David Grégoire's research group @ UPPA

Bioinspiration: failure and damage identification in natural seashells and translation to synthetic composites or biohybrid materials

Abstract

Many materials found in nature are comprised of relatively weak materials, yet they still exhibit superior mechanical performance. This performance originates within elegant hierarchical structures. Nacre exhibits remarkable strength and toughness despite its composition of greater than 95% aragonite, a brittle ceramic. By incorporating just 5% soft biopolymer into a hierarchical structure with the brittle ceramic, nacre is ~1000 times tougher than pure aragonite. This significant increase in toughness stems from toughening mechanisms that act at multiple length scales within the hierarchical structure. A better knowledge of these mechanisms is at sake in material science because they can be directly translated to synthetic materials - biomimicry approach - or we can also directly incorporate these natural materials into synthetic materials to create hybrid biomaterials.

Characterization of failure mechanisms in natural nacre

Recyling sea shells in environmental-friendly concrete

100% replacement of the granular skeleton
by Crassostrea gigas oyster shell

Recyling sea shells for geothermal well cementation

People

Opening positions

Current people in the group:

Andrew Wilson
MSc/PhD student
Recycling of natural and industrial wastes for environmental-friendly and high-performance multifunctional cement-based grouts

(MSc defense 13-09-2021)(PhD defense in 2024)

Tematuanui a Tehei Hantz
MSc/PhD student
Use of French Polynesia Pinctada pearl oyster shells for environmental-friendly concrete

(MSc defense 13-09-2021)(PhD defense in 2024)

Alumni

Elvis Baffoe
MSc student

On the evaluation of Oyster and Nacre as high performance cement-based grouts for geothermal well cementation(MSc defense 15-07-2019)
Now: PhD studentUniv. Miami, USA

Audrey Gabard
MSc student (M1)

Recycling sea shell wastes in drilling fluids(M1 defense 26-06-2019)

Ana Cláudia Pinto Dabés Guimarães

PhD StudentUse of oyster shell (Crassostrea gigas) as aggregate replacement for producing environmentally-friendly concrete(PhD defense 09-05-2022)

PhD Manuscript

Following position:
Sustainability and carbon reduction advisor
BAM Nuttall
UK

Other collaborators:

France

University Pau & Pays Adour

Dr. Céline Perlot-Bascoulès

USA

Northwestern University

Pr. Horacio D. Espinosa

Connected publications

Granular Skeleton Optimisation and the Influence of the Cement Paste Content in Bio-Based Oyster Shell Mortar with 100% Aggregate ReplacementThe purpose of this paper is to propose a methodology to optimise the granular skeleton assembly of cementitious materials containing non-spherical aggregates. The method is general and can be applied to any granular skeleton whatever the aggregate shape, size, or composition because it is simply based on the direct minimisation of the inter- granular porosity to consequently increase the skeleton’s compactness. Based on an experimental design approach, this method was applied to and validated for bio-based oyster shell (OS) mortar with 100% aggregate replacement. First, the best combination of seven crushed oyster shell particle classes was determined and compared with a stan- dardised sand skeleton (0/4 mm) and three other non-optimised OS gradings in terms of intergranular porosity. In particular, it is shown that simply mimicking a reference grading curve initially designed for spherical particles with non-spherical particles led to poor performances. Then, different mortars were cast with the standardised sand skele- ton, the optimised OS grading, and the three other non-optimised OS gradings by keeping the water-to-cement ratio (0.5), the aggregate bulk volume, and the cement paste content constant. Mechanical tests in compression confirmed the higher performance of the optimised OS mortar, validating the global optimisation approach. However, the high elongation of the oyster shell aggregates led to high skeleton intergranular porosities -- even after optimisation -- and the cement paste content needed to be adapted. For a given granular skeleton and for a constant aggregate bulk vol- ume, the increase of the cement paste content led to an increase of both the filling ratio and the mechanical properties (compressive and flexural strengths). Finally, it is shown that the proposed skeleton optimisation and a cement paste content adjustment allowed recovering good mechanical properties for an oyster shell mortar with 100% aggregate replacement, especially in flexural tension.

Tablet-level origin of toughening in abalone shells and translation to synthetic composite materialsNacre, the iridescent material in seashells, is one of many natural materials employing hierarchical structures to achieve high strength and toughness from relatively weak constituents. Incorporating these structures into composites is appealing as conventional engineering materials often sacrifice strength to improve toughness. Researchers hypothesize that nacre's toughness originates within its brick-and-mortar-like microstructure. Under loading, bricks slide relative to each other, propagating inelastic deformation over millimeter length scales. This leads to orders-of-magnitude increase in toughness. Here, we use in situ atomic force microscopy fracture experiments and digital image correlation to quantitatively prove that brick morphology (waviness) leads to transverse dilation and subsequent interfacial hardening during sliding, a previously hypothesized dominant toughening mechanism in nacre. By replicating this mechanism in a scaled-up model synthetic material, we find that it indeed leads to major improvements in energy dissipation. Ultimately, lessons from this investigation may be key to realizing the immense potential of widely pursued nanocomposites.

