Macrostructural changes in compacted earthen construction materials under loading

Beckett, Chris; Hall, Matthew; Augarde, Charles E.

doi:10.1007/s11440-012-0203-6

Cited by 24 publications

(16 citation statements)

References 59 publications

(4 reference statements)

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“…Hence, the present work was performed as part of a larger investigation into the feasibility of using granulated clay within tablet formulations [Asare-Addo et al 2014]. Nevertheless, the compaction behaviour of clays is also important in many other situations; examples include the manufacture of ceramics [Rahman 2003, Pizette et al 2013; in building materials [Morel et al 2007, Villamizar et al 2012, Beckett et al 2013; in geology, where compacted clay layers can trap hydrocarbon deposits [Vanorio et al 2003, Mondol et al2007; in soil mechanics, where compaction can affect the porosity of agricultural soil [Berisso et al 2012, Romero 2013 and the behaviour of foundations [Kuklic 2011, Prakash et al 2013; as barrier materials for the storage of nuclear waste, where compacted clay gives low permeability [Tien et al 2004, Ito 2006, Villar and Lloret 2008, Baille et al 2010, Ye et al 2012, Villar et al 2012.…”

mentioning

confidence: 99%

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Laity

Asare-Addo

Sweeney

et al. 2015

Applied Clay Science

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ABSTRACT:The compaction behaviour of a commercial granulated clay (magnesium aluminium smectite, gMgSm) was investigated using macroscopic pressure-density measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray microtomography (XµT) and small-angle X-ray scattering (SAXS). This material was studied as a potential compaction excipient for pharmaceutical tabletting, but also as a model system demonstrating the capabilities of SAXS for investigating compaction in other situations.Bulk compaction measurements showed that the gMgSm was more difficult to compact than polymeric pharmaceutical excipients such as spheronised microcrystalline cellulose (sMCC), corresponding to harder granules. Moreover, in spite of using lubrication (magnesium stearate) on the tooling surfaces, rather high ejection forces were observed, which may cause problems during commercial tabletting, requiring further amelioration. Although the compacted gMgSm specimens were more porous, however, they still exhibited acceptable cohesive strengths, comparable to sMCC. Hence, there may be scope for using granular clay as one component of a tabletting formulation.Following principles established in previous work, SAXS revealed information concerning the intragranular structure of the gMgSm and its response to compaction. The results showed that little compression of the intragranular morphology occurred below a relative density of 0·6, suggesting that granule rearrangements or fragmentation were the dominant mechanisms during this stage. By contrast, granule deformation became considerably more important at higher relative density, which also coincided with a significant increase in the cohesive strength of compacted specimens.Spatially-resolved SAXS data was also used to investigate local variations in compaction behaviour within specimens of different shape. The results revealed the expected patterns of density variations within flat-faced cylindrical specimens. Significant variations in density, the magnitude of compressive strain and principal strain direction were also revealed in the vicinity of a debossed feature (a diametral notch) and within biconvex specimens. The variations in compaction around the debossed notch, with a small region of high Clay compaction SAXS -revised PRL 2015-01-03

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mentioning

confidence: 99%

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Laity

Asare-Addo

Sweeney

et al. 2015

Applied Clay Science

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“…In that work, specimens were uniaxially loaded to either 25 or 85% of their predetermined failure load prior to scanning. This work expands on that study by investigating macrostructural changes in specimens progressively loaded to failure, not possible in the work of Beckett et al (2013) due to the need to transport specimens between loading and scanning sites. A SkyScan1174 compact micro-CT scanner (SS1174), on loan from the UK EPSRC, was used to investigate the compressive loading behaviour of RE specimens.…”

Section: Development Of Xrct Scanning Methodsmentioning

confidence: 97%

“…Macrostructural changes in RE materials under loading were investigated by Beckett et al (2013). In that work, specimens were uniaxially loaded to either 25 or 85% of their predetermined failure load prior to scanning.…”

Section: Development Of Xrct Scanning Methodsmentioning

confidence: 99%

“…Over the past ten years technological improvements to XRCT have seen the increasing use of the technique in the fields of soil science (Helliwell et al 2013) and engineering geology (Jacobs & Cnudde 2009) although the use of XRCT in unsaturated soil research has been limited by the spatial resolution limiting the visualisation of separate particles and associated voids (Oda et al 2004). However, in the last few years, XRCT has been applied to the observation of local deformation processes in sand (Hall et al 2010), the mesopore size distribution of cement stabilised soils , and structural changes of unsaturated soil under loading (Beckett et al 2013). …”

Section: Use Of Xrct In Scanning Soil Samplesmentioning

confidence: 99%

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The use of XRCT to investigate highly unsaturated soil mixtures

Smith¹,

Augarde²,

Beckett³

2014

Unsaturated Soils: Research &Amp; Applications

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“…Beckett et al [4] used XRCT to observe the changes to the macrostructure of rammed earth following compressive loading and observed how compaction during manufacture affects the macrostructure within individual layers of rammed earth. Due to limitations on sample size, only the inter-aggregate soil matrix, formed of clay and sand particles, was investigated.…”

Section: Internal Structure Of Soil Based Construction Materialsmentioning

confidence: 99%

Sample size choices for XRCT scanning of highly unsaturated soil mixtures

Smith

Augarde

2016

E3S Web Conf.

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Abstract. Highly unsaturated soil mixtures (clay, sand and gravel) are used as building materials in many parts of the world, and there is increasing interest in understanding their mechanical and hydraulic behaviour. In the laboratory, xray computed tomography (XRCT) is becoming more widely used to investigate the microstructures of soils, however a crucial issue for such investigations is the choice of sample size, especially concerning the scanning of soil mixtures where there will be a range of particle and void sizes. In this paper we present a discussion (centred around a new set of XRCT scans) on sample sizing for scanning of samples comprising soil mixtures, where a balance has to be made between realistic representation of the soil components and the desire for high resolution scanning, We also comment on the appropriateness of differing sample sizes in comparison to sample sizes used for other geotechnical testing. Void size distributions for the samples are presented and from these some hypotheses are made as to the roles of inter-and intra-aggregate voids in the mechanical behaviour of highly unsaturated soils.

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Macrostructural changes in compacted earthen construction materials under loading

Cited by 24 publications

References 59 publications

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

The use of XRCT to investigate highly unsaturated soil mixtures

Sample size choices for XRCT scanning of highly unsaturated soil mixtures

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