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With a growing emphasis on eco-friendly building materials, wood strands-rock wool-cement boards (WRCB) offer a promising solution due to their composition of renewable wood fibers and cementitious binder. This study delves into the intricate balance between sound absorption, thermal insulation, and cost-effectiveness of WRCB, all of which are crucial factors shaping indoor comfort, energy efficiency, and the economic viability of constructions. WRCB incorporating wood strands, Portland cement, rock wool, and calcium chloride were manufactured at various thicknesses (20–60 mm) and densities (400, 500, and 600 kg/m³). The WRCB exhibited sound absorption average (SAA) and effective thermal conductivity (K eff) values ranging from 0.28 to 0.56 and 0.285–0.381 W/(mK), respectively. These results underscore the remarkable SAA and K eff of the panels, showcasing their potential as sustainable construction materials. Notably, WRCB with thicknesses ranging from 30 mm to 50 mm and densities of 400–500 kg/m³ exhibited nearly ideal absorption levels between 1000 and 2000 Hz, indicating their practical suitability for speech-related scenarios in architectural environments. The utilization of the Response Surface Methodology allowed the optimal conditions for maximizing SAA while simultaneously minimizing K eff and cost to be identified through the optimization process. A density of 452.8 kg/m³ and a thickness of 37.8 mm were determined as the optimal parameters. Under these conditions, the resultant SAA reached 0.554, with a corresponding cost of 1724 IRR and K eff of 0.317 W/(mK). The results also demonstrated the significant impact of thickness and density on the acoustic and thermal performance of the WRCB. The acoustic performance of WRCB was further analyzed through predictive modeling using the Johnson-Champoux-Allard (JCA) and Delany-Bazley (DB) models. The results revealed that the JCA model exhibited superior predictive accuracy compared to the DB model. • Wood strand-rock wool-cement boards for sound absorption and thermal insulation. • WRCBs offer acoustic comfort, energy efficiency and economic viability in buildings. • SAA and K eff values of the panels range from 0.28 to 0.56 and 0.285–0.381 W/(mK). • Optimal WRCBs achieved promising SAA and K eff of 0.554 and 0.317, respectively. • Interaction effects of thickness and density on SAA, K eff and cost was investigated. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach using wood fiber/PLA composite microperforated panel (WFCMPP) for indoor sound absorption purposes. WFCMPP, comprising rubber tree chip-derived fibers and a polylactic acid (PLA) matrix, with the dimensions of the rubber tree chip-derived fibers ranging from 0.5 to 1 mm, demonstrated promising sound absorption coefficients comparable to other natural fiber composite microperforated panels. The maximum sound absorption coefficient was recorded at 0.989 with a resonance frequency of 1416 Hz when the wood fiber composition was 30 %. The study also investigates the impact of wood fiber composition on sound absorption, revealing a linear relationship between fiber content and both porosity and sound absorption. The peak sound absorption coefficient of WFCMPP remained almost identical at different air gap thicknesses, showcasing the versatility and effectiveness of the samples. Additionally, the performance remained robust even with variations in air gap size. Scanning electron microscope analysis confirms the irregular porous structure and complexity contributing to enhanced sound absorption. WFCMPP presents a sustainable and effective alternative for acoustic applications, combining sound absorption performance with environmental considerations. [Display omitted] • Microperforated panels (MPPs) were fabricated from wood fiber/PLA composite using conventional machining. • Sound absorption of wood fiber/PLA MPPs (WFCMPP) was measured using an impedance tube. • All samples showed excellent absorption, with coefficients exceeding 0.9 between 1,400 and 1,470 Hz. • Porosity and surface morphology analyses were conducted to verify the complex structure of WFCMPP. • WFCMPP's sound absorption performance was comparable to other natural fiber-based MPPs. [ABSTRACT FROM AUTHOR]

Joists with corrugated panel webs are a structural solution that has been little tested on wood-based materials. This study has the objective to develop the potential of wooden I-joists with two different web configurations. Joists with corrugated webs were manufactured and tested in bending tests to determine their mechanical properties. The shear capacity of a joist with a single-panel corrugated web is only 45 %, while a joist with a double-panel corrugated web offers 87 % compared with commercial I-joists. The failure mode of joists is initiated by buckling, followed by the creation of diagonal tension lines in the corrugated web. • New wooden I-joists with corrugated panel web were manufactured and flexure tested. • Shear capacity of a joist with a single-panel corrugated web is only 45 % of that of a commercial I-joist. • Shear capacity of a joist with a double-panel corrugated web is over 87 % of that of a commercial I-joist. • Doubling the I-joist web into a corrugated panel improves shear capacity by a factor of 1.93. • The shear failure mode of joist with corrugated panel web takes the form of local, global, and interactive buckling and diagonal tension lines. [ABSTRACT FROM AUTHOR]

