Title: Breakage mechanics for granular materials in surface-reactive environments

Abstract

It is known that the crushing behaviour of granular materials is sensitive to the state of the fluids occupying the pore space. Here, in this work, a thermomechanical theory is developed to link such macroscopic observations with the physico-chemical processes operating at the microcracks of individual grains. The theory relies on the hypothesis that subcritical fracture propagation at intra-particle scale is the controlling mechanism for the rate-dependent, water-sensitive compression of granular specimens. First, the fracture of uniaxially compressed particles in surface-reactive environments is studied in light of irreversible thermodynamics. Such analysis recovers the Gibbs adsorption isotherm as a central component linking the reduction of the fracture toughness of a solid to the increase of vapour concentration. The same methodology is then extended to assemblies immersed in wet air, for which solid-fluid interfaces have been treated as a separate phase. It is shown that this choice brings the solid surface energy into the dissipation equations of the granular matrix, thus providing a pathway to (i) integrate the Gibbs isotherm with the continuum description of particle assemblies and (ii) reproduce the reduction of their yield strength in presence of high relative humidity. The rate-effects involved in the propagation of cracks and themore » evolution of breakage have been recovered by considering non-homogenous dissipation potentials associated with the creation of surface area at both scales. It is shown that the proposed model captures satisfactorily the compression response of different types of granular materials subjected to varying relative humidity. This result was achieved simply by using parameters based on the actual adsorption characteristics of the constituting minerals. The theory therefore provides a physically sound and thermodynamically consistent framework to study the behaviour of granular solids in surface-reactive environments.« less

Authors:

Zhang, Yida ^[1]; Buscarnera, Giuseppe ^[2]

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+ Show Author Affiliations

1. Univ. of Colorado, Boulder, CO (United States)
2. Northwestern Univ., Evanston, IL (United States)

Publication Date:

Sat Nov 11 00:00:00 EST 2017

Research Org.:

Northwestern Univ., Evanston, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1538478

Alternate Identifier(s):

OSTI ID: 1549083

Grant/Contract Number:  

SC0017615

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the Mechanics and Physics of Solids

Additional Journal Information:

Journal Volume: 112; Journal Issue: C; Journal ID: ISSN 0022-5096

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Materials science; Mechanics; Physics