Design and multi-physical properties of a new hybrid hemp-flax composite material

International audienc

Effectiveness of Composite CFRP Confinement on Very Slender Reinforced Concrete Columns

This research work is based on an experimental study resulting from tests carried out on six square-section slender reinforced concrete columns. The columns were confined by single-layer wraps of carbon fiber composites. They were tested under eccentric compression loading, to study the effects of confinement by the carbon fiber composite on resistance loading, rigidity, ductility and slender column behavior in genera

Elément de planchers composites bois-béton léger

Les éléments composites de planchers bois-béton léger connaissent de plus en plus de popularité dans la réhabilitation et dans les constructions neuves des structures de génie civil. En partenariat avec des industriels, nous avons mis au point un procédé de construction de planchers mixtes, composés d'éléments porteurs en bois et d'une chape de béton confectionnée à partir de fibres de bois. Une étude expérimentale conduite sur les matériaux constituant cette mixité et leurs liaisons ainsi que les approches réglementaires nécessaires à leur dimensionnement sont présentées

Direct Observation of Propagating Gigahertz Coherent Guided Acoustic Phonons in Free Standing Single Copper Nanowires

We report on gigahertz acoustic phonon waveguiding in free-standing single copper nanowires studied by femtosecond transient reflectivity measurements. The results are discussed on the basis of the semianalytical resolution of the Pochhammer and Chree equation. The spreading of the generated Gaussian wave packet of two different modes is derived analytically and compared with the observed oscillations of the sample reflectivity. These experiments provide a unique way to independently obtain geometrical and material characterization. This direct observation of coherent guided acoustic phonons in a single nano-object is also the first step toward nanolateral size acoustic transducer and comprehensive studies of the thermal properties of nanowires

The Influence of the Type of Lime on the Hygric Behaviour and Bio-Receptivity of Hemp Lime Composites Used for Rendering Applications in Sustainable New Construction and Repair Works

The benefits of using sustainable building materials are linked not only to the adoption of manufacturing processes that entail reduced pollution, CO2 emissions and energy consumption, but also to the onset of improved performance in the building. In particular, hemp-lime composite shows low shrinkage and high thermal and acoustic insulating properties. However, this material also shows a great ability to absorb water, an aspect that can turn out to be negative for the long-term durability of the building. For this reason, the hygric properties of hemp-based composites need to be studied to ensure the correct use of this material in construction and repair works. The water absorption, drying and transpirability of hemp composites made with aerial (in the form of dry powder and putty) and hydraulic limes were investigated here and related to the microbial growth induced by the water movements within the material. Results show that hemp-natural hydraulic lime mixes exhibit the highest transpirability and drying rate, the lowest water absorption by immersion and capillary uptake and the least intense microbial attack and chromatic change. A microscopical study of the hemp shives also related their great ability to absorb water to the near-irreversible swelling of their structure under dry-wet conditions.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 326983 (NaturALiMe), and the Spanish project MAT-2012-34473 of the Ministerio de Ciencia y Competitividad. Author MB, owner of the CANNABRIC company, had some role in the design and preparation of mortar samples and in the preparation of this manuscript, but did not have any additional role in data collection and analysis

INVESTIGATION ON THE PERFORMANCE AND DURABILITY OF TREATED HEMP CONCRETE WITH LINSEED OIL

International audienceGiven the low mechanical strength, hemp concrete cannot therefore be used as a load bearing material. Hemp concrete principal weakness point is the strength but the lack of information concerning the durability performance of this material can also be an explanation for the professional's reluctance to use bio-based concrete. This study focused on the effects of aggregate treatments, linseed oil and two different binders. The mechanicals performance such as the compressive strength at 7, 14 and 28 days were done. The results shows that with higher density treated samples get a higher strength in compression.. Then hydraulic performance was tested with the capillarity test and highlighted the great decrease of sorption coefficient on treated samples. Finally the durability performance tests included the full water immersion test, and the carbonation test in accelerated chamber. Weathering results are better for treated sample compared to none-treated, which are less absorbent and less destructive for specimens. Treated samples carbonated quicker than no treated ones