Sustainable site clean-up from megaprojects: Lessons from London 2012

The London 2012 Olympic and Paralympic Games are considered to have been a great success for the UK. In building the Olympic Park, another great achievement was the clean-up and reuse of a large area of contaminated land. A remediation project of this size would typically take 5 to 15 years to complete, but the project team completed the remediation work in less than 3 years. This study provides an in-depth examination of the remediation practices at the site, mainly from the perspective of sustainable construction. Data were collected from multiple sources, including project files, publications by various government agencies and non-governmental organisations, as well as qualitative interviews with project team members. The paper first presents a review of brownfield redevelopment and sustainable remediation literature. Sustainability initiatives and achievements in the Olympic Park site remediation project are summarised and discussed. These mainly included suitable remediation strategies, recycling and reuse of contaminated soil by using soil washing and innovative in situ remediation of contaminated groundwater through bioremediation. The paper identifies a number of challenges and lessons learned regarding brownfield remediation in megaprojects, which warrant further technological development and appropriate policy actions to address. Funding for this research was provided by the Cambridge International Scholarships Scheme (#10191612) which is gratefully acknowledged.This is the final published version. It first appeared from ICE Publishing at http://www.icevirtuallibrary.com/doi/10.1680/ensu.14.0002

A holistic approach to the environmental evaluation of food waste prevention

The environmental evaluation of food waste prevention is considered a challenging task due to the globalised nature of the food supply chain and the limitations of existing evaluation tools. The most significant of these is the rebound effect: the associated environmental burdens of substitutive consumption that arises as a result of economic savings made from food waste prevention. This study introduces a holistic approach to addressing these challenges, with a focus on greenhouse gas (GHG) emissions from household food waste in the UK. It uses a hybrid life-cycle assessment model coupled with a highly detailed multi-regional environmentally extended input output analysis to capture environmental impacts across the global food supply chain. The study also takes into consideration the rebound effect, which was modelled using a linear specification of an almost ideal demand system. The study finds that food waste prevention could lead to substantial reductions in GHG emissions in the order of 706-896 kg CO$_2$-eq. per tonne of food waste, with most of these savings (78%) occurring as a result of avoided food production overseas. The rebound effect may however reduce such GHG savings by up to 60%. These findings provide a deeper insight into our understanding of the environmental impacts of food waste prevention: the study demonstrates the need to adopt a holistic approach when developing food waste prevention policies in order to mitigate the rebound effect and highlight the importance of increasing efficiency across the global food supply chain, particularly in developing countries.IDB Cambridge International Scholarship, Biotechnology and Biological Sciences Research Council (Grant ID: BB/J014540/1

Polymeric microcapsules with switchable mechanical properties for self-healing concrete: synthesis, characterisation and proof of concept

Microcapsules, with sodium silicate solution as core, were produced using complex coacervation in a double, oil-in-water-in oil, emulsion system. The shell material was a gelatin–acacia gum crosslinked coacervate and the produced microcapsules had diameters ranging from 300 to 700 μm. The shell material designed with switchable mechanical properties. When it is hydrated exhibits soft and ‘rubbery’ behaviour and, when dried, transitions to a stiff and ‘glassy’ material. The microcapsules survived drying and rehydrating cycles and preserved their structural integrity when exposed to highly alkaline solutions that mimic the pH environment of concrete. Microscopy revealed that the shell thickness of the microcapsules varies across their perimeter from 5 to 20 μm. Thermal analysis showed that the produced microcapsules were very stable up to 190 °C. Proof of concept investigation has demonstrated that the microcapsules successfully survive and function when exposed to a cement-based matrix. Observations showed that the microcapsules survive mixing with cement and rupture successfully upon crack formation releasing the encapsulated sodium silicate solution.Financial support from the Engineering and Physical Sciences Research Council (EPSRC—United Kingdom) for this study (Project Ref. EP/K026631/1—‘Materials for Life’) is gratefully acknowledged

A novel membrane emulsification technique for microencapsulation in self-healing concrete: Development and proof of concept

Abstract Membrane emulsification is a promising new technique that can be deployed as a scalable modular conduit for the consistent and continuous production of single and complex emulsions. This work reports on the development of a manufacturing platform based on membrane emulsification for the first time for microcapsule-based self-healing cementitious materials. The feasibility of single and double emulsion production with wall formation as a secondary step through UV radical polymerisation was explored using a discrete membrane emulsification dispersion cell. The operational parameters (pressure, dispersed phase flux, temperature, shear rate) were established for the specific phase characteristics (viscosity, density, interfacial tension) to achieve control of emulsion droplets and maintain a high encapsulation of core content (high payload). Microcapsules with sodium silicate core and an average diameter of ∼130 μm were produced. Microcapsules were shown to achieve high payload (∼89%). Moreover their thermal stability was characterised and their release performance in the cementitious matrix established. The results demonstrated the capability of membrane emulsification to produce microcapsules with an aqueous core for use in self-healing of cementitious materials.</jats:p

Centrifuge model testing for pile foundation reuse

With continuous development in the urban environment the ground is becoming more and more congested with redundant foundations. The underground development of services and infrastructure already restricts the location of new building foundations and the redundant foundations only add to this problem. This paper describes how existing single pile foundations in overconsolidated clay are likely to behave when their loading conditions are changed by un-loading caused by demolition and subsequent re-loading from a new development. The influence of any new foundations on the existing foundations is also described. Experimental data were obtained from a series of centrifuge model tests undertaken at 60g in which a number of different geometries of novel pile groups were modelled. Model tests included comparison of the behaviour of bored piles when supplemented with mini-pile groups

Addressing the need for standardization of test methods for self-healing concrete: an inter-laboratory study on concrete with macrocapsules.

