Micromechanically inspired investigation of cemented granular materials: part I-from X-ray micro tomography to measurable model variables

Cemented granular materials are abundant in nature and are often artificially produced. Their macroscopic behaviour is driven by small-scale material processes, which are generally classified as: grain breakage, cement damage and fragment rearrangement. This paper presents an experimental analysis of the latter two processes as observed through in-situ X-ray tomography and quantified by a suite of novel image processing approaches. This allows for example all particles and the bonds between them to be identified and their evolution to be individually quantified on a statistically representative volume, in 3D, throughout a loading test. We reveal the high spatial correlation between cement damage and strain rate and their effect on the isotropy of the bonds. Being the second of a two-part contribution, the overarching aim of this paper is to propose a general framework for the micro-inspired study of cemented granular materials. This is developed here, in Part I, in terms of multi-scale experimental quantification at sample and grain-level, while in Part II in terms of a two-way interaction with micro-inspired constitutive modelling.