Maderas. Ciencia y Tecnología

The effects of thermal aging on color and glossiness in UV cured coatings applied to sessile oak

2024-10-04T10:29:08-03:00

Color and glossiness are two important aesthetic properties of wood flooring and wood furniture that significantly affect consumers choice. With time the coating deteriorates altering the surface properties. Understanding these changes is important for furniture industry, impacting design choices, material selection, and long-term maintenance.

The effects of thermal aging (30 °C for 30 days, 60 °C for 60 days, and 90 °C for 90 days) on color parameters (C*, L*, b*. a*, h^o) and glossiness on both perpendicular (⊥) and parallel (║) directions at 20°, 60°, and 85° angles in UV-cured coatings applied on sessile oak were studied. Results show that statistically significant differences were observed in the glossiness values, as well as in C*, b*, a*, L* and h^o. As the temperature and duration of the thermal aging process increased, there was a noticeable increase in the values of color parameters b*, a*, and C*, while the values of h^o and L* decreased. The characteristics of the surfaces exposed to thermal aging have undergone a complete transformation.

Some physical and mechanical properties of particle boards produced with hazelnut husk and astragalus (Astragalus membranaceus) plant

2024-10-09T09:36:33-03:00

In this study, under laboratory conditions, hazelnut husk and astragalus plant were mixed separately into black pine wood chips, and multi-purpose boards were produced from the obtained chips with urea formaldehyde glue. After the hazelnut husk and astragalus plant were dried and ground, they were added to the chip and glue mixture in certain proportions. Hazelnut husk mixture ratios were applied as 100 %; 0 %, 75 %; 25 %, 50 %; 50 %, 25 %; 75 %, 0 %; 100 % to black pine wood chip in the particle board mixture. These ratios were made in the same way for the astragalus plant. From these mixtures, chipboard blanks of 16 mm thickness and densities between 0,68 g/cm³ and 0,72 g/cm³ were produced. Density, moisture content, thickness increase, water intake, bending strength, modulus of elasticity in bending and tensile strength perpendicular to the surface were tested in physical and mechanical experiments. According to the results obtained, as the participation rate of hazelnut shells and astragalus increased, the durability properties of the panels decreased. At the same time, it shows that the technological properties of the panels produced by adding up to 25 % astragalus plant and hazelnut shells to the mixture comply with the standards.

Thermal modification of fast-growing Firmiana simplex wood using tin alloy: Evaluation of physical and mechanical properties

2024-10-11T11:26:49-03:00

Wood is an important structural material, but some undesirable properties limit its application in construction. This study investigated the effect of tin alloy thermal modification (TTM) on selected physical and mechanical properties of Firmiana simplex (Chinese bottletree) wood. Tin alloy thermal modification of F. simplex was performed in a tin alloy bath at two different temperatures (150 ^oC and 210 ^oC for 2 h and 8 h). Physical properties such as swelling, water absorption and density and mechanical properties like modulus of elasticity, modulus of rupture, impact bending, compression strength and Brinell hardness of tin alloy thermal modified and control samples were evaluated. The results showed that tin alloy thermal modification decreased the swelling of the wood to 4,85 %, 1,45 % and 6,99 % along the tangential, radial and volumetric coefficient and water absorption and density decreased to 53,10 % and 290 kg/m³ respectively compared to the control. Modulus of elasticity, modulus of rupture, impact bending, compression strength and Brinell hardness of tin alloy thermal modified F. simplex at 210 °C for 8 h decreased to 6366,1 MPa, 54,9 MPa, 2,7 MPa, 29,4 MPa and 1113,5 MPa respectively compared to the control. In conclusion, the tin alloy thermal modified wood at 210 ^oC significantly affected the physical and mechanical properties of the wood.

