Fig 1 - uploaded by Thierry Koumbi Mounanga
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Example of a wood block sample with glue-line sawn longitudinally (lengthwise) from boards radially generated from logs that were cut longitudinally at the saw mill
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Borate distribution and content in re-wetted brush-treated Eastern black spruce (Picea mariana var. mariana) blocks were investigated by near-infrared spectroscopy (NIRS). Samples were brush-treated with 40 % glycerol-based DOT (Na2B8O13 4H2O) and then conditioned for different durations (5, 9, 20, and 30 days) at high relative humidity (approachin...
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... ON, Canada). They were kept in conditioning chamber at 15 °C and relative humidity (RH) [95 % until surface-planed and cut into forty wood blocks with 3.5 9 6 9 9 cm 3 dimensions in tangential, longitudinal and radial directions, respectively. These samples were used to study the borate distribution, borate content and effect of a glue-line (Fig. 1). Twenty of the blocks were bonded to 1 9 3.5 9 6 cm 3 (radial/tangential/longitudinal) wafers with liquid phenol- formaldehyde (PF) resin supplied by Momentive Specialty Chemicals Canada, Inc. (Edmonton, AB, Canada) to study the glue-line effect. Manufacturer specifications for PF physical and chemical properties are described by ...
Citations
... These observations indicate that preservative penetration in CLT can be predicted based on L L and L T values. Also, the results suggest that the Cu diffusion in CLT panel's thickness direction across adjacent layers is prohibited (because of the glue layer), and this diffusion can be disregarded in the preservative treatment of lumber-based wood composites [37]. ...
Cross-laminated timber (CLT), a prefabricated multilayer engineered wood product, is a promising construction material for mid-and-high rise buildings due to its good mechanical properties, renewability, and low-carbon footprint. However, the vulnerability of CLT to biodeterioration limits its broad applications. Preservative treatment is an effective method of increasing the service life of structural wood products, while the treatment of CLT has not been widely studied. Herein, we fabricated 3- and 5-ply CLT panels and treated them with Cu-based preservatives. The effects of panel layup (lengthwise and crosswise) and thickness (3-and 5-layer) on the impregnation quality (i.e., Cu penetration and retention) are investigated using a color-based indicator approach and X-ray fluorescence spectroscopy . Generally, the Cu penetration ratio was mostly above 90%, especially for the top layers (1st layer in 3-ply and 1st and 2nd layers in 5-ply) of the treated CLT panels. Similarly, higher Cu retention values were observed in the 1st layer of the 3- and 5-layer CLT panels. Further, there was a similarity in the Cu penetration of the 2nd layer in 3- and 5-ply CLT, indicating the preservative diffusion across adjacent layers is negligible in the preservative treatment of lumber-based wood composites. Overall, copper-azole type C (CA-C) exhibited better treatability than micronized copper azole (MCA) for CLT panels, resulting in higher Cu penetration and retention across the panels. Also, we found the lengthwise orientation preferable in fabricating preservative-treated CLT, this is due to the complete panel protection of the 1st and 2nd layers at all panel locations. Thus, our results show the feasibility of successfully treating CLT, especially when CA-C preservative and lengthwise orientation are utilized in fabricating the panels.
... La medición de los niveles de retención de sales de boro en la madera facilita establecer la idoneidad de un determinado tratamiento de impregnación y la aptitud que tiene una especie para preservarse del fuego (Koumbi-Mounanga et al., 2015, Pereira et al., 2017. Existe evidencia empírica de que, si una probeta de madera de pequeñas dimensiones es impregnada con sales de boro y expuesta al fuego, el tiempo de ignición y la pérdida de masa disminuyen (Sogutlu et al., 2011;Uner et al., 2016;Jin & Chung, 2018). ...