Wood is an attractive bio-based building material whose properties are often affected by environmental moisture, ultraviolet, and fungi. Chemical modification is an effective way to improve wood properties (e.g. , dimensional stability and decay resistance) and thus extends the service life of its products. However, traditional chemical modifiers often contain mild toxicity or volatiles, which harms the operator and environment. Herein, a carboxylated sucrose (CS) was prepared by a green synthesis route using natural compounds (sucrose and malic acid) and used to enhance the properties of wood. The CS penetrated the wood through vacuum-pressure impregnation, which can self-polymerize and be deposited in the cell lumen and chemically bonded to cell wall components, thus efficiently sequestered within the wood. The CS treated wood (CS-wood) exhibited excellent dimensional stability with 41 % of ASE due to its cross-linking with cell walls. Besides, the modulus of elasticity and compressive strength of CS-wood increased by 21 % and 20 % compared with untreated wood, respectively. Notably, CS can help extend the wood service life by limiting the adsorption and migration of moisture in wood cells to improve the UV and decay resistance of the wood. This whole-process friendly approach to preparing biomass-derived CS modifiers effectively improved wood properties, which may provide innovative concepts and insights for wood modification research. [Display omitted] ● Carboxylated sucrose (CS) was synthesized by a green route from natural compounds. ● The CS treated wood exhibited excellent dimensional stability with 41 % of ASE. ● The UV and decay resistance of the wood was remarkably improved after CS treatment. ● Non-toxic CS improves decay resistance of wood by limiting water in the wood cells. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride cement (MOC) is a promising substitute for formaldehyde-based adhesives for wood bonding due to its low carbon footprint, formaldehyde-free and flame-retarding natures. However, the poor water resistance and weak interfacial compatibility with wood limits their practical applications. Herein, inspired by mussels, we reported an eco-friendly and versatile strategy to develop MOC-based wood adhesive with desirable water resistance, high adhesive strength and strong bonding interface. Amino-functionalized sepiolite (KSep) was selected as the nano fillers and inorganic fibers to enhance the structural compactness and resist cracks propagation of MOC. Gallic acid (GA) was employed as the crosslinking agent to induce multiple reinforcement network based on phenol-amine crosslinking and ion chelation in MOC system. The synergy of inorganic fiber enhancement and multiple reinforcement network not only strengthens the cohesive properties, but also enhances the physical anchorage and chemical reactions at the bonding interface, thus endowing MOC with outstanding adhesion ability to wood. The MOC/KSep/GA composite exhibits dry and wet shear strength of 2.63 MPa and 1.75 MPa, being respectively 14.85 % and 42.28 % higher than those values of the pristine MOC. This strategy provides a new route for the development of high-performance cementitious materials and adhesives. [Display omitted] • An eco-friendly, flame-retardant and non-formaldehyde wood adhesive was proposed. • A mussels-inspired magnesium oxychloride cement was prepared as wood adhesive. • The amino-functionalized sepiolite was used as inorganic fiber reinforcer. • A multiple reinforcement network based on phenol-amine crosslinking was formed. • Adhesive showed good adhesion strength and strong bonding interface. [ABSTRACT FROM AUTHOR]

The combined effect of pine wood waste panels resulting from the different industrial processes to produce window frames and double glazing systems with monolithic aerogel of different hydrophobicity in the gap on the heating, cooling, and artificial lighting energy demand of a typical 70 s residential building in different climatic conditions is evaluated. The scraps obtained from the production of the innovative transparent glazing systems are used to fabricate eco-sustainable panels using natural flour-based glue. A thermal conductivity value of the opaque panels equal to 0.077 W/mK is measured by means of a thermal flux meter methodology. As regards the glazing systems, thermal resistance values of 0.86 and 0.92 m2K/W are measured for hydrophilic HY 0 and hydrophobic HY 10 unit, respectively; as a consequence, a thermal transmittance reduction equal to 65–67 % is obtained with respect to the double glazing unit with air in the gap. However, visible transmittance equal to 0.66 is measured as increasing hydrophobicity with respect to 0.81 of the conventional air glazing unit (reduction of 16 and 19 % with HY 0 and HY 10, respectively), as measured by means of a large integrating sphere spectrophotometer. The experimental data measured on eco-sustainable opaque panels and innovative transparent solutions are implemented in dynamic simulation models. The results show an annual heating energy demand reductions (in the 17 (Bolzano) – 39 % (Palermo) range) and cooling (in the 2 (Bolzano) – 11 % (Rome) range) in different climatic areas. Hydrophobicity has a negligible influence on the results. On the other hand, the energy demand for artificial lighting is not affected by the investigated solutions (maximum increase of 10 % is obtained in Bolzano with hydrophobic glazing system). This work is preparatory for the future possibility of starting a production chain of wood fiber insulating panels in the area, which will be in case fabricated at industrial scale in order to reduce the environmental impacts in the construction process of a building in a circular economy perspective and to improve the energy efficiency of the building envelopes by means of innovative materials. • the recovery of wood waste resulting from the industrial processes is encouraged. • combined effect of eco-sustainable panels and innovative are investigated. • experimental data are used in dynamic simulations. • heating energy demand reduction up to 24 % is obtained in temperate climate. • the study is the basis for the development of industrial wooden waste chains. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to utilize the wastes of wheat straw, goose down and wood industry and bring them into the economy. A sustainable insulation material was produced using environmentally friendly water-based PVA styrene acrylic copolymer as a binder with these wastes. In the study, mechanical properties, acoustic absorption and burning resistance were examined. Response Surface Method Box-Behnken Design (RSM-BBD) was used for experimental design and optimization. As a result of mechanical tests, it was seen that the binder ratio had a very high effect on mechanical strength. It was observed that the acoustic absorption coefficient increases with the increase of each of wheat straw, wood shaving, goose down and water-based copolymer resin. Styrene acrylic copolymer was found to be suitable binder for agricultural wastes. AL 2 O 3 , MgO, and Zn[B 3 O 4 (OH) 3 ] were used to increase fire resistance. The results revealed that these compounds can be used as fire retardants for materials consisting of cellulosic-based fillers and water-based polymer binders. The best combustion results for the material were achieved with Zn[B3O4(OH)3]. Flame retardants reduced cellulosyl and polymeric mass loss by up to 61.5 %. It was observed that the best fire resistance was F27 sample, which started to extinguish after two minutes despite the continuation of the fire and extinguished immediately after the fire was removed. The study revealed that such materials can rival conventional materials for green credentials, technical, economic, and environmental aspects. • Styrene acrylic copolymer was found to be suitable binder for agricultural wastes. • Flame retardants reduced cellulosyl and polymeric mass loss by up to 61.5 %. • The best combustion results for the material were achieved with Zn[B 3 O 4 (OH) 3 ]. • Al 2 O 3 , MgO and Zn[B 3 O 4 (OH) 3 ] were suitable fire retardants for sample materials. • Wheat straw, sawdust, goose down and polymer had a good effect on sound insulation. [ABSTRACT FROM AUTHOR]