Cement-bonded wood panels filled with duroplast sanitary ware wastes

2024-11-07T13:52:22-03:00

The effect of using duroplast sanitary ware waste as a substitute for wood materials in cement-bonded wood panels was evaluated. Utilizing these wastes can provide considerable economic and environmental benefits by reducing the use of wood materials and the deposits in landfills. Cement-bonded wood panels were produced with the replacement of spruce wood materials by the duroplast sanitary ware waste particles in 10 wt%, 20 wt%, 30 wt%, and 40 wt%. The produced panels were examined in terms of physical, thermal, mechanical, and morphological properties and compared with the related standards. Experimental findings demonstrated that water absorption, moisture content, and thickness swelling values of the panels were enhanced by the addition of duroplast sanitary ware waste. The duroplast sanitary ware waste did not affect the density of the panels. The bending strength and the modulus of elasticity of the cement-bonded wood panels can be increased up to 23 % and 5,6 %, respectively, by the addition of 10 wt% duroplast sanitary ware waste particles. However, the internal bond strength and the screw withdrawal resistance values were reduced by an increment in the use of duroplast sanitary ware waste. The scanning electron microscope observation revealed that there was no mechanical interlocking between the duroplast sanitary ware waste and cement, and the formations of voids in the panels increased with an increase in the duroplast sanitary ware waste particle content. The thermal analysis showed that the use of duroplast sanitary ware waste resulted in increased cement hydration products due to the reduction in the wood content of cement-bonded wood panels.

Effect of the heat treatment on the physicochemical characteristics of rubberwood: Results of thermal analysis and FTIR spectroscopy

2024-11-08T10:21:29-03:00

Heat treatment is an environmentally friendly method used to improve properties of rubberwood. In this work, the changes in the chemical composition, thermal behavior and thermal degradation kinetics of heat-treated Hevea brasiliensis (rubber tree) were evaluated using thermogravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The rubberwood samples were exposed to temperatures of 180 °C and 220 °C in air under atmospheric pressure for durations of 15 25 and 35 h. Thermal analysis revealed degradation of hemicelluloses, an increase in the relative proportions of cellulose and lignin in heat-treated rubberwood. The thermal decomposition of rubberwood heat-treated at 220 °C started at a higher temperature compared to untreated wood. A shift in the position of peaks on differential thermogravimetry and differential scanning calorimetry curves of heat-treated samples was observed, indicating changes in the structure of wood polymers. The temperature of heat treatment had a stronger effect on the chemical composition of rubberwood than duration. Significant changes in the chemical composition of rubberwood occurred after the treatment duration of 15 h at both 180 °C and 220 °C. The duration of 25 h and 35 h had no further substantial effect. The isoconversional method of Flynn-Wall-Ozawa was used to determine the kinetics of thermal degradation of untreated and heat-treated rubberwood. It is found that the average values of activation energy in the conversion degree range of 0,05 - 0,65 (the thermal degradation of polysaccharides) increased with increasing treatment temperature and duration. Fourier transform infrared spectra demonstrated alterations in wood polymers.

La regularidad en la anchura de anillos de crecimiento y su empleo en la clasificación visual de la madera para su asignación al sistema Europeo de clases resistentes

2024-11-12T17:55:57-03:00

La homogeneidad en la anchura de anillos de crecimiento de la madera se asocia a una mayor rigidez y resistencia mecánica del material. Por ello, conocer la homogeneidad de la anchura de los anillos sería útil en la clasificación visual de la madera aserrada con fines resistentes. Sin embargo, no está cuantificada la influencia de la homogeneidad en el comportamiento resistente de la madera. En este trabajo se analizó la dispersión de la variable anchura de anillos para determinar su valor predictivo sobre la resistencia y la elasticidad a flexión axial en vigas de madera de Quercus robur (roble europeo). Para realizar el estudio se talaron 26 robles adultos en Galicia (noroeste de España). Los fustes obtenidos fueron aserrados para obtener tablones, que fueron secados al aire y posteriormente fueron cepillados hasta obtener vigas de dimensiones nominales 2000 mm × 100 mm × 50 mm. En una muestra de 52 de dichas vigas se obtuvo el módulo resistente a flexión axial, el módulo elástico a flexión axial, la densidad y la humedad de la madera, así como el porcentaje de albura y la anchura de cada anillo de crecimiento en la sección transversal de cada viga. Las variables descriptivas de la homogeneidad de anillos en cuyo cálculo intervienen los datos de todos los anillos de la viga (desviación típica, varianza, rango intercuartílico) estaban más relacionadas con las propiedades mecánicas. Las piezas con anillos homogéneos presentaban un módulo elástico y una resistencia a flexión estática significativamente mayores, siendo la correlación más destacada la existente entre la varianza de la anchura de anillos y el módulo elástico a flexión (R = -0,41**). No obstante, el valor de las correlaciones obtenidas no justifica la construcción de un modelo predictivo de la elasticidad o de la resistencia mecánica usando solo la homogeneidad de la anchura de anillos como variable predictora. Sin embargo, dado que el comportamiento mecánico se ve significativamente influenciado por la homogeneidad de los anillos, esta característica podría incorporarse en las normas de clasificación visual de la madera de roble con fines resistentes.

