Abstract To determine the water vapour permeability of porous building materials, the wet cup and dry cup tests are frequently performed. Those tests have shown to present high discrepancy. The water ...vapour permeability of building materials is an essential parameter to determine the hygrothermal behaviour of the material and its impact on indoor comfort. Several previous studies have aimed to improve the reproducibility of the tests, by improving the protocol, the analysis of the results, notably by taking into account the surface film resistance. Yet, it is commonly accepted with no evidence that this surface film resistance can be neglected for an air velocity above 2 m/s over the cup. This study aims at experimentally testing the influence of either the flow regime or the flow velocity on the robustness of the measured water vapour permeability. For this purpose, two mini wind tunnels were designed to produce a laminar or a turbulent flow above the cups with variable air velocity. Water vapour permeability tests were performed in the tunnels with varying air velocity and flow regime on earth plasters with different compositions. The results have shown that regardless of the air velocity and flow regime, the surface film resistance should not be neglected. Based on the presented results, to reach an optimal repeatability, the use of wind tunnels should be considered as they allow to precisely control the air flow above the samples.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
RationaleEngineered nanomaterials (ENMs) induce groundbreaking impacts by endowing unique properties to materials. However, uncertainties remain on their biological aftereffects. Entrusted by health ...and labour ministries, the French Public Health Institute launched since 2014 the EpiNano epidemiological surveillance program of workers potentially exposed to ENMs. The 2016–2020 national occupational health (OH) action plan inscribed the ENMs topic as of priority, with an enlargement to the construction and civil-engineering (CCE) sector. A scientific consortium was therefore established in order elaborate a standardised methodology to identify ENMs-exposed CCE workers.MethodsA comprehensive, structured PubMed review and web-search of technical documents was undertaken, complemented by in-depth experts’ interviews to collect contextual information regarding CCE nanoproducts.ResultsSeveral methodological challenges were primarily revealed, pertaining primarily to : (i) Demarcating the target population: Involvement of a large number of companies (400,000) of all sizes and activities; Massive delegation to subcontractors; Heterogeneity of socioprofessional categories (from engineers to operators) and occupations (around 22); (ii) Unknown exposures’ circumstances: no CCE nanoproducts inventories neither detailed composition information; Unawareness of CCE actors of nanoproducts’ use; Heterogeneity of ENMs incorporated in various matrices (cement, coatings, paints…) with unknown ENM release/exposure potential; Potentially passive occupational exposures; Myriad of confusion factors with interactions with other risks at workplace; (iii) Capturing and following the eligible population: a complex topic to be addressed with a lot of pedagogy for adhering workers; epidemiological follow-up hampered by high turnovers, duration of construction sites and language barrier. Discussions are ongoing to overcome these methodological challenges. As a first step, an awareness campaign and the establishment of CCE nanoproducts’ inventory will be launched soon.ConclusionsAn increase in CCE nanoproducts’ use is expected in the context of sustainable development and energy saving. This underscores the urgency to implement a specific surveillance system, by circumventing designing complexity.
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BFBNIB, CMK, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
•We present a methodology based on Factor Analysis and MDS for literature reviews.•We introduce the notion of research factor related to the presented methodology.•We summarize the state of the art ...about RE through 5 research factors.•We suggest future multi-disciplinary research directions for RE.
This paper offers an extensive literature review on the field of Resilience Engineering (RE), encompassing 472 contributions, including journal articles, conference proceedings and book chapters. Adopting the numbers of co-citations as a metric of conceptual proximity, this paper details the application of Factor Analysis and Multi-Dimensional Scaling, as groundbreaking means to extract relevant research factors. A temporal analysis in a multi-variate two-dimensional space confirms the significance and relevance of the identified research factors. An in-depth analysis of the five research factors, labeled as the need of RE, RE for modelling, defining and exploring RE, reflecting on RE, RE and improvisation, guides the definition of future research paths and open research questions within the field and across several domains, suggesting the need for multi-disciplinary future studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template ...matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent ...literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis.
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IJS, KILJ, NUK, PNG, UL, UM
The development of value-added materials from by-product of the steel-making process can promotesustainability in construction to move towards a circular economy. The use of Electric Arc Furnace(EAF) ...steel slag as heavyweight coarse aggregate to develop sustainable radiation shielding concretecould provide both technical and economic benefits with less environmental impact. This contributioninvestigates the behaviour at high temperature of a sustainable radiation shielding concrete. Thermalbehaviour of EAF slag concrete was compared to another heavyweight concrete made of barite aggregatesand to a normal-weight concrete. On one hand, the thermal stability of the three different aggregates wasdetermined via simultaneous Thermogravimetry and Differential Scanning Calorimetry analyses andvisual observations after 10 C/min heating. On the other hand, the evolution of thermal conductivityof concretes during heating, the residual mechanical properties and the assessment of potential spallingoccurrence were investigated. Stereo-microscope and Scanning Electron Microscope pictures provideadditional explanations by showing the paste-aggregate interface after heating at 450 C. The results indicatedthat EAF concrete displayed less strength reduction at increasing temperature. This improved behaviouris attributed to both the strong bond between the paste and the aggregates, and the better thermalbehaviour of the EAF slag aggregates compared to barite aggregates.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Over the past three decades, the strengthening and repair of existing civil engineering structures using FRP laminates has attracted a great deal of attention. With the advances in polymer science, ...adhesive bonding has become a common joining technology in these applications. Despite numerous studies that address the short-term behaviour of adhesively bonded FRP/steel joints, uncertainty with respect to long-term performance still remains. This knowledge gap is regarded as a critical barrier, hindering the widespread application of FRPs to strengthen and retrofit steel structures. This paper presents the state of the art in terms of the durability of FRP/steel joints used in civil engineering applications. Important influential factors relating to the durability of adhesively bonded joints are reviewed and different damage mechanisms are discussed. Moreover, related investigations of the combined environmental durability of these joints are critically reviewed and the findings are presented. The paper concludes with a discussion to motivate future research topics, while it is emphasised that the generalisation of the available results is questionable.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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