Personne :
Cloutier, Alain

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Université Laval. Département des sciences du bois et de la forêt
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Voici les éléments 1 - 10 sur 69
  • Publication
    Characterization of juvenile wood to mature wood transition age in black spruce (Picea mariana (Mill.) B.S.P.) at different stand densities and sampling heights
    (International Academy of Wood Science, 2005-11-24) Cloutier, Alain; Alteyrac, Jérôme; Zhang, S. Y.
    The radial pattern of both maximum ring density and ring area of 36 black spruce trees were used to determine the transition age from juvenile wood to mature wood. The data were obtained by X-ray densitometry and both segmented linear and polynomial regressions were used to point out the age of the juvenile wood boundary. Three stand densities (1,790, 2,700 and 3,400 stems/ha) and three sampling heights (2.4, 5.1 and 7.8 m) were studied. Although maximum ring density and ring area presented similar radial patterns, they gave two significantly different results of transition ages. The maximum ring density over-estimated the transition age (17.6 years) in contrast to ring area (14 years). The results show that the transition from juvenile wood to mature wood occurred after 12 years at 7.8 m (versus 13.1 years at a height of 5.1 m, and 17.6 years at 2.4 m). Although transition age occurred later in the high stand density group (21 years), the difference was not significant between the three stand density groups. Nevertheless, transition age remains difficult to determine since no standard definition exists. The transition occurs over years, and most probably a transition wood exists between juvenile wood and mature wood. Estimation of the juvenile wood proportion in volume shows that it remains constant along the stem and it increases with stand density.
  • Publication
    Design of a low-density wood-cement particleboard for interior wall finish
    (Pergamon Press, 2011-10-13) Tittelein, Pierre; Bissonnette, Benoît; Cloutier, Alain
    Gypsum boards form a very large part of the building walls and ceilings finishing market. However, they have poor screw-withdrawal resistance, low hardness and are highly sensitive to moisture. The objective of this study was to determine whether it is possible to make wood–cement particleboards of the same density as gypsum boards while avoiding these drawbacks. Wood–cement particleboards were made by pouring the wood–cement paste in a mould. This was made possible by adding a viscosity modifying mixture to the mixing water and a set accelerating mixture to improve wood/cement compatibility. The mechanical properties and surface quality of the wood–cement particleboards were improved by using, on the board surfaces, paper sheets that were the same as those used on gypsum boards. The average specific gravity of the wood–cement particleboards was the same as gypsum boards, at 0.7. The average bending modulus of rupture obtained for the wood–cement particleboards was 10 MPa in the finishing paper principal direction and 5 MPa in the other direction compared to 5.5 MPa and 1.6 MPa respectively for gypsum boards. The average screw-withdrawal resistance of wood–cement particleboards was 570 N, that is, 1.7 times higher than for gypsum boards.
  • Publication
    Wood degradation after windthrow in a northern environment
    (Forest Products Society, 2010-01-31) Ruel, Jean-Claude; Cloutier, Alain; Espinoza-Herrera, Raul; Achim, Alexis; Brossier, Benoît
    Severe windthrows often require salvage operations that can lead to increased costs. Given these extra costs, it is of paramount importance to make sure that wood degradation does not become so advanced that significant value loss is incurred. The rate at which wood deteriorates is a function of many factors, including species and climate. The study was conducted in a northern area affected by two partial windthrows. Logs from the damaged area were collected for two species, balsam fir (Abies balsamea) and black spruce (Picea mariana). Logs were classified into one of three degradation classes based on visual assessments. A sample of logs from standing trees was also collected. In total, 167 logs were sampled. Each log was sawn and one piece of lumber was selected from each to determine the bending strength and stiffness and the visual grade. The time since tree death, as determined from dendrochronology, ranged from 1 to 31 years. The visual grade of the lumber was not affected after 1 year but severe downgrades were observed after 4 years. Moisture content decreased rapidly for both species during the first year and continued to decrease until 4 years after mortality. No clear decrease in bending stiffness was identified even though such a tendency was noticed for older black spruce windthrows. Bending strength became variable after 4 years for balsam fir and was reduced after 4 years for black spruce. Windthrows older than 7 years will produce low visual grade timber of reduced bending strength and possibly of lower bending stiffness.