Evaluation of wood coating performance and volatile organic compounds

2024-11-14T16:32:54-03:00

The aim of this study was to evaluate the environment-performance relationship of surface coating applications on data obtained by measuring the emission rates of volatile organic compounds in polyurethane and water-based varnishes. For this purpose, polyurethane and water-based varnishes from five different companies were applied to the test samples of Entandrophragma cylindricum (sapele) and Piptadeniastrum africanum (dabema), both widely used in the production of urban furniture. Volatile organic compound, hardness and adhesion strength were measured during application. When evaluated in terms of performance, polyurethane varnishes showed superior hardness, while water-based varnishes demonstrated better adhesion after the UV test. The hardness values of polyurethane varnishes before and after the UV aging test were 15,9 s and 79,403 s, respectively, while forwater-based varnishes were , the values were 114,92 s and 75,406 s. The adhesion values of water-based varnishes were 2,885 MPa and 1,18 MPa before and after the UV aging test, and for polyurethane varnishes 3,13 MPa and 1,05 MPa for. When the environment-oriented results were evaluated, the ; emission values of volatile organic compounds in polyurethane varnish applications were found to be significantly higher than those in in water-based varnishes applications. While the total emission rate of volatile organic compounds detected in polyurethane varnishes was 53,63 mg/Nm³, while only one brand of water-based varnishes showed a measurable emission value, recorded at 0,0057 mg/Nm³. The volatile organic compounds emission values of other water-based varnishes were below the device detection limit (<0,0035 mg/Nm³), and therefore could not be measured.

Antifungal and antitermitic potential of extracts of industrial wood waste from Central Amazon, Brazil

2025-01-07T10:30:40-03:00

Studies on wood durability have highlighted the use of new environmentally friendly substances. In this sense, research carried out with Amazonian forest species is extremely important for the discovery of new bioactive substances from durable wood and its residues. The aim of this study was to evaluate the antitermitic and antifungal potential of extracts obtained from industrial processing residues of wood species from Central Amazonia, Brazil. The sawdust of seven Amazonian wood species were collected to obtain extracts and quantify the extractive content. The extracts produced were tested for inhibition of fungal growth of Rhodonia placenta and Trametes versicolor and impregnated in low natural durability wood known as Simarouba amara (marupa) to verify the effect on wood natural durability against Nasutitermes sp. termites and Gloeophyllum trabeum fungus. Simarouba amara (marupa) wood was easily impregnated and showed satisfactory retention values. The species Buchenavia sp., Dinizia excelsa (red angelim), Hymenolobium flavum (angelim pedra) and Manilkara elata (maçaranduba) exhibited high contents of secondary metabolites. It was observed that the extracts of Roupala montana (louro faia) and Hymenolobium flavum (angelim pedra) exhibited the best performance in inhibiting fungal growth. In the accelerated decay test, marupa wood impregnated with Buchenavia sp. (tanimbuca) extract showed the lowest weight loss after exposure to the fungus Gloeophyllum trabeum. In the termite choice feeding test, wood impregnated with Dinizia excelsa (red angelim) and Buchenavia sp. (tanimbuca) extracts were most consumed and the extracts of Roupala montana (louro faia), Cordia sp., Hymenolobium flavum (angelim pedra) and Manilkara elata (maçaranduba) provided greater inhibition of termite attack. The combination of extracts must be tested in future studies to verify the synergistic effect, in addition to the chemical analyses of the selected extracts.

The effect of cutting direction and water based varnish type on sound absorption coefficient in some native wood species

2024-11-25T10:09:05-03:00

Noise which could be defined as disturbing sound, is becoming a major problem depending with developing technology. Controlling the noise helps raising the quality of life to higher levels. Although the intensity of the noise is not at a level that will affect human health, it should be reduced or eliminated, for better life standart. Due to the adverse effects of the noise level on health; the acoustic properties of living areas require serious consideration. Sound absorption coefficients of the materials used in the interior play an important role in providing sensory comfort depending on the volume. Natural and artificial wood are commonly used materials in interior design, especially in the construction of partition elements. In addition, wood is natural material and it has some important advantages and disadvantages. In this study the sound absorption coefficients of eastern beech and scotch pine trees, which are the most preferred materials in interior design, were investigated. For this pupose, these wood materials were cut superficially and radially according to the intersection directions, then the sample surfaces were varnished with one and two component water-based varnishes that do not contain solvent-based resin. The sound absorption coefficients of the obtained samples were determined by the impedance tube method and the results were compared statistically. It has been investigated that the obtained results could be evaluated statistically within the frequency values, besides, different results could be obtained according to the characteristics of natural wood materials, the direction of intersection and water-based varnish types. According to the findings obtained as a result of the study, it has been suggested that if natural wood material is used indoors, the superficial cross-section of East beech wood should be used according to the direction of intersection, and a two-component varnish should be used according to the varnish type.

