1,015 Works

Optimisation des propriétés thermiques d’isolants à base de fibres de bois

Pierre Vignon, Jérôme Moreau, Christine Delisée, Mickael Lecourt, Huyen Tran & Thierry Sanguina
Les matériaux à base de fibres de bois sont obtenus à partir de différents procédés qui déterminent la densité des produits et leurs applications. L’un d’entre eux, issu de l’industrie textile et adapté aux fibres de bois, permet la conception de réseaux 3D enchevêtrés de forte épaisseur et de faible densité. Dans le cadre d’un projet, financé par l’ADEME, l’optimisation de ce procédé et des matériaux ainsi fabriqués est actuellement en cours. L’accent est mis,...

Effet du traitement sur les propriétés thermomécaniques et hydriques de la paille céréalière utilisée pour un matériau d’isolation thermique

Naima Belayachi, Dashnor Hoxha & Brahim Ismail
L’objectif de ce travail est d’étudier l’influence de deux traitements sur le comportement de la paille céréalière en vue de son utilisation dans l’élaboration d’un bio-composite destiné à l’isolation thermique des bâtiments. Le papier présente les essais réalisés sur deux variétés de paille blé et orge, comprenant les essais d’absorption d’eau après différents temps d’immersion, les essais thermomécaniques, et les analyses ATG-DSC pour l’étude de la dégradation ou décomposition thermique. L’exploitation des résultats de dilatation...

Investigation of performance tests using bio-derived/chemical additives

J. Podolsky, A. Buss, R. C. Williams & E. Cochran
An industry wide emphasis on sustainable asphalt practices has given rise to increasing use of warm mix asphalt technologies. WMA reduces both binder viscosity and mixing and compaction temperatures by 20-55°C during the asphalt mix production and laydown process. This research investigates several bio-derived WMA additives that act as chemical modifiers with surfactant properties. Two established additives derived from the forest products industry are studied as well as a WMA additive in development that is...

Rheological and mechanical behavior of earth materials / starch mixes

G. Alhaik, M. Ferreira, V. Dubois, E. Wirquin, S. Tilloy, E. Monflier & G. Aouad
This research work highlights a new approach in the sector of building materials based on bio resources. An experimental investigation was conducted in order to study the rheological and mechanical behavior of earth/starch mixes. In this study, two types of earth materials have been studied: quarry fines and a model material which was kaolinite. For starches, two categories have been used: native and derivative. Starch with a chemical modification has also been studied. The earth/starch...

Effects of seashell aggregates in concrete properties

B. Gonzalez, D. Carro, F. Martínez-Abella, C. Martínez & S. Seara-Paz
In this project the use of mussel shell as fine and coarse aggregate in concrete is studied. Two different conventional concretes were designed, a non-structural concrete (NSC) and a plain structural one (SC). Then, the conventional fine and coarse aggregate was partially replaced with seashell. Initially, each size fraction (fine or coarse) was replaced separately using four substitution rates (25%, 50%, 75% and 100%). Finally, two low percentages (5% and 12.5%) were chosen to replace...

Investigating the strain rate-dependent compressive properties of fiber-reinforced soy-based polyurethane foams

N. Obaid, M. Kortschot & M. Sain
Although conventional polyurethane foams are used in several applications; they are produced from non-renewable constituents. An alternative polyurethane foam can be produced by replacing petroleum-based polyol with one that is derived from soybean oil. Polyurethane foams are often used as the core material for sandwich panels in structural applications and as energy absorption materials in car bumpers and other applications. In order to maintain structural integrity, these foams must display acceptable properties over a wide...

Fracture analysis of wood under variable environment

N. Angellier, R. Moutou Pitti & F. Dubois
The better knowledge of crack driving forces is very important in the assessment of the reliability of timber structures. This work is part of the CLIMBOIS project related to the effects of climatic and mechanical variations on the durability of timber structures. It deals with several fracture tests performed in climatic chamber on the cracking of specimens machined in Douglas and White Fir species. Opening mode crack growth is studied with adapted specimen’s geometry. Both...

Acoustical characterization and modelling of agricultural byproducts for building insulation

E. Gourdon, P. A. Chabriac, P. Glé, A. Fabbri & F. McGregor
In a general context of global warming, an increasing interest is observed on the use of biobased insulating materials. Indeed, this kind of materials ensures good thermal characteristics while drastically reducing fossil energy consumption and greenhouse gas emissions associated with their manufacture. In addition, thanks to their permeancy (ability to allow diffusion of water vapor within their porous network), these materials present an alternative option to isolate and rehabilitate buildings made with non-industrial materials (rammed...

