ORCID Profile
0000-0001-9124-9079
Current Organisations
University of Western Australia
,
The University of Edinburgh
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Publisher: Canadian Science Publishing
Date: 04-2013
Abstract: Several models have been suggested to link a soil's pore-size distribution to its retention properties. This paper presents a method that builds on previous techniques by incorporating porosity and particles of different sizes, shapes, and separation distances to predict soil water retention properties. Mechanisms are suggested for the determination of both the main drying and wetting paths, which incorporate an adsorbed water phase and retention hysteresis. Predicted results are then compared with measured retention data to validate the model and to provide a foundation for discussing the validity and limitations of using pore-size distributions to predict retention properties.
Publisher: Thomas Telford Ltd.
Date: 03-2016
Abstract: Tailings storage facilities (TSFs) are manmade geotechnical structures usually comprising a perimeter embankment, fill material (the tailings) and a water-level control system. The key issues often raised in TSF operation are uncertainties surrounding likely seepage to the environment and accurate prediction of seepage surfaces for input into stability assessment. Critically, TSFs are much more complex than the current numerical models conventionally assumed. This paper presents techniques for investigating steady-state and drawdown seepage behaviour of TSF embankments using a fixed-beam geotechnical centrifuge. The development of experimental equipment for centrifuge testing is described and novel methods to characterise model materials preliminarily, using a ‘desktop’ centrifuge, is presented. Good agreement is found between experimental results from the fixed-beam centrifuge and those predicted by the GeoStudio SEEP/W software package for steady-state and drawdown conditions at all tested hydraulic gradients.
Publisher: CRC Press
Date: 29-01-2015
DOI: 10.1201/B18046
Publisher: EDP Sciences
Date: 2016
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 07-2021
Publisher: CRC Press
Date: 26-08-2011
DOI: 10.1201/B10526-11
Publisher: Society of Antiquaries of Scotland
Date: 30-11-2022
Abstract: Excavation of a well-preserved stretch of the r art of the Antonine Wall east of Watling Lodge, at Laurieston, allowed for the first micromorphological study of its earthen building materials. This revealed that the r art core, as well as the cheeks, were constructed in well layered courses of turf blocks – but sourced from different grasslands. The evidence differs from macroscopic observations made at other sections in this area where the r art material had been interpreted as representing a loose earth core with clay cheeks. Our results show that even when the characteristic striped sections indicative of turf are not visible in the field, thin-section analysis can confirm the use of intact soil blocks with the remains of grassed surfaces. It now seems possible that the visible variation between materials in the eastern and western sectors of the Antonine Wall may simply be due to different types of turf used, varying in subsoil composition and topsoil formation, and representing differences in landscape management and survival of vegetation. Combined with macroscopic field recording to identify Roman building practices, our analysis of this section at Laurieston also shows the care that was taken to construct a level, well-draining base for the r art to avoid slumping and moisture build-up. Further excavations and thin-section analysis elsewhere along the Wall are now needed to confirm whether turf was more extensively used than so far anticipated for the eastern sector and whether the Antonine Wall could possibly have been built completely of turf. Such conclusions would suggest a much more standardised construction process and more extensive grassland exploitation than considered up until now. While our results demonstrate the importance of micromorphological analysis for understanding this earthen UNESCO World Heritage site, our interdisciplinary approach may also have wider relevance for research on linear earthworks in different geographical and chronological settings.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 09-01-2013
Publisher: Thomas Telford Ltd.
Date: 05-2018
Abstract: Rammed earth (RE) is a venerable construction technique, gaining attention today owing to its environmental and sustainable qualities. A key obstacle to its wider adoption is a lack of strength characterisation methods to aid in design and conservation. Research over the past decade has demonstrated that suction is the key mechanism behind strength and strength gain. As suction changes with the building's environment, being able to predict strength changes with suction is essential for practitioners and conservators alike. This paper presents a method for predicting RE strengths based on the extended Mohr–Coulomb (EMC) framework. Construction of an EMC failure envelope in the residual suction range is discussed and the use of a planar envelope is justified. Unconfined compression and indirect tensile tests on two RE soils are used to construct this envelope and methods to predict strengths from it are derived. Excellent agreement between measured and predicted strengths is also found for available data in the literature. Simplifications are identified to adapt the developed technique to suit RE practice and a suitable experimental procedure is outlined. Finally, the revised experimental procedure is employed at an existing RE construction facility to successfully predict strengths of a compacted Californian sandy loam.
Publisher: Canadian Science Publishing
Date: 05-2014
Abstract: Current guidelines suggest that stabilized rammed earth materials be compacted at their optimum water content to achieve their maximum strength. Although this is true for traditional rammed earth, there is no evidence that this procedure should also be used for cement-stabilized rammed earth. Furthermore, the water content used at compaction is usually difficult to control on a construction site, so that material might be compacted at water contents other than the optimum. In this paper, a novel experimental programme is presented in which the effect of compaction water content on the unconfined compressive strength of crushed limestone stabilized to 5% Portland cement content is investigated for a range of curing periods. Freeze drying of specimens was used to arrest cement hydration to determine the evolution of hydrated cement content. Scanning electron microscope (SEM) analysis was used to identify differences between the final material microstructures. Results are discussed demonstrating the intimate link between the amount of hydrated cement, material microstructure, and compressive strength.
Publisher: ASTM International
Date: 2011
DOI: 10.1520/GTJ103517
Publisher: Thomas Telford Ltd.