Unilateral surface compression in wood presents notable benefits, including reduced wood volume loss and energy consumption, rendering a highly promising and extensive utilization. However, shortcomings in compressed wood arise due to unclear gas pressure, temperature, and moisture content distribution within the wood during hot pressing. In this paper, the temperature and pressure distribution were analyzed utilizing an optical fiber temperature and pressure measurement system within the wood during hot pressing. Moreover, the moisture content, stress and strain in each layer at the end of hot pressing were discussed extensively. The results showed that the wood surface layer (SL) and subsurface layer (SSL) maximum temperature values were similar even with different layer thicknesses. Under sealing conditions, SL and SSL temperatures were generally 6 ℃ to 7 ℃ higher compared to unsealing conditions. The gas pressure maximum value exhibited an opposite order, gradually transferring to the core layer (CL) and declining as the processing time extended. During compression treatment, moisture migrated from the hot end to the cold within the wood. The moisture content displayed significant differences between the middle and end parts of the wood under unsealed conditions, with the disparity becoming more pronounced further away from the hot end. The transition region of the compressed wood served as a stress concentration area, experiencing the highest levels of stress. The dense region followed with the second highest stress levels, while the un-densified region exhibited the least amount of stress. Under the same process parameters, the thickness had little influence on the distribution of dense layers. [Display omitted] • The transition region of the compressed wood served as a stress concentration area. • Under the same process parameters, the thickness had little influence on the distribution of dense layer. • The description of temperature and gas pressure distribution during the preparation of unilateral surface densification wood has been successfully achieved. [ABSTRACT FROM AUTHOR]

In this paper, a symbiotic experimental and numerical approach is used to determine the structural performance parameters and analyse the failure behaviour of a novel high-performance hybrid steel-grout connector for cross-laminated timber (CLT) panels. The connector is composed of a steel rod, which is embedded into a 3-ply CLT panel with the aid of a thick layer of epoxy-based grout. Material tests on wood from the two lumber grades present in the CLT panels, and on the epoxy-based grout were conducted to provide an insight into their mechanical behaviour. Forty-two monotonic push-out shear tests were conducted on connectors, varying the grout layer diameter thrice and the loading direction twice. A finite-elements (F.E.) model for the connector was developed in the F.E. software ANSYS and calibrated based on experimental observations on materials and connectors. The tested connectors proved to be strong and stiff in both loading directions, with a maximum slip modulus of 111 kN/mm, yield resistance of 177 kN, and maximum resistance of 192 kN. The diameter of the grout was found to significantly influence all three performance parameters, and much so when the connector was loaded in the direction perpendicular to the CLT face layers. The developed F.E model was able to capture the slip modulus, yield resistance, and maximum resistance with an accuracy above 95 %. The F.E. model also sheds light on the structural performance, yield mechanism, and failure propagation for connectors. • The grout diameter positively influences the slip modulus, yield, and ultimate resistance of connectors • The effect of the load orientation on the structural performance of connectors decreases as the grout diameter increases • The finite-element model developed is able to capture the load-slip behaviour and failure mode of connectors with an error below 5 % [ABSTRACT FROM AUTHOR]

Energy assessment of buildings is important to many applications including energy labeling and building retrofit strategies. However, thermal transmittance, which is key to energy assessment, poses a challenge for in-situ evaluation. To address this, we present an exploration of theoretical and experimental data correlating thermal conductivity and dielectric properties of multilayered assemblies consisting of wood-frame construction materials. We experimentally found an R2 score of 0.88 between thermal conductivities and dielectric constants for 26 small-sized assemblies. We predicted their thermal conductivity based on dielectric properties and obtained an R2 score of 0.95 between experimental and predicted results. • Experimental study correlating physical properties of multilayered materials. • Strong correlation between thermal conductivity and dielectric properties found. • Dielectric properties used to infer thermal conductivity of multilayered assemblies. • Showed potential to use dielectric properties for buildings energy assessment. [ABSTRACT FROM AUTHOR]