Estudio de la mejora de aislamiento a ruido de impacto de soluciones constructivas mixtas CLT / hormigón + neumático fuera de uso en probetas de tamaño reducido

2024-11-29T17:40:28-03:00

La madera contralaminada es un producto industrializado de madera que ha incrementado exponencialmente su uso en la industria de la construcción debido a su eficiencia estructural, su ligereza, su carácter sostenible y su competitividad económica. Así, en los últimos años, se está utilizando este producto para la construcción de edificación colectiva (edificación en altura) en toda Europa, desarrollando un nuevo sistema estructural y constructivo eficiente y de alta calidad. Sin embargo, el uso de estos sistemas constructivos ligeros empleando madera contralaminada, en comparación con los sistemas pesados tradicionales, no presentan un buen comportamiento de aislamiento al ruido de impacto en los suelos de sus construcciones colectivas. Para alcanzar aislamientos similares a los sistemas tradicionales, en el diseño de las estructuras de madera se incorporan nuevos materiales elastoméricos, la mayoría con un coste elevado, en colaboración con materiales de mayor densidad (mortero/hormigón) o multicapa (aislantes acústicos específicos). Este estudio investiga la introducción de materiales elásticos fabricados a partir de neumáticos fuera de uso (NFU), con propiedades elásticas semejantes a los elastómeros actuales, como alternativa para mejorar el comportamiento acústico de estas construcciones ligeras. Para ello, se realizan ensayos en laboratorio de la reducción de transmisión del ruido de impacto sobre especímenes de tamaño reducido, con distintos espesores de manta de NFU, sobre una base de panel mixto de madera contralaminada (CLT) y hormigón. Los resultados muestran mejoras de aislamiento a ruido de impacto (>8 dB) en todos los casos estudiados (mantas de NFU de 4 mm, 10 mm y 20 mm) por encima de los 160 Hz. También se alcanzan mejoras de aislamiento por encima de los 250 Hz al sustituir parcialmente (15%) árido por granalla NFU en la dosificación de la losa de hormigón. La introducción de este tipo de materiales (neumáticos fuera de uso) en la industria de la construcción como aislantes acústicos permite reutilizar, de forma controlada, un material que actualmente genera graves problemas medioambientales por su incontrolado almacenamiento y escaso volumen reciclado. Así mismo, contrarresta las limitaciones acústicas de los productos derivados de la madera, como los paneles mixtos CLT-hormigón, e incrementando las ventajas de sostenibilidad de estos sistemas constructivos de madera.

Radial variation of fiber morphology and wood density of the commercial species Drypetes sp. and Myroxylon balsamum

2024-12-03T22:04:41-03:00

Studying the radial variation of wood density, an essential biophysical property that reflects the quality of commercial species in tropical forests, is crucial. Understanding how these variations relate to wood anatomy provides valuable insights. In this study, we evaluated fiber morphology and radial density variation using X-ray densitometry in two commercial species from southeastern Peru. Ten trees from each species, Drypetes sp. and Myroxylon balsamum (Peru balsam), were analyzed. Fiber characteristics were assessed using macerated tissue, and density profiles were obtained via X-ray densitometry. The results indicate that in Drypetes sp., density decreases from the pith to the bark, whereas Myroxylon balsamum shows no significant radial variation. These findings are important for the efficient use and processing of these species.

