Category Archives: Scientifiques

The Multifactorial Aspect of Wood Weathering: A Review Based on a Holistic Approach of Wood Degradation Protected by Clear Coating

Abstract

Wood is an abundant and renewable natural resource. Its use is promoted as a way to reduce the carbon footprint in building construction. Wood structures are degraded by their environment due to weathering. This review is a meta-analysis of the main factors of degradation that belong to this pehnomenon. The impact of irradiation, the role of water, oxygen, temperature, and colonization by fungi are explained. To protect against these factors. the use of coatings is the most common solution. Since currently the trend is to maintain the grain and the natural color of the wood, the use of transparent coatings is fasvored. This review présents the main technologies used in clear wood coatings. THe durability of this protection against weathering is approached. The whole of knowledge gathered has made it possible to begin a discussion on the multifactorial aspect of wood weathering. Schèmes were created to synthesize the synergistic and antagonistic effects between the degradation factors.

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LEED v4: Where AreWe Now? Critical Assessment through the LCA of an Office Building Using a Low Impact Energy Consumption Mix

Summary

Various green building rating systems (GBRSs) have been proposed to reduce the environmental impact of buildings. However, these GBRSs, such as Leadership in Energy and Environmental Design (LEED) v4, are primarily oriented toward a building’s use stage energy consumption. Their application in contexts involving a high share of renewable energy, and hence a low-impact electricity mix, can result in undesirable side effects. This paper aims to investigate such effects, based on an existing office building in Quebec (Canada), where more than 95% of the electricity consumption mix is renewable. This paper compares the material impacts from a low-energy context building to material considerations in LEED v4. In addition to their contributions to the building impacts, material impacts are also defined by their potential to change impacts with different material configurations. Life cycle assessment (LCA) impacts were evaluated using Simapro 8.2, the ecoinvent 3.1 database, and the IMPACT 2002+ method. The building LCA results indicated higher environmental impact contributions from materials (>50%) compared to those from energy consumption. This is in contrast with the LEED v4 rating system, as it did not seem to be as effective in capturing such effects. The conclusions drawn from this work will help stakeholders from the buildings sector to have a better understanding of building environmental profiles, and the limitations of LEED v4 in contexts involving a low-impact energy mix. In addition, this critical assessment can be used to further improve the LEED certification system.

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Synthesis and incorporation of poly(methyl methacrylate) microspheres with UV stabilizers in wood clear coating binder

Abstract

The durability of clear coatings is an important problem in the coatings industry. This problem can be partly solved with the addition of UV absorbers (UVAs) in the coating formulation. UVAs can absorb part of the UV radiation and convert it into harmless heat. Organic UVAs are prone to photodegradation and can migrate in the binder of a coating formulation. In this study, commercial UVAs have been encapsulated in poly(methyl methacrylate) microspheres using the internal phase separation method. Microspheres have been incorporated into a clear acrylic binder. The acrylic was then applied on wood panels and was placed into an artificial UV chamber. Efficiency of coatings after aging as well as chemical and physical properties were monitored using a colorimeter, FTIR spectroscopy and transmission electron microscopy. This study presents a comparison between the efficiency of free and encapsulated Tinuvin 1130 and 292 commercial absorbers. Results have shown that the coating efficiency is slightly improved when using the encapsulated products.

Determination of In Situ Esterification Parameters of Citric Acid-Glycerol Based Polymers for Wood Impregnation