  • Publication
    Accès libre
    Fuel properties of sugar maple and yellow birch wood in relation with tree vigor
    (North Carolina State University, 2016-05-01) Cloutier, Alain; Stevanovic-Janezic, Tatjana; Achim, Alexis; Nguyen, Quy Nam
    The fuel properties of wood obtained from sugar maple (SM) and yellow birch (YB) of temperate hardwood stands located in the Province of Québec, Canada were studied to see how tree vigor affects the chemical composition and calorific value of the wood. This study focused on the physical and chemical properties of wood with the aim of using the material for the production of solid biofuels. Specific items measured included the wood’s calorific values, and the levels of extractives, ash, and lignin. Changes in chemical composition were found among tree vigor classes. The low vigor trees had higher extractives, ash, and lignin contents than the vigorous trees. Total extractives ranged between 4.88 and 7.32% in SM, and between 3.35 and 5.12% in YB. Klason lignin ranged between 21.46 and 23.53% in SM, and between 18.60 and 21.51% in YB. Ash content ranged between 0.38 and 0.97% in SM, and between 0.26 and 0.47% in YB. The combined effects of higher lignin content that could contribute to a better self-bonding of particles and of higher extractives content that could facilitate the pelletization process makes the low vigor trees more suitable for conversion into solid biofuels. The higher amounts of extractives and lignin present in the low vigor sugar maple and yellow birch trees could also have a positive role in maintaining the high calorific values of this wood despite higher ash content.
  • Publication
    Accès libre
    Determinacion de un elemento de volumen representativo de probetas de tablero tensado
    (Universidad del Bío-Bío, 2012-09-14) Sepúlveda, Daniela; Cloutier, Alain; Gacitúa Escobar, William; Bustos, Cecilia; Dechent, Peter
    El objetivo de este estudio fue definir un elemento de volumen representativo para caracterizar las propiedades mecánicas de probetas de tableros tensados de Pinus radiata D. Don y de Eucalyptus nitens. La determinación del elemento de volumen representativo permitió identificar la sección más pequeña de las probetas que presenta las particularidades de este material compuesto y por consiguiente, representa a la probeta en su conjunto. Para esto, las propiedades nanomecánicas de las paredes celulares y lamela media fueron determinadas por nanoindentaciones. Este estudio se desarrolló en dos etapas. En la primera etapa, el anillo de crecimiento representativo de las piezas de madera bajo compresión perpendicular a la fibra, fue determinado. En la segunda etapa, el tablón representativo de la probeta de tablero tensado sometido a compresión a largo plazo, fue determinado. Los resultados de la primera etapa, mostraron que no existe una tendencia específica de las propiedades nanomecánicas a través de los anillos de crecimiento en la sección transversal de las piezas de Pinus radiata y Eucalyptus nitens bajo compresión perpendicular a la fibra. En la segunda etapa, se estableció que los esfuerzos de compresión a largo plazo en la probeta de tablero tensado principalmente afectaron las propiedades nanomecánicas de la estructura celular de los tablones exterior y central de la probeta. Lo anterior permitió establecer que el elemento de volumen representativo de una probeta de tablero tensado se localizó en la madera temprana del anillo de crecimiento más alejado a la médula en la sección transversal del tablón central.
  • Publication
    Accès libre
    Steatite powder additives in wood-cement drywall particleboards
    (Molecular Diversity Preservation International, 2020-10-29) Bissonnette, Benoît; Dagenais, Christian; Cloutier, Alain; Vu, Viet-Anh; Blanchet, Pierre
    The 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.
  • Publication
    Modeling vacuum-contact drying of wood : the water potential approach
    (2007-05-10) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    A two-dimensional mathematical model for vacuum-contact drying of wood is presented. The moisture and heat equations are based on the water potential concept whereas the pressure equation is formulated considering unsteady state conservation equation of dry air. Most of the model parameters were determined during independent experiments. The set of equations is then solved in a coupled form using the finite element method. The validation of the model is performed using experimental results obtained during vacuum-contact drying of sugar maple sapwood. The experimental and calculated data are in good agreement. Nevertheless, some discrepancies are observed which can be attributed to the boundary conditions used and to the fact that heat transfer by convection was neglected.