3D X-ray tomography for the hygrothermal characterization of spruce wood

C. El Hachem, K. Abahri & R. Bennacer
The bio-based material considered in this work is spruce wood. Because of its complex morphology and high heterogeneity, this material still presents lacks of knowledge, concerning microscopic geometric changes, due to the hygrothermal solicitations. These changes lead usually to a considerable evolution of the resulting thermophysical properties of the material which constrains its use. The swelling and shrinkage phenomena, observed at the macroscopic scale, are the main witnesses reflecting such change caused by the hygric...

Bamboo panels to control moisture level of buildings

D. M. Nguyen, A. C. Grillet, J. Weiss, T. S. Phan Nguyen, M. H. Diep Thi & M. Woloszyn
The traditional use of bamboo throughout South East Asia is very diverse: fences, scaffolding, kitchen equipment, furniture, mats, blinds, toothpicks, paper pulp… Some applications use bamboo cane as such, however the current tendency is also towards an unstructured use of bamboo in the form of fibers or chips or even ashes. From strips, a wide variety of boards and plywood are made. Panels from bamboo fibers compressed in the presence of an organic resin are...

Heat transfer of dowelled and bolted steel-to-timber connections exposed to fire: experimentation and numerical modeling

A. Samaké, P. Audebert & M. Taazount
This exploration is dedicated of the experimental and numerical studies of heat transfer in timber-to-metal connections (bolts and dowels) in a fire exposure. The study was performed experimentally by testing specimens of connections in an oven with gas burner under the action of an ISO 834 fire temperature-time curve. Then, medialization of these specimens is made under the Msc_Marc software. The numerical model is based on finite element modeling. Finally a comparative study and discussions...

Experimental study of the hygrothermal behaviour of hemp shives-based precast blocks at material and wall scales

T. L. Vu, S. Spagnol & C. Magniont
This work aims to characterize the hygrothermal behavior of precast blocks made of hemp shiv aggregates and of a pozzolanic binder. The first part of the paper consists in the determination of basic hygrothermal properties of hemp concrete at material scale: thermal conductivity, thermal effusivity, vapor sorption isotherm, and water vapor permeability were assessed. The second part aims to develop a new tool allowing hygrothermal solicitation of a whole wall made of hemp concrete blocks...

Influence of liquid water on thermal and acoustical properties of hemp concretes

E. Gourlay, G. Pot, P. Glé, E. Gourdon & A. Feeser
Hemp concrete is a multifunctional ecological material used in buildings which is obtained by mixing together a binder and hemp particles (the non-fibrous fraction of the hemp stem called “shiv” or “hurd”). Due to its high porosity (ranging from 60 to 90% in volume), it presents an “atypical” mechanical behavior and its hygrothermal and acoustical properties are particularly interesting. This paper focuses on the influence of liquid water on thermal and acoustical properties of hemp...

Effect of water on the characteristics of polyethylene / flax fibers composites

L. Van Schoors, M. Gueguen-Minerbe, S. Moscardelli, H. Rabii & P. Davies
Flax reinforced polyethylene composites were subjected to sorption /desorption cycles, at 96% relative humidity and 30°C. Then, a multi scale characterization was realized. The mechanical properties of composites decrease during the sorption cycle, in particular the modulus which may be related to plasticizing phenomena, but recover their initial values after drying. No physico-chemical changes were observed during this ageing. Moreover, a microbiological survey revealed that the composites were sensitive to microbial development, especially when the...

Experimental study of the effect of adding fan palm fibers on concrete durability exposed to severe environments

M. Machaka & A. ElKordi
Adding Fiber to Concrete became a common practice to improve its durability, but for environmental purposes, it is preferable to use natural fibers instead of synthetic ones. In addition, using fibers prepared from tree waste that improves many concrete physical and mechanical properties is environmentally effective and costly preferable. Natural fibers extracted from Fan Palm trees that were cured chemically when used in concrete lead to improvements in concrete physical and mechanical properties. On the...

3D printing of fibre cement-based materials: fresh and rheological performances

M. Rubio, M. Sonebi & S. Amziane
The aim of this paper is to investigate the effect of different mix composition on fresh and rheological properties of a printable mortar. For the mix design, two binders such as fly ash (FA), and silica fume (SF) were used with cement and sand for a water/binder ratio of 0.50. Polypropylene fibres (PP), superplasticizer (SP), and viscosity modifying agents VMA (Diutan gun and nano-clay) were used in the investigation. The results show that adding 24%...

Investigation on the performance and durability of treated hemp concrete with water repellent

C. Sentenac, M. Sonebi & S. Amziane
Hemp concrete is an organic based building material. Hemp concrete principal weakness point is the mechanical performance such as the compressive 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, water repellent and two different binders. The mechanicals performance such as the compressive strength at 7, 14 and 28...