Physical, mechanical, and combustion properties of twelve wood species from the Brazilian Amazon

2024-12-13T16:15:02-03:00

Studying the combustibility and physical‒mechanical properties of wood is important for recommending its use in construction. The objective of this study was to evaluate the combustibility, as well as the physical and mechanical properties, of twelve Brazilian Amazonian woods. Species. For each species, the combustibility parameters, fire exposure test, residual mass, loss mass, intact mass, charred area, proximate analysis, basic density, compressive strength and modulus of elasticity were determined. All the evaluated properties were significant affected by the wood species. In the fire exposure test, ignition time ranged from 21 s to 55 s while flame time was between 108 s and 233 s. Residual mass ranged from 60,7% to 82,7%, and intact areas ranged from 28,13 % to 62,68 %. Basic density values ranged from 335 kg/m³ to 889 kg/m³, compressive strength ranged from 29 MPa to 82 MPa, and the modulus of elasticity ranged from 9 GPa to 33 GPa. The wood of Hymenaea courbaril (courbaril), Manilkara huberi (masaranduba), Handroanthus serratifolius (yellow lapacho) was identified as the most suitable for structural components, ensuring greater safety against possible fires. Short-term fire exposure tests, particularly the ignition time parameter combined with residual mass and intact area, are key for assessing wood resistence to fires.

Mineralization of chemically treated sawdust and its use as aggregates in fly ash-based geopolymer composites

2025-01-02T12:30:25-03:00

This study presents an innovative approach to wood mineralization through various pretreatments, focusing on the application of chemically treated sawdust as aggregates in fly ash-based geopolymer composites. Eucalyptus wood sawdust underwent five distinct treatments: cold water washing (CWW), hot water washing (HWW), sodium hydroxide washing (SHW), calcium hydroxide mineralization (CHM), and Portland cement mineralization (PCM). Comparative analyses revealed that the properties of these geopolymer composites were comparable to, or exceeded, those achieved with traditional sand aggregate. The incorporation of the pretreated wood aggregates resulted in geopolymer composites with comparable compressive strength values at 30 and 90 days, with further strength improvements after aging especially for composites treated with HWW or SHW. Additionally, these composites exhibit the formation of a mineral layer on the wood surface, confirming successful mineralization. This study concludes that HWW and SHW treatments significantly enhanced the compatibility between wood and the geopolymer matrix, paving the way for developing light weight geopolymer composites with promising applications in the sustainable building materials.

Some physical and mechanical properties of particle boards produced from industrial wood chips and Scots pine (Pinus sylvestris) cones

2025-01-02T13:09:03-03:00

This study investigated the potential use of Scots pine cones as an alternative raw material to larch wood chips for particle board production. Due to the increasing scarcity of forest resources, exploring alternative raw material for the forest industry has gained importance in in recent years. Particle boards were produced in laboratory conditions by blending industrial wood chips with Scots pine cones in varying proportions (25 %, 50 %, 75 % and 100 %) and usingr urea formaldehyde glue. The adhesice mixture contained 55 % urea formaldehyde glue and 33 % ammonium chloride as a hardener. Te production parameters included a press temperature of 150 °C, a press time was 7 minutes, and a press pressure of 2,4 MPa to 2,6 MPa. The resulting boards had a thickness of 16 mm and a density ranging from 730 kg/m³ to 740 kg/m³. Tests for thickness iswelling, water absorption, , bending strength, modulus of elasticity and tensile strength perpendicular to the surface were conducted. Results showed that the physical and mechanical properties of the boards containing up to 25 % Scots pine cone met the required standards.

Efficiency analysis of the Chilean sawmill industry

2025-01-14T17:49:08-03:00

Chile plays a significant role in global sawn wood production, ranking 14th in total roundwood and 10th in coniferous sawn wood production in 2022, contributing significantly to the demand for wood products. In the same year, the country exported wood products worth a remarkable $US 6.682 million of, underscoring its importance in the global wood industry. Despite its prominence, the sector has faced significant including mega forest fires and the COVID-19 pandemic, which have adversely affected its performance. One notable issue is the decline in the number of active sawmill units, with only 61 currently producing sawn wood with structural characteristics. The highlights the pressing need to quantify and optimize efficiency within the industry. To address this, Stochastic Frontier Analysis a valuable mathematical framework for evaluating industry efficiency, was employed. Using a dataset compiled by the Chilean Forestry Institute and applying the Stochastic Frontier Analysis methodology, this research assessed the average efficiency of the Chilean sawmill sector. The analysis, based on two different models, consistently revealed a decline in average efficiency during the pandemic. Furthermore, it identified a longitudinal gradient in the efficiency of sawn wood production, with technical inefficiency decreasing towards the southern regions of the country. However, the study did not find direct evidence of a correlation between productivity and the production scale of sawmills. Instead, cost factors, including raw materials, labor, and supplementary expenses, emerged as critical areas requiring careful attention to improve the overall efficiency of the industry.

