Hygrothermal effects and moisture kinetics in a bio-based multi-layered wall:Experimental and numerical studies

International audienceA bio-based multi-layered reference wall has been developed within the framework of the European ISOBIO project. One of the key points of this project was to be able to perform proper simulations of the hygrothermal transfers occurring inside such walls. Previous published investigations, also performed in the framework of this project, have demonstrated that the classic assumption of instantaneous equilibrium between local relative humidity and water content according to the sorption isotherm is not relevant for bio-based porous materials, where, in practice, a rather slow kinetics of sorption occurs. The theoretical background developed in this previous study is used here to determine the kinetic constants of the bio-based construction materials and to perform 1D hygrothermal simulations. The kinetics constants are determined thanks to a 1D cylindrical tool based on the local kinetics approach, validated against several experiments of sorption. Then, heat and hygric transfers recorded on a demonstrator building (The HIVE, Wroughton, UK) are analyzed and are simulated using two modeling tools: TMC based on the Künzel approach and TMCKIN based on the local kinetic approach. From the simulations, the local kinetics improves the small timescale RH dynamics. The comparison with measurements performed in the demonstrator confirms the relevance of the local kinetics approach

Updated Iberian archeomagnetic catalogue: new full vector paleosecular variation curve for the last three millennia

In this work, we present 16 directional and 27 intensity high‐quality values from Iberia. Moreover, we have updated the Iberian archeomagnetic catalogue published more than 10 years ago with a considerable increase in the database. This has led to a notable improvement of both temporal and spatial data distribution. A full vector paleosecular variation curve from 1000 BC to 1900 AD has been developed using high‐quality data within a radius of 900 km from Madrid. A hierarchical bootstrap method has been followed for the computation of the curves. The most remarkable feature of the new curves is a notable intensity maximum of about 80 μT around 600 BC, which has not been previously reported for the Iberian Peninsula. We have also analyzed the evolution of the paleofield in Europe for the last three thousand years and conclude that the high maximum intensity values observed around 600 BC in the Iberian Peninsula could respond to the same feature as the Levantine Iron Age Anomaly, after travelling westward through Europe

Development and characterization of thermal insulation materials from renewable resources

International audienc

Hemp-Straw Composites: Thermal and Hygric Performances

International audienc

Mechanical properties of hemp-clay and hemp stabilized clay composites

International audienceThis study aims to develop a new low carbon footprint material using hemp and clay. It investigates the effect of clay stabilization and hemp to binder ratio on mechanical performances. All composites have ductile behavior. Composites with highest hemp to binder ratio show steadily increasing strength with deformation. Hemp stabilized clay composites have better mechanical properties than hemp clay composites. Mechanical properties strongly depend on the hemp to binder ratio. The tensile strength ranges from 0.021 to 0.059 MPa. The compressive strength ranges from 0.39 to 0.68 MPa. The mechanical performance of developed composites meets the requirements of the intended use. © 2017 Elsevier Lt

Development and hygric and thermal characterization of hemp-clay composite

International audienc

Réduction du pouvoir absorbant de chènevottes par traitement imperméabilisant

Le béton de chanvre est utilisé comme matériau de remplissage non porteur associé à une ossature bois. C’est un matériau composite obtenu en mélangeant un liant minéral à base de chaux, du chanvre (chènevottes) et de l’eau. Afin de garantir une bonne mise en œuvre, le béton de chanvre a, en général, un besoin en eau de gâchage nettement supérieur à celui d’un mélange classique granulat/liant. Cette quantité d’eau est de plus liée au process de fabrication. Cette étude vise à montrer l’influence de la chènevotte sur le dosage en eau et à évaluer les effets d’un traitement visant à réduire la capacité d’absorption de la chènevotte tout en préservant au maximum les propriétés qui font du béton de chanvre un bon matériau isolant et perméable. Un banc expérimental est conçu pour réaliser les essais de mouillage. Différents protocoles de traitements par immersion avec un hydrofuge sont testés

Water Transport in Bio-based Porous Materials A Model of Local Kinetics of Sorption—Application to Three Hemp Concretes

International audienc

Le four néolithique à fosse d’accès des « Petits-Clos » à Chartres (Eure-et-Loir) : une attribution chrono-culturelle complexe

National audienc