Stable super-hydrophobic modification can extend wood service life and expand its application. Inspired by lotus leaf effects, this study proposed a new environmentally friendly strategy by using biomass-derived furfuryl alcohol (FA) and nano-particles based on organic-inorganic hybridization. The FA was pre-polymerized on wood surface followed by in situ growth of stearic acid modified nano-TiO 2. The modified wood (PFT) behaved super-hydrophobic, and the water contact angle and rolling angle reached 157° and 3.2°. This was mainly because a micro-nano, coral-like and rough structure was fabricated on wood surface with hydrophobic furfural resin, suggested by SEM, AFM and FTIR results. The PFT presented prominent durable super-hydrophobicity after mechanical abrasion, tape peeling and acid destruction owing to the fixation effects from furfural resin on nano-TiO 2. The dimensional stability was remarkably improved and the volumetric change after 24 h water absorption decreased by about 90 %. This was primarily because ① super-hydrophobic wood had low attraction to water molecules, ② most water paths were blocked by hydrophobic modifiers, ③ some cell walls were bulked and many sorption sites became inaccessible. Besides, the PFT exhibited excellent self-cleaning performances and improved surface hardness and thermal stability. Such stable and durable super-hydrophobic material may have long service life and meet demands for application under harsh environments. [Display omitted] • A bio-inspired green strategy for creating superhydrophobic wood is proposed. • Synergies of furfural resin and nano-TiO 2 are used for upgrading low-quality wood. • The fabricated superhydrophobic wood has excellent durability and stability. • The modified wood has improved hardness, dimensional stability and thermal stability. • Relation between wood property increase and structure is built for mechanism analysis. [ABSTRACT FROM AUTHOR]

Pilot-scale oil heat treatment was conducted to enhance the quality of poplar wood obtained from a fast-growing plantation. Three target temperatures, namely 180, 190, and 200 ˚C, were chosen for the oil heat treatment process. Clear, small specimens were cut from the lumber, following the prescribed standards for assessing wood quality. Light microscopy revealed the ruptures and deformation of the wood cell wall as the treatment temperature increased. The volumetric swelling of the treated specimen decreased proportionally with the increase in treatment temperature. The impact of oil heat treatment on the mechanical properties of wood varied depending on the specific type of mechanical strength and processing temperature. The modulus of rupture, toughness, and hardness of the treated specimens drastically decreased at 200°C. However, the specimens treated at 200°C exhibited much lower mass loss during the fungal decay test. The results of the analytical test showed an increase in the crystalline cellulose content and thermal stability of the treated wood, due to the thermal degradation of hemicelluloses and amorphous regions of cellulose. Overall, it is concluded that oil heat treatment of poplar wood in the optimal temperature is an efficient approach to upgrade its quality with minimal reduction in mechanical strength. [Display omitted] • The potential of a pilot - scale oil heat treatment (OHT) was evaluated to upgrade the quality of poplar wood. • Higher treatment temperature resulted in higher durability and hydrophobicity. • Mechanical properties differed depending on the heating temperature. • Hemicellulose degradation was identified as a key factor driving changes in wood characteristics during soybean oil heat treatment. [ABSTRACT FROM AUTHOR]

The controllability of the position and thickness of the compressed layer in the sandwich compression wood is primarily based on the yield stress distribution during a hydrothermal treatment. In this study, the variation law of the yield stress of poplar wood was analyzed in the moisture content (MC) range of absolute dryness to saturation and the temperature range of 30–210℃. A prediction model of wood yield stress response to MC and temperature was developed and the formation of sandwich compression was analyzed. The yield stress of the wood was influenced by the thermal effect and plasticizing effect. In the process of increasing temperature and MC, the yield stress decreased gradually. And the yield stress change rate was 0.29–0.46 MPa in the MC range of 5–10%. The prediction model of wood yield stress was developed by a multiple linear regression analysis. This example demonstrated that coupling distributions of MC and temperature were formed upon heating at 180℃, which led to a gradient distribution of the glass transition temperature and yield stress inside the wood. This phenomenon resulted in the sandwich softening behavior under the coupling of moisture and heat, which was the key formation mechanism of sandwich compressed wood. [Display omitted] • The wood exhibited sandwich softening behavior via the coupling of moisture and heat. • The wood softening was characterized by yield stress and glass transition temperature. • Sandwich softened wood was made into sandwich compressed wood under mechanical force. [ABSTRACT FROM AUTHOR]

This study examined the feasibility of acoustic stress wave velocity (V) evaluation commonly used to grade wood veneer for predicting the flexural Modulus of Elasticity (MOE) of flattened Moso bamboo. The correlation between MOE and V was low in bamboo compared with Douglas fir wood veneers, due to much lower grain angle deviation in bamboo. Bamboo had 30% lower MOE than Douglas-fir, likely linked to a combined effect of shorter cells and higher average microfibril angle of parenchyma cells in bamboo. Segmenting by density can effectively group flattened bamboo veneers into different MOE grades (R2 = 0.52) but assaying for both density and V gives more reliable prediction of apparent MOE (R2 = 0.86). [Display omitted] • Improved understanding of stress wave behaviour in bamboo and wood. • Wave velocity detects ∼35% of stiffness and ∼50% density variation. • Wave velocity reduced in bamboo by short parenchyma cells. • Grading flattened bamboo veneers using density and stress wave measurements. [ABSTRACT FROM AUTHOR]

