Personne : Dagenais, Christian
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Université Laval. Département des sciences du bois et de la forêt
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- PublicationRestreintGlued-laminated timber from northern hardwoods : effect of finger-joint profile on lamellae tensile strength(Elsevier Ltd., 2020-11-24) Morin-Bernard, Alexandre; Blanchet, Pierre; Dagenais, Christian; Achim, AlexisBecause of their availability, mechanical properties and distinctive appearance, there is a growing interest for the use of hardwood species in structural products such as glued-laminated timber. Previous work on bonding and structural grading of northern hardwoods has shown that white ash (Fraxinus americana L.), yellow birch (Betula alleghaniensis Britt.) and white oak (Quercus alba L.) are promising species for the manufacture of Canadian hardwood glulam. The objective of this study was to investigate the impact of the finger joint profile on the tensile strength of jointed hardwood lamellae. Tensile tests conducted on finger-jointed lamellae confirmed the possibility to achieve characteristic tensile strengths up to 36.4 MPa for white ash, 33.6 MPa for yellow birch and 35.8 MPa for white oak. One white ash and two yellow birch full-size beams were also manufactured using the most efficient finger joint profile and submitted to bending tests, achieving strengths of 47.0 and 41.6 MPa, respectively. The investigated species gave promising results suggesting they could be suitable for the manufacture of glued-laminated timber, although further research is required on hardwood finger-jointing to optimize the machining and gluing parameters and increase the joint efficiency.
- PublicationAccès libreAboutage de l'érable à sucre pour la fabrication de produits de bois d'ingénierie structuraux(2007) Dagenais, Christian; Salenikovich, AlexanderLe bois abouté est souvent utilisé dans la fabrication de produits de bois d’ingénierie structuraux tels que le lamellé-collé et la poutrelle en I. Au Québec, les fabricants de produits de bois d’ingénierie utilisent principalement du bois du groupe Épinette-pin-sapin (EPS) qui comporte des essences de résineux acceptées dans les normes canadiennes. Étant un bois de feuillus, l’érable à sucre n’est pas une essence prescrite dans les normes de fabrication par contre, en théorie, ce bois peut offrir une alternative intéressante aux bois résineux compte tenu de sa résistance mécanique supérieure. Une revue de la littérature démontre qu’il existe plusieurs recherches sur l’aboutage par entures multiples, mais que celles portant sur l’aboutage de bois de feuillus sont plutôt rares. Plusieurs paramètres d’usinage doivent être contrôlés afin de fournir de belles surfaces de collage et d’optimiser le procédé d’aboutage. Ce projet vise à définir un intervalle de paramètres d’usinage pour l’aboutage structural par entures multiples de l’érable à sucre afin de développer les meilleures résistances mécaniques que ce bois peut potentiellement offrir. Plus spécifiquement, ce projet étudie la résistance en traction parallèle au fil en variant la vitesse de coupe ainsi que l’avance par couteau (chip-load). Des deux paramètres étudiés, la vitesse de coupe semble être le paramètre ayant le plus d’effet sur la résistance en traction parallèle au fil de l’érable à sucre. Les meilleures résistances furent atteintes avec une vitesse de coupe de 2726 m/min et une avance par couteau de 0,60 mm. La vitesse de coupe de 2726 m/min semble être la meilleure afin d’atteindre les meilleures résistances en traction parallèle au fil, et ce, peu importe l’avance par couteau. Finalement, les résultats obtenus nous permet de croire que l’érable à sucre abouté possède un bon potentiel pour des applications structurales dont la fabrication de produits de bois d’ingénierie structuraux.
- PublicationAccès libreFire performance of intumescent waterborne coatings with encapsulated APP for wood constructions(MDPI, 2021-10-20) Dagenais, Christian; Hoang, Doan-Trang; Hussain, Atif; Landry, Véronic; Blanchet, PierreIn this work, intumescent coatings were prepared for protection of wood from fire. The fire-retardant chemical ammonium polyphosphate (APP) is known to have poor resistance to water and high humidity as it is hygroscopic in nature. To improve the water resistance, durability and fire resistance of the intumescent coating, APP was modified using a hybrid organic-inorganic polysiloxane encapsulation shell prepared by the sol–gel method. The physical and chemical properties of the intumescent mix containing microencapsulated ammonium polyphosphate (EAPP) particles were characterized by X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), water absorption, dynamic vapor sorption (DVS) and thermogravimetric analysis (TGA). The EAPP mix showed 50% reduction in water absorption, 75% reduction in water vapor sorption and increased thermal stability when compared to the APP mix. The intumescent coatings were applied on wood samples, and their fire performance was evaluated using a cone calorimeter test. The intumescent coatings containing EAPP mix showed better fire retarding properties with longer time to ignition, lower heat release rate and shorter heat release peak when compared to the coating without EAPP mix. The prepared intumescent coating shows higher resistance to water and moisture, and it has great potential to be used in bio-based construction industry for enhancing the fire resistance of wood.