Resumen La madera es un material combustible, motivo por el cual es importante investigar técnicas para aumentar su resistencia al fuego. La retención de sales de boro en la madera mide la idoneidad del tratamiento de impregnación y la aptitud que tiene una especie para su preservación y reacción al fuego. Los objetivos de la investigación fueron, por una parte, determinar su densidad aparente y su capacidad de retención de sales de boro y, por otra, medir el tiempo de ignición y la pérdida de masa en pruebas de reacción al fuego. La investigación comprobó la capacidad de retención de sales de boro de Spathodea campanulata (Tulipán africano), Fraxinus americana (Fresno blanco) y Albizia plurijuga (Tepehuaje). Para cada especie, se impregnaron cuarenta probetas de pequeñas dimensiones con el método de baño caliente-frío con una solución de ácido bórico y borato de sodio con concentraciones de uno, dos y tres por ciento. Se determinaron la densidad y el contenido de humedad de la madera. Se realizaron pruebas de reacción al fuego con duración de dos minutos y se midieron el tiempo de ignición y la pérdida de masa. El impregnado de la madera con sales de boro aumenta la resistencia aparente de la madera a la exposición al fuego. A medida que la densidad de la madera aumenta, los tiempos de ignición se incrementan y, a la vez, se disminuye la pérdida de masa.
... En este contexto, el impregnado con sales de boro es un conjunto de técnicas que pretende optimizar la protección de la madera de su deterioro biológico (Tsunoda, 2001;Temiz et al., 2008;Thévenon et al., 2010;González-Laredo et al., 2015;Obounou-Akong, 2015) y de su variación dimensional (Ayrilmis, 2013;Kotlyarova y Stepina, 2018). En esta tecnología, la retención es el indicador de la cantidad de sustancia que conserva una pieza de madera, por unidad de volumen, después de un tratamiento de impregnación (Berrocal et al., 2004;Koumbi-Mounanga et al., 2015). ...
El objetivo de la investigación fue evaluar si el impregnado de la madera con sales de boro reduce su higroscopicidad y mejora su estabilidad dimensional. En probetas de pequeñas dimensiones de madera de Spathodea campanulata, Fraxinus americana y Albizia plurijuga se aplicó un tratamiento caliente-frío de sales de boro con una concentración de 3%. Se realizaron pruebas de higroscopía y tanto antes como después del impregnado con sales de boro, se analizó la densidad básica, contenido de humedad, higroexpansiones radial, tangencial, longitudinal y volumétrica, puntos de saturación de la fibra, coeficientes de higroexpansión, índice de antiexpansión y relación de anisotropía. Después del baño, las características higroscópicas se modificaron según las especies y las direcciones observadas. El tratamiento mejora la estabilidad dimensional de S. campanulata en 63%, de F. americana en 21% y para A. plurijuga en 18%. Es recomendable investigar la influencia de las características anatómicas sobre las propiedades higroscópicas de estas especies.
... La retención y la penetración en la madera de sales de boro son parámetros que miden la idoneidad de un tratamiento de impregnación, y la aptitud que tiene una especie para su preservación (Berrocal et al., 2004, Koumbi-Mounanga et al., 2015, Pereira et al., 2017. La información al respecto reportada en la literatura es amplia y los resultados son particulares a cada caso de estudio. ...
La impregnación con sales de boro es una alternativa tecnológica para la protección de la madera al biodeterioro. El objetivo de la investigación fue determinar la densidad de la madera, la retención y la penetración de sales de boro en la madera de tres especies angiospermas: Spathodea campanulata, Fraxinus americana y Albizia plurijuga. Con el método baño caliente-frío, se impregnaron probetas de pequeñas dimensiones en concentraciones de 1%, 2% y 3% de trihidróxido de boro y tetraborato de sodio, y se reservó un grupo de control sin tratamiento. Después de la impregnación, las densidades de S. campanulata y A. plurijuga no variaron para las diferentes concentraciones. En cambio, la densidad del grupo de control de F. americana fue diferente a las de las concentraciones de 1%, 2% y 3%. Las cantidades de las retenciones y de las penetraciones de las sales fueron diferentes para cada especie. La retención de sales de boro en las tres maderas disminuye a medida que su densidad y la concentración de sales se incrementan.