Decorative veneer, rotary cut from wood, serving as the outermost layer of decorative plates and is exposed to potential risks of fire hazards and bacterial growth. In this study, following the principle of eco-friendly and cost-effective, the polyamino polyether methylene phosphonate (PAPEMP) and magnesium chloride (MgCl 2) were sequentially impregnated into the veneer, and then the alkaline environment was employed to facilitate the complexation, leading to the formation of cross-linked chains within the porous wood structure. Consequently, the modified wood veneer, endowed with exceptional flame retardancy, smoke suppression, antibacterial properties, and good wettability was successfully achieved. Through optimization in an alkaline environment, the modified decorative veneer exhibits a remarkable increase in limiting oxygen index from 19.7% in the pure veneer to 36.9%, coupled with a significant reduction of 19.38% in total heat release and 65.22% in total smoke release compared to the pure veneer. Additionally, the peak mass loss rate (PLMR) of the modified veneer was 66.41% lower than that of the pure veneer, and the char residue increased to 46.1%, representing a 149.19% improvement over the pure veneer. Compared with pure veneer, the wettability of modified veneer increased by 37.93%. Additionally, the tensile strength parallel to the grain of the modified veneer was enhanced by 22.09% compared to the veneer without NaOH solution treatment, and exhibits strong inhibitory effects on colony reproduction. The developed flame-retardant and antibacterial treatment processes for decorative veneers offer a novel and environmentally friendly method for utilizing precious tree veneers, suitable for a variety of precious woods, and successfully applied to decorative wooden doors and wooden fire-resistant doors. [Display omitted] • The precious wood veneer is modified by an efficient flame-retardant system. • The flame-retardant system is convenient, green and environmentally friendly. • Modified veneer offers excellent flame retardant and antibacterial properties. • Modified veneer exhibits significant wettability and mechanical performance. [ABSTRACT FROM AUTHOR]

In this study, axial compression test and real-time acoustic emission (AE) monitoring were conducted on six groups of wood components with different carbon fiber reinforced polymers (CFRP) winding methods. The effects of different winding layers and angle on the failure mode, mechanical properties, energy absorption performance, and AE parameter evolution of CFRP-reinforced wood components were analyzed. The results show that the reinforcement of CFRP can significantly improve the mechanical properties of wood and suppress the occurrence of brittle failure. As the CFRP winding layers and angle increase, the ultimate bearing capacity of the wood components increased from 112.63 kN to 161.21 kN, and the displacement ductility factor also increased from 1.44 to 1.72. The increase in the CFRP winding layers and angle can significantly improve the stability and energy absorption capacity of CFRP-reinforced wood components during axial compression damage, and the specific energy absorption (SEA) is increased from 41.68 J·g−1 to 75.01 J·g−1. The damage process of CFRP-reinforced wood components can be divided into three stages: elastic, compressive yield, and damage failure, based on the evolution characteristics of AE ringing counts and time-load curves. With the increase of the winding layers and angle, the AE peak frequency gradually transitions from the low-frequency interval (0–80 kHz) to the high-frequency interval (160–240 kHz), and the form of damage changes from large-scale damage to small-scale damage. The AE energy probability density of wood components with different winding modes follows a power-law scale-free distribution. The critical index increases with the increase of the winding layers and angle, indicating that the reinforcement of CFRP is able to limit the development of internal cracks in wood and attenuate the deterioration of the internal structure. The damage evolution model established based on the relationship between the number of AE cumulative events and load can well reflect the damage evolution law of the material in the axial compression process. • Real-time AE monitoring of the axial compression damage process of CFRP-reinforced wood components was performed. • The mechanical and energy absorption properties of CFRP-reinforced wood components were investigated. • The failure mechanism of CFRP-reinforced wood components was revealed by the evolution law of AE parameters. • A damage evolution model based on the number of AE cumulative events and the load relationship was established. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride cement (MOC) has the advantages of no formaldehyde emission, fire resistant and curing at ambient temperature, which make it to be a promising wood adhesive for wood industry. However, the poor permeability of MOC on wood surface and the inherent brittleness of MOC limit its practical application. To solve these problems, citric acid (CA) and polyvinyl alcohol (PVA) fibers were demonstrated to synergistically promote the bulk penetration of MOC in wood surface and enhance the toughness of MOC, which resulted from the pH regulating effect of CA and the toughening effect of PVA fibers and CA. Based on this synergistic method, the compressive strength and toughness of the obtained MOC/CA/PVA adhesive were higher than that of pure MOC adhesive. Moreover, the wet adhesive strength of the MOC/CA/PVA adhesive reached 1.81 MPa, which increased by 33% than pure MOC adhesive. In addition, the wood products bonded by the modified adhesives possessed excellent flexural performance and fire resistance. This modification strategy makes the modified MOC-based wood adhesive have great application potential in wood and building industry. • Magnesium oxychloride cement was modified by citric acid and PVA fibers. • Citric acid and PVA fibers improved the water resistance and strength. • The enhanced mechanism was the chelation of CA and the filling effect. • The modified magnesium oxychloride cement has good adhesive strength. • The wood product bonded by modified adhesives has better flexural strength. [ABSTRACT FROM AUTHOR]