Efecto del rectificado de cuchillas sobre la calidad superficial de madera cepillada de Pino radiata

2025-01-24T17:24:52-03:00

La operación de rectificado permite obtener una órbita de corte única para todas las cuchillas instaladas en un cabezal rotativo. Durante este proceso, una piedra esmeril pasa sobre los filos de las cuchillas en movimiento, generando un bisel cuyo ancho varía dependiendo de la intensidad de la rectificación. Una adecuada selección del ancho de bisel es esencial para garantizar un corte homogéneo y de calidad en la superficie de la madera. Este estudio tuvo por objetivo evaluar como el ancho de bisel y el nivel de desgaste de las cuchillas (representado por la longitud de cepillado) influyen en el consumo de energía y en la calidad superficial de la madera de pino radiata. Para ello, se probaron cuatro anchos de bisel y cuatro niveles de desgaste de cuchillas, utilizando la resistencia al cizalle de uniones encoladas como indicador de la calidad de la superficie. Los resultados revelaron que tanto el ancho de bisel como la longitud de cepillado tienen una relación directa con el consumo de energía, mientras que presentan una relación inversa con la resistencia al cizalle. En función de estos hallazgos, se recomienda emplear un ancho bisel de 0,3 mm para el cepillado de madera de pino radiata, ya que presento menor consumo de energía y mayor resistencia al cizalle.

Surface quality of planed tangential and radial sections of thermally modified Silver fir wood

2025-01-30T15:28:47-03:00

The quality of glued or coated wood largely depends on the strength of the bond between the adhesive or coating and the wood surface. The roughness of the surface plays a crucial role, as it significantly impacts both the wettability and the effectiveness of the bond. This study was carried out to provide information on the surface roughness of Abies alba (silver fir) planed after thermal modification, focusing on the anisotropic behavior of the material, particularly along the radial and tangential sections. Four groups of eight samples without defects were prepared. Half of the samples of each group presented clear tangential section while the other half presented clear radial ones. One group was used as control and the others were heated, applying three different temperatures 160 °C, 190 °C and 220 °C, at atmospheric pressure for 3 hours. The control and the three other heat-treated groups of samples were processed along the grain by a planer machine. 10 m/min feed speed was applied. Surface roughness measurements were performed with a stylus profilometer. A positive correlation was observed between the modification temperature and the roughness of the surface. It was noted that the radial section of natural wood presented greater roughness than the tangential one. For temperatures lower than 200 °C the roughness of both sections resulted almost equal, while above this temperature the roughness of the radial section increased over 20 % compared to the roughness of the tangential one. The information provided by this study is very important for the gluing and finishing processes that can be applied to thermally modified wood.

Physical and mechanical aging of wood-plastic composites. Non-destructive methods for quality control

2025-01-30T16:44:22-03:00

This study investigates the relationship between laboratory aging, physical and mechanical changes, and the outcomes of non-destructive testing. A total of 45 composite specimens containing 60 % wood fiber, 35 % low-density polyethylene, and 5 % additives were tested. A laboratory aging process, consisting of water immersion at 20 ºC and 50 ºC for a total of 56 days, was applied to the specimens. During the aging process, several batches of specimens were extracted and tested to measure their physical (density) and mechanical properties (bending strength and modulus of elasticity). Non-destructive testing, including ultrasound and stress wave devices, a screw withdrawal resistance meter, and a penetration tester, were employed. Results indicated that temperature had a greater influence on the WPC deterioration than humidity. A decrease in density (2 % - 4 %) and a significant reduction in mechanical properties (20 % - 60 %) were observed. The non-destructive methods used proved to be reliable estimators of composite properties, especially ultrasound wave propagation, confirming previous findings on other materials.

Use of Eucalyptus urophylla waste as raw material in composite particleboards

2025-02-11T22:23:56-03:00

Eucalyptus urophylla (ampupu) is one of the most commonly cultivated species in Brazil for industrial scale particleboard production. This study investigates the reuse of Eucalyptus urophylla sawmill waste as a raw material for particleboard manufacturing, addressing the growing need for sustainable material solutions. Without prior particle homogenization, two manufacturing approaches were tested: single-layer and three-layer boards. Using a castor-oil-based polyurethane resin (10 % for single-layer and 12 % for three-layer boards), the panels were pressed at 5 MPa for 10 minutes at 100 °C. Performance evaluation under standards revealed that multilayer panels demonstrated superior mechanical and physical properties, while single-layer boards did not meet classification standards, highlighting the benefits of optimizing wood waste in multilayer compositions.