- PublicationAccès libreFire safety in tall timber building : a BIM-based automated code-checking approach(Stamats Communications, 2020-07-08) Kincelova, Kristina; Dagenais, Christian; Boton, Conrad; Blanchet, PierreFire safety regulations impose very strict requirements on building design, especially for buildings built with combustible materials. It is believed that it is possible to improve the management of these regulations with a better integration of fire protection aspects in the building information modeling (BIM) approach. A new BIM-based domain is emerging, the automated code checking, with its growing number of dedicated approaches. However, only very few of these works have been dedicated to managing the compliance to fire safety regulations in timber buildings. In this paper, the applicability to fire safety in the Canadian context is studied by constituting and executing a complete method from the regulations text through code-checking construction to result analysis. A design science approach is used to propose a code-checking method with a detailed analysis of the National Building Code of Canada (NBCC) in order to obtain the required information. The method starts by retrieving information from the regulation text, leading to a compliance check of an architectural building model. Then, the method is tested on a set of fire safety regulations and validated on a building model from a real project. The selected fire safety rules set a solid basis for further development of checking rules for the field of fire safety. This study shows that the main challenges for rule checking are the modeling standards and the elements’ required levels of detail. The implementation of the method was successful for geometrical as well as non-geometrical requirements, although further work is needed for more advanced geometrical studies, such as sprinkler or fire dampers positioning.
- PublicationAccès libreFire hazard of compressed straw as an insulation material for wooden structures(Heyden, 2020-06-07) Dagenais, Christian; Blondin, Frédéric; Blanchet, Pierre; Triantafyllidis, Zafiris; Bisby, LukeThe construction sector continues to adapt to the challenges posed by climate change. Architects and engineers aim to build sustainable, energy, resource, and cost‐efficient structures by increasingly using bio‐based building materials. However, fire safety has always been a significant concern for timber building construction internationally. The objective of the study presented in this article is to document fire hazards of compressed straw when used as thermal and acoustic insulation within wood‐framed building assemblies. Three densities of compressed straw (75, 125, and 175 kg/m3) were selected and their combustion and thermal responses were evaluated at various scales, in attempt to define the optimal density considering various factors. The performance of the straw was also compared with commercially available insulation materials and then tested under exposure to severe heating in medium‐scale wood‐framed assemblies to evaluate the impacts of the straw as compared with a noncombustible insulation. The compressed straw with a density of 75 kg/m3 was found to have the best behavior with respect to both reactions to fire and insulation properties. The results suggest that compressed may have similar or better behavior under the heating conditions investigated when compared to a commercially available combustible insulation material. The use of this material as a primary insulation in a buildings is considered manageable by thoughtful design, construction, and building use without unduly increasing risks associated with fire.
- PublicationRestreintUse of northern hardwoods in glued-laminated timber : a study of bondline shear strength and resistance to moisture(Springer, 2020-07-25) Morin-Bernard, Alexandre; Dagenais, Christian; Achim, Alexis; Blanchet, PierreThe growing demand for engineered wood products in the construction sector has resulted in the diversification of the product offer. Used marginally in structural products in North America, northern hardwoods are now attracting a growing interest from industry and policy makers because of their outstanding strength as well as their high availability and distinctive appearance. Currently, there is no standard in Canada governing the use of hardwoods in the manufacturing of glued-laminated timber. As part of a larger project aiming to assemble the basic knowledge that would lead to such standard, the specific objective of this study was to assess the shear strength in dry and wet conditions of assemblies made from different hardwood species and structural adhesives. Results suggest that a mean shear strength as high as 20.5 MPa for white oak, 18.8 MPa for white ash and respectively 18.2 MPa and 17.4 MPa for yellow birch and paper birch can be obtained in dry conditions. The choice of adhesive did not affect the dry shear strength of these specimens, but differences were observed in wet conditions. Specimens bonded with melamine-formaldehyde adhesive had generally the highest wet shear strength and wood failure values. These results also highlight the important influence of wood density on the percentage of failure that occurs in wood and, to a lesser extent, on shear strength. Further investigations on finger joint strength and full-size bending tests will allow confirming the potential for the investigated species to be used in glued-laminated timber.
