Flow velocity-dependent transition of anisotropic crack patterns in CaCO$_3$ pastes

TL;DR

This study explores how the velocity of forced vibration influences the orientation of crack patterns in CaCO$_3$ pastes, revealing a transition from perpendicular to parallel crack alignment at a specific threshold velocity.

Contribution

It uncovers the velocity-dependent transition in crack pattern orientation and links it to particle reorientation caused by oscillatory flow.

Findings

Crack pattern orientation changes at a threshold vibration velocity.

Particle reorientation under oscillatory flow causes the transition.

Anisotropic crack patterns depend on vibration velocity.

Abstract

We investigate the desiccation crack patterns on the surface of a drying paste made of calcium carbonate (CaCO$_3$) powder and distilled water. Forced vibration of the CaCO$_3$ paste prior to drying results in an anisotropic crack pattern, in which many long cracks develop along a specific preferred direction. We reveal that the preferred direction changes from perpendicular to parallel to the vibration direction at the threshold velocity of vibration. The transition is attributed to the reorientation of constituent particles subjected to the forced oscillatory flow of fluid in the paste.