Development and commercialization of self-healing concrete is hampered due to a lack of standardized test methods. Six inter-laboratory testing programs are being executed by the EU COST action SARCOS, each focusing on test methods for a specific self-healing technique. This paper reports on the comparison of tests for mortar and concrete specimens with polyurethane encapsulated in glass macrocapsules. First, the pre-cracking method was analysed: mortar specimens were cracked in a three-point bending test followed by an active crack width control technique to restrain the crack width up to a predefined value, while the concrete specimens were cracked in a three-point bending setup with a displacement-controlled loading system. Microscopic measurements showed that with the application of the active control technique almost all crack widths were within a narrow predefined range. Conversely, for the concrete specimens the variation on the crack width was higher. After pre-cracking, the self-healing effect was characterized via durability tests: the mortar specimens were tested in a water permeability test and the spread of the healing agent on the crack surfaces was determined, while the concrete specimens were subjected to two capillary water absorption tests, executed with a different type of waterproofing applied on the zone around the crack. The quality of the waterproofing was found to be important, as different results were obtained in each absorption test. For the permeability test, 4 out of 6 labs obtained a comparable flow rate for the reference specimens, yet all 6 labs obtained comparable sealing efficiencies, highlighting the potential for further standardization

Large Scale Application of Self-Healing Concrete: Design, Construction, and Testing

Materials for Life (M4L) was a 3 year, EPSRC funded, research project carried out by the Universities of Cardiff, Bath and Cambridge to investigate the development of self-healing cementitious construction materials. This paper describes the UK's first site trial of self-healing concrete, which was the culmination of that project. The trial comprised the in-situ construction of five concrete panels using a range of self-healing technologies within the site compound of the A465 Heads of the Valleys Highway upgrading project. Four self-healing techniques were used both individually and in combination with one another. They were: (i) the use of microcapsules developed by the University of Cambridge, in collaboration with industry, containing mineral healing agents, (ii) bacterial healing using the expertise developed at Bath University, (iii) the use of a shape memory polymer (SMP) based system for crack closure and (iv) the delivery of a mineral healing agent through a vascular flow network. Both of the latter, (iii) and (iv), were the product of research undertaken at Cardiff University. This paper describes the design, construction, testing, and monitoring of these trial panels and presents the primary findings of the exercise. The challenges that had to be overcome to incorporate these self-healing techniques into full-scale structures on a live construction site are highlighted, the impact of the different techniques on the behavior of the panels when subject to loading is presented and the ability of the techniques used to heal the cracks that were generated is discussed.The work reported in this paper was carried out as part of the EPSRC funded project Materials for Life (M4L), reference EP/K026631/1 and supported with PhD studentship funding from Costain Group PLC

Non-Invasive Mapping of the Gastrointestinal Microbiota Identifies Children with Inflammatory Bowel Disease

Background: Pediatric inflammatory bowel disease (IBD) is challenging to diagnose because of the non-specificity of symptoms; an unequivocal diagnosis can only be made using colonoscopy, which clinicians are reluctant to recommend for children. Diagnosis of pediatric IBD is therefore frequently delayed, leading to inappropriate treatment plans and poor outcomes. We investigated the use of 16S rRNA sequencing of fecal samples and new analytical methods to assess differences in the microbiota of children with IBD and other gastrointestinal disorders. Methodology/Principal Findings: We applied synthetic learning in microbial ecology (SLiME) analysis to 16S sequencing data obtained from i) published surveys of microbiota diversity in IBD and ii) fecal samples from 91 children and young adults who were treated in the gastroenterology program of Children’s Hospital (Boston, USA). The developed method accurately distinguished control samples from those of patients with IBD; the area under the receiver-operating-characteristic curve (AUC) value was 0.83 (corresponding to 80.3% sensitivity and 69.7% specificity at a set threshold). The accuracy was maintained among data sets collected by different sampling and sequencing methods. The method identified taxa associated with disease states and distinguished patients with Crohn’s disease from those with ulcerative colitis with reasonable accuracy. The findings were validated using samples from an additional group of 68 patients; the validation test identified patients with IBD with an AUC value of 0.84 (e.g. 92% sensitivity, 58.5% specificity). Conclusions/Significance: Microbiome-based diagnostics can distinguish pediatric patients with IBD from patients with similar symptoms. Although this test can not replace endoscopy and histological examination as diagnostic tools, classification based on microbial diversity is an effective complementary technique for IBD detection in pediatric patients.Natural Sciences and Engineering Research Council of Canada (Award NSERC PGS D)National Institutes of Health (U.S.) (1-R21-A1084032-01A1