- PublicationAccès libreHeat transfer behavior of green roof systems under fire condition : a numerical study(Stamats Communications, 2019-09-19) Gerzhova, Nataliia; Ménard, Sylvain; Dagenais, Christian; Côté, Jean; Blanchet, PierreCurrently, green roof fire risks are not clearly defined. This is because the problem is still not well understood, which raises concerns. The possibility of plants catching fire, especially during drought periods, is one of the reasons for necessary protection measures. The potential fire hazard for roof decks covered with vegetation has not yet been fully explored. The present study analyzes the performance of green roofs in extreme heat conditions by simulating a heat transfer process through the assembly. The main objective of this study was to determine the conditions and time required for the roof deck to reach a critical temperature. The effects of growing medium layer thickness (between 3 and 10 cm), porosity (0.5 to 0.7), and heating intensity (50, 100, 150, and 200 kW/m2) were examined. It was found that a green roof can protect a wooden roof deck from igniting with only 3 cm of soil coverage when exposed to severe heat fluxes for at least 25 minutes. The dependency of failure time on substrate thickness decreases with increasing heating load. It was also found that substrate porosity has a low impact on time to failure, and only at high heating loads.
- PublicationAccès librePreparation and characterisation of flame retardant encapsulated with functionalised silica-based shell(Taylor & Francis, 2018-09-07) Dagenais, Christian; Schorr, Diane; Hoang, Doan-Trang; Vanslambrouck, Stéphanie; Landry, Véronic; Blanchet, PierreIntumescent fire retardant (IFR) coatings are nowadays considered as the most effective flame retardant (FR) treatment. Nevertheless, the principal compound in an IFR system, ammonium polyphosphate (APP), is highly sensitive to moisture and IFR coating effectiveness decreases quickly. The main objective of this study is to encapsulate APP in a hybrid silica-based membrane by sol-gel process using alkoxysilane tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) precursor. The morphology and structure of APP and microencapsulated ammonium polyphosphate (MAPP) were assessed by scanning electron miscroscopy and Fourier transform infrared spectroscopy (FTIR). X-ray photoelectron spectroscopy (XPS) results revealed that APP was well encapsulated inside the polysiloxane shells. The thermal degradation of APP and MAPP was evaluated by thermogravimetric analysis. At 800°C, the MAPP had higher char residue (70.49 wt%) than APP (3.06 wt%). The hydrophobicity of MAPP increased significantly with the water contact angles up to 98°, in comparison to 20° for APP.
- PublicationAccès libreFlammability characteristics of green roofs(Stamats Communications, 2020-07-09) Gerzhova, Nataliia; Ménard, Sylvain; Dagenais, Christian; Côté, Jean; Blanchet, PierreAssessing the fire risk of vegetated roofs includes the determination of their possible contribution to fire. Green roof components such as plants and growing media are organic materials and present a fuel that can catch and support the spread of fire. The flammability characteristics of these components were analyzed and compared to a typical roof covering. Growing media with 15% of organic matter were tested using cone calorimeter apparatus. The fuel load and heat release rate of the growing media were measured in both moist (30%) and dry conditions. It was observed that growing media in a moist condition do not present a fire risk, reaching a maximum heat release rate of 33 kW/m2. For dry substrates, a peak heat release rate of 95 kW/m2 was recorded in the first minute, which then rapidly decreased to 29 kW/m2 in the second minute. Compared to a typical bitumen roof membrane, the green roof showed a better fire performance. The literature data report more severe results for plant behavior, reaching peak heat release rates (HRRs) of 397 kW/m2 for dried and 176 kW/m2 for a green material. However, a rapid decrease in HRR to much lower values occurs in less than 2 min. The results also show that extensive and intensive types of green roofs present 22% and 95% of the additional fire load density when installed on a modified bitumen membrane, 19.7 and 85.8 MJ/m2, respectively.
- PublicationAccès libreSteatite powder additives in wood-cement drywall particleboards(Molecular Diversity Preservation International, 2020-10-29) Bissonnette, Benoît; Dagenais, Christian; Cloutier, Alain; Vu, Viet-Anh; Blanchet, PierreThe objective of this study was to develop a new drywall wood-based particleboard as an alternative to gypsum board. Various development iterations have led to the use of wood particles, steatite powder and Portland cement. The resulting outcome shows that screw withdrawal resistance was improved by 37% and bending properties by 69% compared to gypsum board of a similar density (0.68–0.70). The raw surface of the boards is of good quality and comparable to the paper-faced surface of gypsum board. Furthermore, the reaction to fire was evaluated through bench-scale test with a cone calorimeter. The investigated particleboard did not reveal visual signs of combustion after 20 min when exposed to a radiant heat of 50 kW/m2, while burning of the overlay paper of gypsum board occurred at about 57 s, suggesting that wood-cement-steatite powder particleboard could be classified as a quasi non-combustible material.