Date: 02-2019
Publisher: CRC Press
Date: 29-01-2015
DOI: 10.1201/B18046-15
Publisher: Elsevier BV
Date: 07-2017
Publisher: Informa UK Limited
Date: 14-12-2016
Publisher: EDP Sciences
Date: 2023
DOI: 10.1051/E3SCONF/202338205002
Abstract: The 1952 CSIRO accelerated erosion test was the first to appraise the quality and potential longevity of earthen construction materials. The test measures the depth of erosion resulting from a spray of water delivered at a set pressure and distance from a nozzle of controlled geometry. The test has remained popular, due to its simplicity, and forms the basis of the design for durability in the current New Zealand earthen construction standards (and their derivatives). However, it is now recognised that the accelerated erosion test does not capture the full range of exposure conditions likely to affect an earthen structure during its lifetime. As such, academics and practitioners have suggested variations to the test, to reproduce erosion which is observed in the field. However, this makes it difficult to compare the results of one test to another, and so prevents any standardised material assessment. As earthen construction materials grow in interest in the unsaturated soils community, it is becoming necessary to understand and explore the limitations of these materials beyond their hydromechanical properties and to compare results between investigations fairly. This paper presents the concept of a ‘generic’ accelerated erosion test method and examines the effect of the spray pressure and spray distance on the erosive force delivered to the test specimen, to understand how these variables could be normalised. The generic method, when developed, will remove the strict restrictions of the original apparatus, making the test universally accessible.
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 06-2017
Publisher: Thomas Telford Ltd.
Date: 12-2015
Abstract: Flocculating agents can be introduced to soils through a number of natural or anthropogenic processes. This paper investigates the effect of flocculant addition (aqueous calcium chloride (CaCl 2 )) on the tensile strengths of two soils of differing flocculation susceptibility. Tensile strengths were found using the Brazilian (direct splitting) test for a range of suction values. A decrease in tensile strength was found for a soil with high clay content, which was consistent with previous findings in the literature. However, the strength of the soil with lower clay content unexpectedly increased. Results were interpreted using the extended Mohr–Coulomb (EMC) yield criterion fitted to data above the residual suction value. Changes in EMC parameters were used to infer changes in material behaviour on calcium chloride addition. Results have important implications for the design of geotechnical structures, for ex le engineered cover systems, exposed to flocculating conditions.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Thomas Telford Ltd.
Date: 10-2016
Abstract: In February 2015, the University of Western Australia organised the First International Conference on Rammed Earth Construction. The event was a major success with participants from 11 countries. The participants were representatives from the research (scientists, professors, students) and industry worlds (engineers, architects, builders). The conference provided the unique opportunity to present recent advances in rammed earth research, innovative construction practices and sustainable projects in different countries. It also provided the opportunity to discuss the current issues experienced by the rammed earth industry around the world and to create collaborations between research institutions. This paper presents a summary of the discussions held at the forums of the event. It aims to disseminate the priority research topics identified at the conference and to increase awareness of the difficulties currently experienced by the rammed earth industry and by academia.
Publisher: EDP Sciences
Date: 2023
DOI: 10.1051/E3SCONF/202338217008
Abstract: Turf is not a material frequently associated with construction. However, as a cheap, easily available, and versatile material it was used in antiquity (and has been used in various contexts since) to form unit-based and mass walls, embankments, and r arts. Some of the best-preserved evidence for historical turf use comes from the Roman period, when it was a mainstay of military construction, being widely used in forts (e.g. along the Rhine and in Britain) and large-scale linear earthworks, most notably thewalls of Hadrian (northern England) and Antoninus Pius (central Scotland). To our knowledge, turf has never been examined as a construction material its interest has, until now, been restricted to the soil and agricultural sciences and sports engineering. This paper presents the first exploration of turf water retention properties, assessed to understand whether turf behaviour can be collated with that of more traditionalearthen materials, for ex le cob or rammed earth. Tensiometer and psychrometer methods were used to estimate the water retention curves of turf, representative of that used for construction, harvested from two sites near Crieff, Scotland. The obtained data were analysed in terms of unimodal type functions to understand qualities of the full range of the soil water retention curve for Scottish turf. This work supports a larger project examining how engineering materials principles can explain ancient construction practices. In so doing, we will be well positioned to reintroduce this low-carbon material to the modern construction market.
Publisher: Springer Berlin Heidelberg
Date: 2012
Publisher: The Royal Society
Date: 04-08-2021
Abstract: The need for a vast quantity of new buildings to address the increase in population and living standards is opposed to the need for tackling global warming and the decline in bio ersity. To overcome this twofold challenge, there is a need to move towards a more circular economy by widely using a combination of alternative low-carbon construction materials, alternative technologies and practices. Soils or earth were widely used by builders before World War II, as a primary resource to manufacture materials and structures of vernacular architecture. Centuries of empirical practices have led to a variety of techniques to implement earth, known as rammed earth, cob and adobe masonry among others. Earth refers to local soil with a variable composition but at least containing a small percentage of clay that would simply solidify by drying without any baking. This paper discusses why and how earth naturally embeds high-tech properties for sustainable construction. Then the potential of earth to contribute to addressing the global challenge of modern architecture and the need to re-think building practices is also explored. The current obstacles against the development of earthen architecture are examined through a survey of current earth building practitioners in Western Europe. A literature review revealed that, surprisingly, only technical barriers are being addressed by the scientific community two-thirds of the actual barriers identified by the interviewees are not within the technical field and are almost entirely neglected in the scientific literature, which may explain why earthen architecture is still a niche market despite embodying all the attributes of the best construction material to tackle the current climate and economic crisis. This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 02-2014
Publisher: Springer Science and Business Media LLC
Date: 14-05-2011
Publisher: EDP Sciences
Date: 2016
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 10-2018
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Christopher Beckett.