Catalytic degradation via fly ash impregnation (Im) has proven effective in reducing the heat modification (HM) temperature required for wood. To accurately gauge the intensity of HM on wood following Im, the physiomechanical properties of Im-HM treated wood were investigated across various treatment conditions (temperature: 80–140°C, duration: 1–4 h, and fly ash concentration: 2–8%), and compared them to conventional HM (CoHM) wood. Two mathematical methods (time-temperature superposition and cluster analysis) were employed to elucidate the relationships between treatment conditions and resulting properties. Results indicated that Im-HM treated wood exhibited comparable dimensional stability and visual appearance to CoHM wood, while retaining superior mechanical properties. The acid-catalyzed effect of Im-HM demonstrated significant dependence on treatment temperature, duration, and concentration, providing an avenue to regulate catalytic intensity. Employing the time-temperature superposition principle, master curves for weight percentage loss (WPL), modulus of elasticity (MOE) and anti-swelling efficiency (ASE) were constructed under a reference condition (80°C and 2% concentration), covering processing duration up to 20 hours. These master curves facilitated understanding the relationship between temperature, duration and concentration when evaluating catalytic intensity. Cluster analysis, based on the physiomechanical properties of Im-HM and CoHM wood, offered a clear interpretation of HM intensity. Notably, Im-HM treatment at 140°C for 4 hours with an 8% concentration exhibited HM intensity similar to CoHM treatment at 200°C. Through the integration of time-temperature superposition and cluster analysis, this study assesses Im-HM intensity, providing a valuable reference for the industrial application of Im-HM treatment. • The physiomechanical properties were explored under varied fly ash impregnation and heat modification conditions. • Time-temperature superposition principle was applied to establish the master curves for three properties. • Cluster analysis offered a clear interpretation of heat modification intensity after fly ash impregnation. [ABSTRACT FROM AUTHOR]

The inherent moisture absorption and flammability of wood can diminish its practical application value. In this research, a phytic acid-based flame retardant (PM) was synthesized by a hydrothermal method. Iron ions-doped phytic acid-based nanosheets (PM-Fe3+) deposited on wood surface by vacuum impregnation. Subsequently, the wood was hydrophobically modified with octadecylamine (OA), resulting in the successful fabrication of superhydrophobic and flame-retardant composite wood (PM-Fe3+/OA/wood). The influence of various coating components on the wettability, heat, and flame retardancy properties of composite wood was examined through water contact angle (WCA), vertical burning tests (UL-94)， limiting oxygen index (LOI), and a cone calorimetry test. The results indicated that the WCA of PM-Fe3+/OA/wood was 154.9°. The composite wood possessed exceptional contamination resistance and self-cleaning properties due to its superhydrophobic surface. Furthermore, due to the dry surface of PM-Fe3+/OA/wood, it exhibited superior resistance to mold in comparison to natural wood. The combustion test results indicated that PM-Fe3+/OA wood exhibited an extremely short time to self-extinguish, achieving V-0 rating. It had a LOI value of 38.6%. Additionally, in the cone calorimetry test, the peak heat release rate (PHRR) and total heat release (THR) of composite wood were reduced by 56.6% and 52.2%, respectively. In summary, this work provides an attractive strategy for obtaining wood with superhydrophobic and flame-retardant properties, which enhances its practical application value. [Display omitted] • Iron-ion doped phytic-based nanosheets deposited on wood surface by vacuum impregnation. • Superhydrophobic and flame retardant composite coatings were constructed on wood surface. • Superhydrophobic coating exhibited exceptional chemical and environmental durability as well as self-cleaning properties. • Superhydrophobic coating endowed wood with excellent mold resistance. • Composite wood showed excellent flame retardancy in terms of self-extinguishing behavior. [ABSTRACT FROM AUTHOR]