Abstract

The development of wood treatments is of increasing industrial importance. A novel technique for improving the properties of lodgepole pine and white pine through modification of the microstructure is described. The present investigation is devoted to the synthesis and determination of in situ parameters of citric acid and glycerol based polymers for wood impregnation. This solvent free approach is environmentally friendly and achieved through an esterification condensation reaction under acidic conditions. Crude glycerol and citric acid reactants were cross-linked via a curing process at 160 °C creating a polymer with only water as the byproduct. The ester bonds and crosslinking levels were controlled using different catalysts and citric acid contents and related to the reaction time and temperature. The nature of bonding within the polymers and at the wood cell walls was determined by FT-IR analysis. The thermal properties such as glass transition temperature (Tg) were studied using TGA/DSC and the effect of citric acid content and catalyst type determined. Dimensional stability of impregnated wood samples improved above 50% for each sample with HCl and p-TSA catalysts compared to control samples. FTIR spectra were studied to show the presence of the ester linkages of the polymer in situ at the wood cell walls. Bonding between the polymer and wood macromolecules were observed by scanning electron microscopy and interpreted as evidence of chemical bonds at the wood cells. When prepared using a catalyst, the polymer was intimately incorporated into wood structure significantly improving the substrate dimensional stability. Enhanced stability makes this approach of particular interest for exterior wood products especially as a green renewable option for the wood industry.

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Effects of interior wood finishes on the lighting ambiance and materiality of architectural spaces

Wood is a material often used by architects to enhance the overall ambience of a space, but few researches have been reported to discuss its actual impact on visual impression and luminous effects. This research studies the influence of wood materiality in relation to creating specific lighting ambiances in architecture. In particular, it focuses on the impact of decorative wood indoor panels on the creation of daylighting diversity in interior space and the potential to improve daylighting quality and energy efficiency. The research uses scaled models for their accuracy in rendering complex daylighting ambiances. The photo-luminance meter enables the comparison between different settings of interior spaces created by a selection of wood type materiality: ratio (percentage), colour (Oak, Cape Cod Grey and Dark Walnut coatings) and gloss concerning illuminance patterns obtained from Ecotect software. The CIE L*a*b* colour space is used to classify luminous ambiances. Results indicate that bright colour Oak favours a deeper daylighting penetration and increases the colour temperature of the space by about 300% when applied on the floor. Cape Cod Grey coating provided a neutral colour balance even under sunlighting. High gloss Dark Walnut located on the ceiling produces the highest luminance values, enlarging the window-lighting pattern. The research underlines the role of wood materiality in achieving luminous diversity and creating visually comfortable interior ambiances.

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Impact of a reinforcement treatment with acrylate impregnation on the mechanical behavior of black spruce as connector member

Abstract

As a previous study has shown, it is possible to increase by 50% the dowel bearing strength of black spruce with an acrylate formulation applied by impregnation. Three diameters of bolts and two orientations of loading were included in this study. The effect of treatment on the dowel-bearing strength appeared to increase while the diameter of bolt decreased. The orientation of loading was significant as the treatment had a major impact in the parallel to grain direction and no impact in the perpendicular direction. With the digital image correlation analysis, an expanded strain field perpendicular to the load direction was observed. The superior embedding capacity would help to reduce the dimensions of the timbers as well as the number of connections required in the building design. With an increase of ductility, wood connections show a safer yielding behavior.

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Experiencing Wooden Ambiences with Nordic Light: Scale Model Comparative Studies Under Real Skies

Abstract

This study explored the potential of natural light to enhance wooden interior environments. Under Nordic light, natural materials such as wood finishes present an opportunity to create warm, bright, and pleasant atmospheres, enhancing psychological well-being and comfort. The objectives of this project were twofold: first, to study the diversity of northern sky conditions in terms of cloud cover and thickness, and, second, to evaluate the impacts of the diversity of natural light on five wooden scale models. The methodology involved weather data collection that took place during the spring equinox in Quebec City. In order to create a cloudiness scale, sky condition data and photometric measurements were collected. A photographic survey occurred in five scale models made with interior wooden finishes of varying color combinations, documenting the impact of sky diversity on brightness, hue, and contrast. Simultaneous scale model studies under a real sky allowed direct comparison under the same lighting conditions. There was a remarkable diversity of visual ambiences for a southeast-oriented space depending on the position of the sun and sky conditions. Gray-dyed wooden finishes created dull and unchanging atmospheres, while yellow oaked surfaces allowed various dynamic ambiences.