Under Pressure: A Laboratory Investigation into the Effects of Mechanical Loading on Charred Organic Matter in Archaeological Sites

Ngan-Tillard, D.J.M.; Dijkstra, Jelke; Verwaal, W.; Mulder, A.; Huisman, Hans; Müller, Axel

doi:10.1080/13505033.2015.1124179

Cited by 3 publications

(6 citation statements)

References 12 publications

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“…Specimens are either scanned only after testing, before and after testing or, when compressed in a mould transparent to X-rays, at several stages of loading (Ngan-Tillard, et al, 2015). For specimens that are only scanned after testing, comparison with virgin specimens is needed.…”

Section: Methodsmentioning

confidence: 99%

“…So far, our laboratory simulations on undisturbed soils have been limited to the one-dimensional (1D) compression conditions that prevail underneath the central part of the embankment, away from the toes. The tests can be carried out by compressing axially thin soil cylinders while restraining their lateral extension using traditional load steps or constant displacement rate oedometers (Ngan-Tillard, et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

“…Various failure mechanisms ranging from brittle tensile failure to particle indentation and progressive crushing were observed on micro-CT scans acquired at various loading phases. The macroscopic yield stress derived from the breaking point in the semi-logarithmic strain-stress oedometric curves (see Figure 3 in Ngan-Tillard, et al, 2015) was found to be a function of particle strength, size, shape, behaviour, as well as assemblage porosity. The yield stress was often ill-defined with a lowest value for the weakest assemblage of about 45 kN/m 2 (= 2.5 m of sand) assuming a unit weight of 18 kN/m 3 for sand to translate stress to height of sand embankment placed on the ground surface.…”

Section: Tests On Assemblages Of Charred Organic Ecofactsmentioning

confidence: 99%

“…A first series of tests (Ngan-Tillard, et al, 2015) has been conducted on reconstituted assemblages of charred ecofacts (wheat and oat grains, wood fragments, and hazelnut shell fragments). The particles had either been recovered from Dutch archaeological sites or were replicas of these charred materials.…”

Section: Tests On Assemblages Of Charred Organic Ecofactsmentioning

confidence: 99%

“…The performance of the numerical simulations is evaluated. Our laboratory tools have already been presented for pure assemblages of charred organic particles and sand seeded with charred organic particles (Ngan-Tillard, et al, 2015) and for organic soils recovered at our test sites (Ngan-Tillard, et al, 2014). Hereby, we give a brief overview of the ability of our tools at predicting loss of archaeological value.…”

Section: Introductionmentioning

confidence: 99%

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Tools for Predicting Damage to Archaeological Sites Caused by One-Dimensional Loading

Ngan-Tillard

Brinkgreve

Huisman

et al. 2016

Conservation and Management of Archaeological Sites

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Tools are developed to predict damage to archaeological remains caused by the construction of line infrastructure on soft soil. They are based on numerical modelling and laboratory testing supported by X-ray microcomputed tomographic observations, and micromorphological analyses of thin sections. They have been validated for one-dimensional (1D) loading at two sites in the Netherlands where soil has been placed on top of organic layers rich in ecofacts and overlaying Pleistocene sands.Numerical prediction of the deformation of soft layers underneath an embankment remains a challenge for geo-technical engineers. Errors on surface settlement prediction reach ±15% of the measured total settlement. Laboratory observations show that vulnerable artefacts can get crushed when packed loosely in pure assemblies under 1D loading equivalent to less than 5 m of sand. Fragmentation is assimilated to loss of archaeological value as it compromises recovery during sieving. Embedment in a sandy or a very compressible organic matrix has a beneficial effect on the resistance of ecofacts. Embedded ecofacts can resist a load of more than 12 m of sand. Flattening and re-orientation of soft plant remains occur during 1D loading without microscopic damage of tissues.keywords wetland archaeology, one-dimensional compression, damage, X-ray microcomputed tomography

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Tests On Assemblages Of Charred Organic Ecofactsmentioning

confidence: 99%

Section: Tests On Assemblages Of Charred Organic Ecofactsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tools for Predicting Damage to Archaeological Sites Caused by One-Dimensional Loading

Ngan-Tillard

Brinkgreve

Huisman

et al. 2016

Conservation and Management of Archaeological Sites

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Over the rainbow? Micro-CT scanning to non-destructively study Roman and early medieval glass bead manufacture

Ngan-Tillard

Huisman

Corbella

et al. 2018

Journal of Archaeological Science

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A preservação de restos arqueobotânicos e o processo de análise por microtomografia de raios X

Calo

Rizzutto

2023

Rev. Mus. Arqueol. Etnol.

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O uso de microtomografias de raios X para o estudo de restos macroscópicos de plantas recuperadas em sítios arqueológicos é uma prática relativamente recente em Arqueologia. No entanto, a técnica possui amplo espectro de aplicações em áreas de pesquisa muito diversas. Os diferentes trabalhos relacionados com a aplicação apontam a não destrutividade dos procedimentos microtomográficos como um de seus atributos relevantes, juntamente com a alta qualidade de discriminação das imagens tridimensionais geradas no processo. Este trabalho explora a importância dessa característica da microtomografia em relação a diferentes aspectos do estudo e da preservação dos macrorrestos arqueobotânicos. Ao preservar a integridade e habilitar a reanálise dos objetos examinados, a microtomografia de raios X permite otimizar a qualidade dos resultados e expandir a gama de técnicas analíticas aplicadas em seu estudo. Essa vantagem manifesta-se tanto na pesquisa em curso como naquelas que podem ser desenvolvidas no futuro sobre os mesmos objetos, usando técnicas e abordagens novas ou melhoradas. Além da preservação do objeto físico, a microtomografia providencia réplicas virtuais tridimensionais que podem ser utilizadas com finalidade analítica ou como respaldo da informação gerada. Aliás, esses modelos digitais apresentam grande adaptabilidade aos mecanismos de compartilhamento e disponibilização de dados de pesquisa, assim como podem ter efeitos notáveis na ênfase do valor visual dos materiais arqueobotânicos.

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Under Pressure: A Laboratory Investigation into the Effects of Mechanical Loading on Charred Organic Matter in Archaeological Sites

Cited by 3 publications

References 12 publications

Tools for Predicting Damage to Archaeological Sites Caused by One-Dimensional Loading

Tools for Predicting Damage to Archaeological Sites Caused by One-Dimensional Loading

Over the rainbow? Micro-CT scanning to non-destructively study Roman and early medieval glass bead manufacture

A preservação de restos arqueobotânicos e o processo de análise por microtomografia de raios X

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