Biochar as a bond enhancement in fiber-reinforced mortar

H. W. Kua, S. Gupta & C. Tan
This study focuses on the evaluation of using biochar to enhance the strength performance of cement mortar reinforced with polypropylene (PP) fibers. Biochar was produced with mixed wood sawdust that was discarded from a local sawmill. It was then divided into two groups, with one group being subjected to dosage of carbon dioxide until it reached saturation. Results showed that when reinforcing PP fibers are coated with CO2-dosed biochar, the cement mortar experienced a 13%...

Assessing a method of bamboo treatment and its effects on the durability and mechanical performance

H. D. Tran, Q. B. Bui & A. C. Grillet
Bamboo is a natural material having a fast reproduction and excellent mechanical properties. However, when a natural material in general and bamboo in particular are expected to be a construction material, their durability is always questionable. Indeed, it is well known that these materials do not possess the same performance at the long-term, comparing to industrial materials. A sustainable solution for the bamboo treatment still needs to be investigated. The present study explores the oil-heated...

Mechanical enhancement of casted and compacted earth-based materials by sand, flax fiber and woven fabric of flax

F. Menasria, A. Perrot, D. Rangeard & A. Le Duigou
Earth-based materials are commonly reinforced with bio-based materials such as straw. In this study, we use high performance bio-based flax fibers and fabrics. The aim of this work is to find reinforcements that are able to improve the mechanical strengths and the ductility of an earthbased matrix. We also try to describe the reinforcement mechanisms are also described. In a first step, a kaolinite-based clay soil is mixed with sand to design earth-based mortars with...

Caractérisation expérimentale de la résistance au cisaillement de l’interface pâte de ciment-granulat

M. Jebli, F. Jamin, E. Garcia-Diaz & M.S. El Youssoufi
Il est généralement admis que la microstructure de la zone d'interface entre les granulats et la pâte de ciment dans un béton est caractérisée par une porosité supérieure à celle de la pâte de ciment. Les propriétés de cette zone de fragilité influencent fortement le comportement mécanique du béton à l’échelle macroscopique et, donc, à l’échelle de la structure. Dans ce travail, la résistance à la rupture en cisaillement de la liaison pâte de ciment-granulat...

Projet RECYMENT : Réactivité physico-chimique de graves recyclées utilisées en technique routière

P-Y. Mahieux, Ph. Turcry, H. Hamdoun, O. Amiri, V. Ferber & L. Chateau
La principale filière de valorisation des bétons de démolition consiste à les transformer en graves recyclées (GR) pour les travaux routiers en substitut des graves non traitées de carrière (GNT). Lauréat de l’appel à projets « Déchets du BTP 2013 », le projet Recyment avait entre autres pour objectif d’étudier la réactivité potentielle de graves recyclées d’une plateforme de recyclage rochelaise. Les GR présentent des performances au moins équivalentes à celles des graves de carrière....

Analysis of capillary bridges using imaging techniques and recent analytical model.

B. Mielniczuk, O. Millet & M. S. El Youssoufi
Les propriétés mécaniques des matériaux granulaires non saturés sont directement liées aux interactions capillaires résultant de la présence d’eau entre les grains. Dans ce l’article, le modèle analytique récent obtenu dans [GAG 14] est utilisé pour analyser les interactions capillaires à l’échelle du pont liquide entre deux grains sphériques. Les profils géométriques des ponts capillaires sont obtenus en résolvant l’équation de Young-Laplace considérée comme un problème inverse, la pression capillaire étant inconnue. La donnée de...

Optimisation d'un matériau ettringitique pour le stockage de chaleur

Khadim Ndiaye, Stéphane Ginestet, Martin Cyr & Gabriel Samson
Les matériaux de stockage sont utilisés dans le bâtiment pour éviter le décalage entre l’irradiation solaire et les besoins de chauffage. L’ettringite, hydrate principal des ciments sulfoalumineux (CSA), présente l’avantage d’avoir une grande densité de stockage à basse température. Un matériau de stockage à forte teneur en ettringite a été développé par hydratation de ciment sulfoalumineux dans un travail antérieur. Afin de prédire le comportement thermo-hydrique du matériau cimentaire en cycle stockage-déstockage, un modèle numérique...

Simplified 1D model of groundwater transient flow through a multilayered riverbank soil

Sambath Ky, Juan Martinez & Soksan Chhun
Le niveau de la nappe phréatique le long des berges d’une rivière varie en fonction de la fluctuation du niveau d’eau de la rivière. Par conséquent, la stabilité des berges est sensible au niveau variable des pressions interstitielles générées. C’est pourquoi, pour évaluer le risque d’effondrement des berges, l’étude de l’écoulement transitoire de l’eau dans la berge, généralement multicouche, est de première importance. Le modèle d’écoulement simplifié 1D proposé est basé sur, (i) l’hypothèse de...

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