macroscopic material strength is known in homogeneously wetted granular system, the material strength in heterogeneously wetted granular system is not known due to the lack of experimental studies. Here, we focus on sand grains coated with silicone oil, whose wettability is stable with respect to time, and constructed a model system that can control the heterogeneity of interaction by mixing coated sand grains. The results show that the rapid increase in Young’s modulus is due to a rigidity percolation transition, and that the recombination of the network makes the material more resistant to deformation. This system leads to understanding the properties of jamming systems such as glasses, emulsions, and foams, where the effects of attractive interactions and rigidity percolation have been still unclear.