  • Publication
    Accès libre
    Phenotypic correlations among growth and selected wood properties in white spruce (Picea glauca (Moench) Voss)
    (MDPI, 2019-07-16) Mvolo, Cyriac Serge; Defo, Maurice.; Cloutier, Alain; Koubaa, Ahmed; Ngueho Yemele, Martin Claude; Beaulieu, Jean
    We examined phenotypic relationships among radial growth-related, physical (i.e., related to wood density), and anatomical (i.e., related to tracheid dimensions) wood properties in white spruce (Picea glauca (Moench) Voss), in order to determine the strength and significance of their correlations. Additionally, principal component analysis (PCA) was used to establish if all of the properties must be measured and to determine the key properties that can be used as proxies for the other variables. Radial growth-related and physical properties were measured with an X-ray densitometer, while anatomical properties were measured with a Fiber Quality Analyzer. Fifteen wood properties (tracheid length (TL) and diameter (TD), earlywood tracheid length (ETL) and diameter (ETD), latewood tracheid length (LTL) and diameter (LTD), ring width (RW), ring area (RA), earlywood width (EWW), latewood width (LWW), latewood proportion (LWP), ring density (RD), intra-ring density variation, earlywood density (EWD), and latewood density (LWD)) were assessed. Relationships were evaluated at intra-ring and inter-ring levels in the juvenile wood (JW) and mature wood (MW) zones. Except for a few cases when mature tracheid diameter (TD) was involved, all intra-ring anatomical properties were highly and significantly correlated. Radial growth properties were correlated, with stronger relationships in MW compared to JW. Physical properties were often positively and significantly correlated in both JW and MW. A higher earlywood density coupled with a lower latewood density favored wood uniformity, i.e., the homogeneity of ring density within a growth ring. Managing plantations to suppress trees growth during JW formation, and enhancing radial growth when MW formation starts will favor overall wood quality. In order, RW-EWW-RA, TL-ETL-LTL, and RD-EWD-LWP are the three clusters that appeared in the three wood zones, the whole pith-to-bark radial section, the juvenile wood zone, and the mature wood zone
  • Publication
    Development of a new engineered wood product for structural applications made from trembling aspen and paper birch
    (Forest Products Research Society, 2009-07-31) Beck, Katherina; Cloutier, Alain; Salenikovich, Alexander; Beauregard L., Robert
    This study compared the bending performance of small (30 mm [1.2 in.] deep) laminated beams made from aspen oriented strand lumber (OSL), birch OSL, and commercial web-stock oriented strandboard (OSB) panels. Aspen OSL beams had an average modulus of elasticity (MOE) of 9.89 GPa (1.43 × 10^sup 6^ psi) and an average modulus of rupture (MOR) of 52.0 MPa (7.54 × 10^sup 3^ psi). The average MOE for birch OSL was 10.6 GPa (1.54 × 10^sup 6^ psi), and the average MOR was 58.4 MPa (8.47 × 10^sup 3^ psi). OSB laminated beams reached less than half of these values (5.17 GPa [0.75 × 10^sup 6^ psi] and 26.4 MPa [3.83 × 10^sup 3^ psi], respectively). Large (120 mm [4.72 in.] deep) laminated OSB beams were also tested to track the depth effect. The average MOR of aspen and birch OSL, adjusted to 120 mm depth, was estimated to be 46.7 MPa (6.77 × 10^sup 3^ psi) and 52.6 MPa (7.63 × 10^sup 3^ psi), respectively. Comparisons with laminated strand lumber products currently on the Canadian market showed the mechanical properties of this new product to be competitive
  • Publication
    Prediction of tracheid length and diameter in white spruce (Picea glauca)
    (Rijksherbarium/Hortus botanicus, 2015-05-20) Mvolo, Cyriac Serge; Defo, Maurice.; Cloutier, Alain; Koubaa, Ahmed; Ngueho Yemele, Martin Claude; Beaulieu, Jean
    The establishment of patterns of radial and longitudinal variations and the development of models to predict the wood anatomical properties, especially from juvenile wood, are of interest for both wood industry and researchers. Linear regressions were used to predict whole-tree, breast height and mature tracheid length and diameter in white spruce (Picea glauca (Moench) Voss) and the WBE model was used to predict the variation of tracheid diameter. Tracheid length and diameter increased from pith to bark. Tracheid length decreased, while tracheid diameter increased from apex to lower heights. Cambial age was the most important predictor of tracheid length. The final tracheid length models with either a log transformation or a third-order polynomial of cambial age explained 82% of the variation in the whole-tree tracheid length. At breast height, 83% of the variation in the whole tracheid length was explained using the juvenile value at a cambial age of 3 years. Up to 87% of the variation was explained by the model, including the average value of juvenile wood. However, mature wood tracheid length at breast height could not be predicted from juvenile wood. Distance from the apex predicted the tracheid widening in outer rings but failed to predict tracheid expansion of samples collected at fixed cambial ages. The WBE explained 86% of conduit widening in the outer rings. The sampling strategy, i.e. collecting samples longitudinally at a fixed cambial age vs. at a fixed calendar year is important in predicting tracheid diameter.