Producing cross-laminated timber (CLT) has opened a new market for the lumber industry in North America, while few hardwood species have been studied in the U.S. for CLT production. Combining hardwood species in mixed hardwood CLT or in hybrid CLT can be a solution to boost the market of the undervalued hardwoods. However, the knowledge gap on bonding hardwoods needs to be filled to provide evidence of feasibility. This study focused on the face bonding properties of the cross laminations made of seven hardwood species and two softwood species from the Great Lakes region using two commercial structural adhesives, the phenol resorcinol adhesive (the Resorcinol) and the melamine urea formaldehyde adhesive (the Melamine). A total of 45 combinations of the selected species were studied for the bonding strength (shear under compression) and the percentage of wood failure. For single species samples, the bond strength was positively related to the specific gravity of wood and the bond strength of hardwoods was 33% and 82% stronger than that of softwoods bonded with the Resorcinol and the Melamine respectively. The mixed hardwoods showed higher bonding strength (the Melamine: 5.45 MPa, the Resorcinol: 5.28 MPa) than mixed softwoods (the Melamine: 2.8 MPa and the Resorcinol: 2.7 MPa). Among the Resorcinol bonded mixed combinations, 54% had a percentage of wood failure less than 80%, while the Melamine bonded had only 4 out of 22 which had a percentage of wood failure less than 80%. The overall bonding strength of the hybrid combinations was 5% weaker than that of the mixed hardwoods. All hybrid combinations bonded with the Melamine met the 80% wood failure criterium, but some bonded with the Resorcinol had a percentage of wood failure less than 80%. Anatomical features, especially pore distribution, played a key role in the bonding performance. However, the Melamine adhesive consistently achieved over 80% wood failure across all pore distribution types. • Stronger bonds correlated with denser wood and less percentage of wood failure in high-density diffuse-porous wood. • Using high-density ring-porous wood in cross-lamination can boost bonding performance. • Ring-porous wood excel in cross-lamination bonding properties over diffuse-porous wood. [ABSTRACT FROM AUTHOR]

The interaction of transversal tension/compression stress with longitudinal shear stress extensively exists in practical timber components. Thus, the investigation of the mechanical properties of wood subjected to such loads is of particular significance. In this paper, forty-eight larch wood specimens were prepared, the configuration of which resulted from a modification of the most sophisticated V-notched shear specimen to consider the normal loading requirement. Experiments were carried out on an MTS uniaxial testing machine responsible for the shear loading. An auxiliary device was designed and equipped to the testing machine to produce constant normal load. Digital Image Correlation (DIC) technique was used to record the full field deformation and the whole failure process. Failure modes, and shear stress-strain curves under different normal stresses were obtained. The applicability of several commonly used orthotropic strength criteria including Hill, Tsai-Hill, Tsai-Wu, Hoffman, van der Put, Norris, and SIA 265 criteria, et al. to predict the combined transversal tension/compression and longitudinal shear failure were systematically assessed according to test data from the experiment as well as existing literature. Results indicated that transversal tension stress promotes shear failure, while compression stress has a suppressive effect on shear failure. The longitudinal shear strengths can be evidently raised by increasing transversal compressive stresses, while tensile stress reduces the longitudinal shear strength. Van der Put and SIA 265 criteria are most suitable to predict the longitudinal shear failure of wood under different normal stresses, and the former produces the least error. In addition, the best applicable normal stress ranges of the examined failure criteria were confirmed. • A novel combined normal-shear loading device was designed to perform biaxial experiments based on a uniaxial testing machine. • The effects of different levels of normal stresses on the shear failure modes, stress-strain curves, et al. were revealed. • The applicability ofcommonly used strength criteria to predict the combinednormal-shear strength behavior was assessed. • Van der Put and SIA 265 criteria are most suitable to predict the longitudinal shear failure of wood under normal stresses. [ABSTRACT FROM AUTHOR]

With the advent of the 5 G era, data transmission is faster, but because the concrete is a natural wave absorber agent, the signal in underground space, building groups and other areas is still poor, and there are few reports on how to improve the electromagnetic transmission performance of concrete in the 5 G frequency band and mechanism analysis. In addressing these issues, this study incorporated 0 wt%, 1 wt%, 2 wt%, and 3 wt% functionalized nanoscale wood fiber (NWF) into ordinary Portland cement (OPC) paste to assess their impact on the compressive strength and electromagnetic transmission performance (ETP). The findings reveal that while NWF reduces the OPC paste compressive strength. However, it exerts a positive influence on the molecular structure, electrostatic force, pore solution, and pore structure. Ultimately, the ETP of OPC paste can be enhanced by 10.3–47.1%. Notably, at 2 wt% NWF content, the ETP is significantly improved (boosted by 33.1%), with an impressive electromagnetic transmission coefficient of 66.8%, while the compressive strength is only reduced by 16.7%. • NWF can greatly improve the ETP of cement paste. • The mechanism of how NWF improves the ETP has been analyzed. • A method for improving the ETP has been proposed. [ABSTRACT FROM AUTHOR]

Currently, three classes of materials are used in deck boards production, i.e., wood, plastics and wood polymer composites. Wood is the best choice being bio-based, biodegradable and displaying better mechanical performance, but the environmental concerns deriving from forest depletion make the identification of a new bio-based solution necessary. In this sense, agglomerated cork is promising, being derived from the bark of the oak, but in its native form is not suitable for decking boards production due to low bending properties. The present work proposes a solution to use agglomerated cork in decking board manufacturing by converting its cellular structure in a consolidated one by hot compression. Design of Experiment was used to optimize consolidated cork mechanical properties as a function of the main manufacturing parameters, i.e., time and temperature. The exposure to high temperatures allows cork cell walls welding by developing adhesive properties, but it also induces a strong degradation of polysaccharides. It was discovered that the manufacturing parameters which maximize both flexural and tensile properties are a 180 °C operating temperature and a 31.5 min holding time. These conditions ensure a bending stiffness 40.9% and a bending strength 107.1% higher than the ASTM D6662 minimum requirements. • Agglomerated cork was consolidated by hot compression for decking boards production. • Mechanical properties were optimized through Design of Experiment. • Bending stiffness and strength of optimized configuration are 40.9% and 107.1% higher than ASTM D6662 minimum requirements. • The optimized configuration ensures the lowest water uptake fundamental for outdoor use. • Consolidated cork proved to be a feasible solution to produce eco-friendlier deck boards. [ABSTRACT FROM AUTHOR]