... There is considerable data on boron distribution, particularly in solid rod form, and boron compounds have been extensively used in remedial treatments (Dietz and Schmidt 1987;Morrell et al. 1990;Morrell and Freitag 1995;Ra et al. 2001Ra et al. , 2002Morrell 2002, 2005;Cabrera and Morrell 2009;Lebow et al. 2010Lebow et al. , 2013Freitag et al. 2011Freitag et al. , 2013Koumbi-Mounanga et al. 2015). However, there is a lack of information on the distribution of ulexite and colemanite as raw boron minerals in wood. ...
This study evaluated boron diffusion from raw boron minerals ulexite and colemanite with low water solubility in comparison to disodium octaborate tetrahydrate (DOT). Tests were conducted using sugi (Cryptomeria japonica (L.) f. D. Don) sapwood and heartwood blocks conditioned to 30, 60, and 90% target moisture content. The blocks were filled with the boron compounds through treatment holes and diffusion was observed at three assay zones across the blocks after 7, 30, 60 or 90-day incubation period at room temperatures. For comparison, ethylene glycol was also introduced into the holes to elevate boron diffusion. As expected, diffusion increased with increased moisture content and levels were higher at the 60% and 90% moisture levels compared to the 30% level. With some exceptions, boron levels did not follow consistent gradients with distance away from the treatment hole. Incorporation of ethylene glycol helped increase boron levels, even in heartwood blocks. Boron levels were higher from the ulexite source than from colemanite; however, DOT treatments resulted in the highest boron diffusion rates as a result of greater water solubility compared to both raw boron minerals. The results suggest that ulexite together with ethylene glycol may be useful in both sapwood and heartwood materials when kept at high moisture levels for extended periods.
Borate solution was used to treat two sets of Douglas-fir wood samples, one by spraying cross-laminated timbers (CLT) and another set by dip-treating wood in solutions at different retentions. A novel model was developed to explain and predict borate uptake based on dip-treatment parameters. Small-scale CLT samples were prepared using commercial emulsion polymer isocyanate (EPI) and polyurethane (PU) adhesive with dip-treated wood. The effect of adhesive and borate retention on CLT samples were evaluated through adhesion, fire, termite, and decay tests. The adhesion strength of wood was statistically unaffected by borate treatment. Statistical analysis showed that both spray- and dip-treated samples had significantly higher termite and decay resistance and fire performance than the untreated boards. Untreated CLT samples bonded with PU showed a considerably higher inherent decay and termite resistance than untreated specimens bonded with EPI adhesive.
Boron diffusion from preservative pastes made of either ulexite or copper or fluoride compounds was evaluated. The pastes produced were applied to sapwood blocks prepared from Scots pine and conditioned to target moisture contents (MCs) of 30%, 60%, and 90%. The pastes were inserted into the treatment holes in the wood blocks and boron diffusion was determined at three assay zones across the blocks after 7-day, 30-day, 90-day, and 180-day-incubition period at room temperature. Ethylene glycol was also added in some of the paste formulations to improve boron diffusion. In general, boron diffusion from the pastes was improved with increased MC of wood. No steady amount gradients with distance away from the treatment hole were observed for the amount of boron diffusion in the assay zones; however, there were few exceptions. Amount of boron from the pastes with ulexite in wood exceeded well 0.1% boric acid equivalent (BAE) boron threshold in most assay zones and incubation times. Expectedly, boron diffusion from the pastes with ulexite was significantly lower than those from the pastes with borax + copper because of higher water solubility of borax than that of ulexite. The ulexite-based preservative pastes may be useful particularly when wood is kept at high MCs at extended periods.
