The effect of cement material properties on the fracture patterns developing within cement-covered brittle sphere under
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RESEARCH PAPER
The effect of cement material properties on the fracture patterns developing within cement-covered brittle sphere under impact Sheng Jiang1 • Luming Shen1
•
François Guillard1 • Itai Einav1
Received: 13 October 2018 / Accepted: 20 March 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Dynamic loading experiments of single glass bead cement-covered by epoxy resins of different compositions demonstrate the existence of diverse fracture patterns under similar impact velocities and high strain rates. A comparison of these fracture patterns between different resin compositions highlights two distinctive fracture mechanisms, namely cementfocused fracture and grain-focused fracture mechanisms, which is affected by the interface adhesion toughness. The transition between those patterns is characterised by the damage of the cement/grain interface adhesion. Using Fourier transform of the X-ray micro-computed tomography images, the details of the locality of the damage within the cemented bead are then quantitatively analysed, as well as the preferential crack orientation. Several sporadic curved cracks are observed near the cement/grain interface region in the cement-focused fracture cases, roughly along the interface. However, for grain-focused fracture cases, damage is most likely to occur along the central loading axis area of the cemented bead and prevailingly forms diametric cracks along the impact direction. The results of this study are expected to help advancing the development of models that predict the deterioration of brittle cemented geomaterials under impact. Keywords Dynamic fracture Cemented granular material Crack orientation Hopkinson bar X-ray micro-computed tomography Fourier transform
1 Introduction Cemented granular materials (CGMs) can be found in various forms, either in naturally occurring or in artificially manufactured forms, and are of wide interest across geosciences and engineering. Well-known natural examples include calcite, quartz and clay cemented sands, as well as sedimentary rocks such as sandstones, conglomerates and breccias [1]. Artificial materials include asphalts, mortars, concretes, solid propellants and high explosives [2–4]. Understanding the dynamic mechanical behaviour of these CGMs can help develop new solutions to practical engineering problems including rock blasting, fracking-induced artificial earthquake, landslides and deterioration of metaconcrete structures [5]. These materials have a similar underlying texture consisting of densely packed grains with & Luming Shen [email protected] 1
School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
a solid matrix filling partially or totally the interstitial space and sticking to the grains. For this reason, besides the grain properties and intergrain configurations, the mechanical behaviour of these cemented granular materials is drastically affected by the additional cementation effect [6]. Th
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