Construction and performance of a 1:2 scale timber structure under standardized load tests

2025-03-21T13:00:48-03:00

Timber’s growing prominence in both new construction and heritage rehabilitation demands reliable methods to evaluate structural safety. However, most current load-testing protocols target concrete and overlook key timber-specific characteristics such as creep, delayed deflection, and service classes. This study addresses these gaps by investigating a 1:2 scale two-story timber prototype subjected to monotonic (UNE-EN 380) and cyclic (DAfStb) load tests. A comprehensive array of sensors captured time-dependent deflections and post-unloading recovery, revealing pronounced creep effects and highlighting the limits of existing standards to account for timber’s long-term deformation. Although cyclic tests can be completed more quickly, they do not adequately track delayed deflection behaviour crucial to timber structures; by contrast, the sustained-load protocols demanded by monotonic tests provide meaningful insights into creep and sostenibility considerations (such as water usage). These findings underscore the need to develop updated, consensus-based load-testing guidelines that better reflect timber’s unique mechanical response. Such standards would enable more accurate assessments of timber floors, roofs, and frames in both historic and contemporary contexts.

Glulam bonding quality of chromated copper arsenate treatment applied to Pinus elliottii wood and three structural adhesives

2025-03-27T17:09:25-03:00

Glued laminated timber is an alternative gaining prominence in the Brazilian construction field. As a result, industries seek ways to improve the quality of their products, focusing on the wood used, the adhesive, and the manufacturing process. The aims of this study are to evaluate the effect of the preservative treatment chromated copper arsenate (CCA) as a preservative treatment on the gluing quality of Pinus elliottii (slash pine) glued laminated timber (Glulam) elements. For this purpose, Glulam was compared with and without CCA treatment, using Cascophen RS 216 -M, Jowat 686,60 and AG 101 adhesives to bond the laminated wood specimens. The glue quality was evaluated through delamination and shear strength tests of the glue lines based on the test method, following the European standard. The delamination results indicated that there were no significant differences between those obtained for the combinations of wood treated with CCA and wood in natura. The results of the shear tests on the glue lines revealed significant differences when comparing the performance of wood treated with CCA to that of untreated (in natura) wood. Specifically, when using Cascophen 216-M and polyurethane AG 101 adhesives, the treated wood demonstrated notably different shear strengths. This indicates that the preservative treatment with chromated copper arsenate alters the bonding effectiveness of these adhesives, highlighting the importance of selecting appropriate adhesive formulations for treated wood to ensure optimal bonding quality. The only species/adhesive combination that showed a delamination limit lower than 4 % was the one that considered natural wood glued with Cascophen 216-M adhesive. To confirm these results is essential a complementary study evaluating the viscosity of the resins used.

Estudio comparativo de productos de madera laminada unidos con distintos tipos de clavijas

2025-03-31T13:20:35-03:00

La búsqueda de soluciones constructivas sostenibles ha impulsado el uso de productos de madera masiva como alternativa a componentes estructurales de hormigón armado y acero. En este contexto, el presente trabajo informa sobre el comportamiento estructural de productos de madera laminada construidos sin adhesivos y con madera de pino uruguayo (Pinus taeda) de rápido crecimiento. Para la fabricación, se utilizaron lamelas C14, unidas mediante tarugos de madera de 20 mm de diámetro, clavos de madera y clavos de acero colocados neumáticamente, de 5,3 y 3,2 mm de diámetro, respectivamente. Se evaluaron dos patrones de clavado, en línea recta horizontal y zigzag, y tres espaciamientos entre clavijas, 300 mm, 250 mm y 150 mm. Se realizaron ensayos de corte perpendicular a las fibras en conexiones de madera y ensayos de flexión en cuatro puntos en paneles de tamaño estructural, y se obtuvieron el módulo de deslizamiento y las propiedades de flexión, respectivamente. Las conexiones con clavos de madera presentaron valores de módulo de deslizamiento significativamente superiores (2,54 kN/mm) a las conexiones con tarugos de madera (1,47 kN/mm) y con clavos de acero (1,25 kN/mm). Los resultados de flexión indicaron que la resistencia (16,8–31,6 MPa) y la rigidez (6213–8103 MPa) de los paneles con tarugos de madera, clavos de madera y clavos de acero no mostraron diferencias significativas y son similares a los valores de las piezas individuales que los conforman. Los hallazgos encontrados sugieren que la madera laminada fabricada con pino de rápido crecimiento unida mediante clavijas de madera en configuraciones superficiales aparece como una solución estructural viable para entrepisos y techos en el contexto de sistemas constructivos sostenibles.