Refractory wood species like American beech (Fagus grandifolia Ehrh.) and pin oak (Quercus palustris) are difficult to be treated by impregnation with wood preservative formulations or chemical modification agents. They need to be subjected to a preservative process that uses a heat treatment in a deep fryer with vegetable oil at 220 °C for 120 min. Such heat treatment influences several parameters related to the chemical and mechanical wood properties, such as the bending strength of earlywood (Ew) and latewood (Lw) growth rings. In this study, models to estimate bending strengths of Ew and Lw growth rings from near-infrared spectroscopy (NIRS) data have been proposed for oil-heat-treated wood samples of American beech and pin oak. The models were developed using the partition to latent structures (PLS) regression technique. For both species, the bending strength was significantly lower for the heat-treated wood compared to the untreated wood. In the case of beech, the mean bending strength was 112.87 ± 8.55 MPa for the untreated wood samples and 80.78 ± 4.79 MPa for the heat-treated wood samples. In the case of pin oak, the mean bending strength was 99.57 ± 5.34 MPa for the untreated wood samples and 83.69 ± 5.71 MPa for the heat-treated wood samples. All the PLS models were significant at p value < 0.0001. For the Ew tissues, the R2 with the validation data set was 0.78 for beech and 0.95 for pin oak. The corresponding root mean square errors of prediction (RMSEp) were 44.57 MPa for beech and 34.10 MPa for pin oak. The corresponding ratios of prediction to deviation (RPD) were 2.2 and 4.8 for beech and pin oak, respectively. For the Lw tissues, R2 was 0.86 and 0.92 for beech and pin oak, respectively. The corresponding RMSEp were 50.01 MPa for beech and 47.87 MPa for pin oak. RPD values were 5.8 and 3.8 for beech and pin oak, respectively. For both the Ew and Lw tissues and species, B coefficients of the response surface models (ranging from − 108.8 to 195.8) were statistically significant indicating that the models can be used to detect which wavelengths of the spectra have the highest impact on the effect of heat treatment on the bending strength.
This study evaluated boron diffusion from rods made of raw boron minerals, ulexite and colemanite with low water solubility, in comparison with di-sodium octaborate tetrahydrate (DOT). Scots pine (Pinus sylvestris L.) sapwood and heartwood blocks were conditioned to target moisture contents of 30%, 60%, and 90%. The rods were inserted into the blocks through treatment holes and boron diffusion was observed at three assay zones across the blocks after 7, 30, 60 and 90-day-incubation at room temperature. Ethylene glycol was also inserted into the holes to improve boron diffusion. Boron levels increased with increased wood moisture content. With some exceptions, boron in the assay zones did not tend to follow consistent amount gradients with distance from the treatment hole. Boron levels from ulexite rods were higher than those from colemanite rods, with DOT rods with the highest diffusion rates as a result of higher water solubility of DOT than ulexite and colemanite. The results suggest that ulexite-based rods may be useful in the presence of ethylene glycol in sapwood when wood is at high moisture content for extended periods.
A combination of statistical techniques of analyses were used to evaluate the potential of International Commission on Illumination (CIE) lightness (L*), redness (a*) and yellowness (b*) colour space system and near-infrared spectroscopy (NIRS) to assess surface changes in relation with progressive decay of beech (Fagus grandifolia Ehrh.) by wood-inhabiting lignicolous fungi Inonotus hispidus, Trametes versicolor and Xylaria polymorpha. pH effects based modelling predictions of beech earlywood and latewood tissues were also included. Multivariate analysis techniques included response surface optimization, sample-specific standard error of prediction (SEP) method and projection to latent structures partial least squares (PLS) regression. Strong statistical relationships were derived for pH predictions with R² values ranged: from 0.77 to 0.84 for I. hispidus; from 0.77 to 0.84 for T. versicolor and from 0.83 to 0.91 for X. polymorpha. R² values for CIE-based L*a*b* colour space measurements ranged: from 0.43 to 0.69 (L*), 0.66 to 0.76 (a*), 0.42 to 0.53 (b*) for I. hispidus; from 0.59 to 0.69 (L*), 0.69 to 0.79 (a*), 0.64 to 0.79 (b*) for T. versicolor; and from 0.51 to 0.75 (L*), 0.89 to 0.94 (a*), 0.85 to 0.89 (b*) for X. polymorpha. Multivariate technical analysis (response surface analysis, sample-specific SEP, PLS regression) of CIE L*a*b* system and NIRS results should be able to characterize pH effects and surface changes of wood spalted by lignicolous fungi as a quick and reliable non-destructive method relevant to wood-spalting concerns and the forest products industry.
