Freestanding loadbearing structures with Z-shaped particles

TL;DR

This paper demonstrates that Z-shaped particles can form freestanding, load-bearing granular columns with high aspect ratios, combining experiments and simulations to explore their stability and unique mechanical properties.

Contribution

It introduces a novel method for creating slender, freestanding structures using non-convex Z-shaped particles that entangle and stabilize under load, advancing granular material design.

Findings

Z-shaped particles enable stable, freestanding columns with high aspect ratios.

Granular aggregates exhibit strong strain-stiffening and anisotropic stress propagation.

Structures withstand compression, bending, and vibration tests effectively.

Abstract

Architectural structures such as masonry walls or columns exhibit a slender verticality, in contrast to the squat, sloped forms obtained with typical unconfined granular materials. Here we demonstrate the ability to create freestanding, weight-bearing, similarly slender and vertical structures by the simple pouring of suitably shaped dry particles into a mold that is subsequently removed. Combining experiments and simulations we explore a family of particle types that can entangle through their non-convex, hooked shape. We show that Z-shaped particles produce granular aggregates which can either be fluid and pourable, or solid and rigid enough to maintain vertical interfaces and build freestanding columns of large aspect ratio (>10) that support compressive loads without external confinement. We investigate the stability of such columns with uniaxial compression, bending, and vibration tests and compare with other particle types including U-shaped particles and rods. We find a pronounced anisotropy in the internal stress propagation together with strong strain-stiffening, which stabilizes rather than destabilizes the structures under load.