Preliminary study of Acacia dealbata logs for use in construction: Visual characterization and non-destructive testing

2025-04-03T14:52:37-03:00

This study provides a preliminary mechanical characterization of minimally processed Acacia dealbata logs to assess their potential valorisation as a by-product of invasive species management. A total of 45 logs (90–143 mm diameter) from two harvest seasons groups, spring (17 logs, 2.0 m) and winter (28 logs, 2.4 m), were visually selected and evaluated for dynamic modulus of elasticity using longitudinal stress wave and transverse vibration tests. Testing was conducted in two moisture content states: air-dried (> 12%) and kiln-dried (≈ 12%). Significant differences between the two groups necessitated separate analyses and suggested a relationship between harvesting season and physical-mechanical properties. Although dynamic properties increased post-kiln drying, initial dynamic modulus of elasticity values were lower due to elevated initial moisture content. Visual characteristics exhibited weak correlations with dynamic properties, whereas high correlations were observed between adjusted dynamic modulus of elasticity values for both moisture states (r > 0,90 for longitudinal stress wave; r > 0,70 for transverse vibration). Adjusted dynamic modulus of elasticity values (18,29/14,00 GPa for longitudinal stress wave; 16,32/12,69 GPa for transverse vibration) were comparable to prior studies and support a potential classification of Acacia dealbata (mimosa) logs for structural applications.

Production of value-added decorative furniture items from recoverable wood wastes from construction site

2025-04-03T16:56:02-03:00

The cost of wood and non-wood lignocellulosic materials continues to escalate yet the demand keeps rising at the face of the climate change problem aggravated by unsustainable tree removal across the world. Lignocellulose waste is unavoidably generated during construction. The viability of producing decorative furniture items from recoverable wood wastes from a construction site was investigated. Ten construction sites were randomly chosen, for on-the-spot assessment to obtain information on characteristics of bio-wastes originating from construction sites. A 6-flat-storey building was selected for an in-depth study. Data were collected on the composition of bio-wastes, Retrievable volume, and exposure and deterioration status. Redundant fragments of wood wastes were retrieved and processed into glue-laminated panels, constituting intermediate raw material that was used for manufacturing three decorative furniture items. Although a wide range of bio-wastes was generated at the construction sites, wood, bamboo, and medium density fibreboard, wastes were generated more substantially and in decline order, respectively. Most of the bio-wastes had largely deteriorated, but about 60 % of the wood wastes can still be recovered for re-use. Re-using recovered wood for decorative furniture items may save as much as 73 % of the actual cost of wood needed for production, with a negligible increase in labour cost. Glued-laminated panels were used to manufacture shelves installed for office use. The study suggested that more values may be obtained from bio-waste reuse if retrieved without delay.

Optimization and characterization of wood decay mushroom Ganoderma adspersum extract: A comparison between response surface methodology and artificial neural network-ant lion algorithm

2025-04-14T12:50:29-04:00

In this study, the bioactive properties of Ganoderma adspersum, a wood-decaying mushroom, were investigated. The study was designed in three steps: an experimental study, optimization of extraction conditions, and determination of bioactive properties of the optimum extracts. The main research problem was to determine the most effective extraction conditions to maximize the bioactive potential of G. adspersum using advanced optimization techniques. The extraction conditions were designed according to the I-optimal design and optimized using both the response surface method and the integration of artificial neural networks–ant lion algorithm. In the third step of the study, the bioactive properties of the two estimated extraction conditions and the extraction condition providing the highest total antioxidant status value obtained from the experimental studies were evaluated. Antioxidant activity, total phenolic and flavonoid content, antimicrobial properties, anticholinesterase activity, and phenolic content of three different optimum extracts were determined. As a result, the optimum extraction conditions suggested by artificial neural networks–ant lion algorithm optimization showed the best overall bioactive activity, highlighting the effectiveness of hybrid artificial intelligence-based models in bioactive compound extraction processes.