Identification of deformation mechanism in abalone shells through AFM and digital image correlationIn contrast to man-made materials, nature can produce materials with remarkable mechanical properties from relatively weak constituents. Nacre from seashells is a compelling example: despite being comprised mostly of a fragile ceramic (polygonal calcium carbonate tablets), it exhibits surprisingly high levels of strength and toughness. This performance is the result of an elegant hierarchical microstructure containing a small volume fraction of biopolymers at interfaces. The product is a composite material that is stiff and hard yet surprisingly tough, an essential requirement to protect the seashell from predators. Building a comprehensive understanding of the multi-scale mechanisms that enable this performance represents a critical step toward realizing strong and tough bio-inspired materials. This paper details a nanoscale experimental investigation into the toughening mechanisms in natural nacre and presents a way to translate this understanding to the design of new bioinspired composites. In situ three point bending fracture tests are performed to identify and quantify the toughening mechanisms involved during the fracture of natural nacre at the nanoscale. At the macro and micro scales, previous fracture tests [1] and [2] performed in situ enabled observation of spreading of damage outward from the crack tip. In this study, fracture tests are performed in situ an atomic force microscope to link the larger-scale damage spreading to sliding within the tablet-based microstructure. To quantify the magnitude of sliding and its distribution, images from the in situ AFM fracture tests are analyzed using standard and new algorithms based on digital image correlation techniques which allow for discontinuous displacement fields. Ultimately, this comprehensive methodology provides a framework for broad experimental investigations into the failure mechanisms of bio- and bio-inspired materials.

In-situ AFM Experiments with Discontinuous DIC Applied to Damage Identification in BiomaterialsNatural materials (e.g. nacre, bone, and spider silk) exhibit unique and outstanding mechanical properties. This performance is due to highly evolved hierarchical designs. Building a comprehensive understanding of the multi-scale mechanisms that enable this performance represents a critical step toward realizing strong and tough bio-inspired materials. This paper details a multi-scale experimental investigation into the toughening mechanisms in natural nacre. By applying extended digital image correlation and other image processing techniques, quantitative information is extracted from otherwise prodominantly qualitative experiments. In situ three point bending fracture tests are performed to identify and quantify the toughening mechanisms involved during the fracture of natural nacre across multiple length scales. At the macro and micro scales, fracture tests performed in situ with a macro lens and optical microscope enable observation of spreading of damage outward from the crack tip. This spreading is quantified using an iso-contour technique to assess material toughness. At the nanoscale, fracture tests are performed in situ an atomic force microscope to link the larger-scale damage spreading to sliding within the tablet-based microstructure. To quantify the magnitude of sliding and its distribution, images from the in situ AFM fracture tests are analyzed using new algorithms based on digital image correlation techniques which allow for discontinuous displacement fields. Ultimately, this comprehensive methodology provides a framework for broad experimental investigations into the failure mechanisms of bio- and bio-inspired materials.

Connected projects

Newpores - New Frontiers in Porous Materials

Granted by E2S UPPA, NewPores is an international hub dedicated to the mechanics and physics of porous materials, which intends to answer to new Energy and Environment challenges. This is a joint effort of the group on Geomechanics and Porous Materials (G2MP) of the Laboratoire des Fluides Complexes et leurs Réservoirs at E2S UPPA (France), the Centre for Sustainable Engineering of Geological and Infrastructure Materials (SEGIM) at Northwestern University (USA), the University of Vigo (Spain), the Technical University of Madrid (Spain) and University of Liège (Belgium).

BeCCoH - BÉton et Coulis pour la valorisation de COquilles d’Huîtres (BeCCoH)
OSTRA - Valorisation de coquilles d’huîtres dans des bétons à faible impact environnemental

Financé par la région Nouvelle-Aquitaine et la Communauté d'Agglomération Pays Basque, les projets BeCCoH et OSTRA visent à valoriser les déchets et coproduits coquillers, notamment produits sur le bassin sud d’Arcachon, dans des matériaux cimentaires tels que des bétons ou des coulis de ciment. Ils sont basé sur l’approche performantielle, une démarche innovante permettant de valider des bétons pour des applications spécifiques lorsque la norme NF EN 206-1, qui encadre la production de béton de construction en France, ne s’applique pas.

NacreWell - On the evaluation of Oyster and Nacre as high performance cement-based grouts for geothermal well cementation

Well cementation is used to mechanically link tubing to geological formation and it performs a crucial role to avoid mass transfers between the different geological layers during production. Considering the critical role cement grouts play in order to achieve a well integrity, there is the need to provide an ideal cement grout, which possesses high strength but low ductility and density, which can not be achieved by the classical synthetic materials. Some natural materials like oyster and nacre possess super mechanical performance that may help improve the performance of the grout. This project aims at incorporating oyster or nacre in cements grout formulation in order to increase their performance and decrease their environmental impact.