The aim of this study is to explore the potential of using biomass-ash waste as a secondary raw material for building composites. The waste is generated by a thermal power plant that burns woody biomass and would otherwise be disposed of in landfills. The study investigates the physical and mechanical properties of gypsum-based composites containing different proportions of biomass-ash waste and compares them with the reference and regulatory documents. The study also proposes some possible building applications for the optimal composite and evaluates its performance through simulations. The results indicate that adding up to 25% wood ash can improve the mechanical strength of the composites, exceeding the reference and minimum requirements. The proposed building applications using the new composite reach a reduction in the environmental impact and an improvement in the energy efficiency of the building envelope. [Display omitted] • A new gypsum composite for building applications following circular economy criteria is characterized. • Wooden biomass ash can be incorporated up to 25% in gypsum composites complying with the standards. • Plates for suspended ceiling and plasterboads are designed with lower environmental impact and greater energy efficiency. [ABSTRACT FROM AUTHOR]

To dynamically assess the damage to wood under external loads, in this study, a grid-based time difference of arrival (TDOA) algorithm for acoustic emission source plane localization was proposed. The algorithm, can help determine the damage location. First, Zelkova schneideriana and Pinus sylvestris var.mongolica were selected as test materials, and the acoustic emission (AE) source was simulated by pencil lead breaking (PLB) on the surface of the specimens. The TDOA linear localization method was used to calculate the propagation velocity of the AE signal along the grain direction in the wood. Based on the time difference of the AE signal reaching different sensors in the vertical grain direction, the vertical grain direction was divided into regions, and the regional grid model was established by combining the positions of different AE sources in the grain direction. Subsequently, a grid-based TDOA regional localization method was used to locate the damage source, and the accuracy of the method was determined through error calculations. Subsequently, using the damage sources generated by the three-point bending test, the AE signals generated at different moments before the specimen reached the yield limit were selected, and the AE sources were localized using the established regional grid model. Finally, the location of the AE source was determined to predict the crack growth and the area where the macro-cracks appear. According to the test findings, the relative error in the position of the AE source in the forward texturing direction can be controlled within 2%, and its absolute error is significantly less than the 9.5 mm radius of the test sensor, indicating high positioning accuracy. To a certain extent, crack propagation at the beginning and the fracture position at the end may be accurately located using the TDOA regional grid placement method. Additionally, this method has the capability to illustrate, the evolution and development of damage. • A locally gridded acoustic emission source localization algorithm is proposed. • PLB tests were performed to derive the velocity in the grain direction. • Mesh modeling based on different time differences in signal arrival at the sensor. • For damage source localization, this accuracy was determined by error calculation. • Three-point bending test of the specimen to localize the source of damage. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of superheated steam treatment at different pressures (0.1 MPa, 0.3 MPa, 0.5 MPa, and 0.7 MPa) on the physicochemical properties of surface-compressed (SC) poplar wood. Applying a 20% compression ratio significantly increased the average density of the SC wood, while reducing its surface wettability and roughness. The compressive deformation of SC wood with superheated steam treatment (SHTSC wood) could be permanently fixed under a steam pressure of 0.7 MPa, yielding higher hydrophobic surface properties. Furthermore, the surface color of SHTSC wood resembled that of hardwood commonly used in furniture. The structural changes, such as increased surface density and decreased roughness, had a greater impact on reducing the surface wettability of SC wood than chemical changes. Additionally, superheated steam treatment led to deacetylation of hemicellulose, demethoxylation of lignin, and an increase in the relative crystallinity and crystal width of cellulose, thereby improving the surface properties and dimension stability of SHTSC wood. Overall, this study demonstrated that the combined modification treatment provides a new perspective for enhancing the utilization of fast-growing wood. • The combination of surface compression and superheated steam treatment was conducted for upgrading fast-growing wood. • High superheated steam pressure was able to permanently fix the compressive deformation. • The treated wood showed improved density and dimensional stability. • The surface color of treated wood resembled that of hardwood commonly used in furniture. [ABSTRACT FROM AUTHOR]

Melia dubia is a rapidly expanding tree species in southern India, but its main drawback has been limited use in wood-based panel products until recently. To address this research gap, this study aimed to develop three reinforcement materials for producing Reinforced Laminated Veneer Lumber (RLVL) using Melia dubia. Three types of reinforcement materials, chopped glass fiber mat (CGM), glass fiber mesh (GM), and bamboo mat (BM) were employed in two layers to manufacture RLVL. The investigated parameters included physical, mechanical, and bonding performance. Furthermore, morphological images were analyzed using optical and scanning electron microscopes. The research findings revealed that the highest performance was demonstrated by BM, followed by GM and CGM. These results suggest that all three reinforcements enhanced the mechanical properties and overall performance of RLVL. Arranging the reinforcement layers closer to the surface veneer layer in the assembly resulted in outstanding mechanical properties for RLVL. The performance is superior to solid wood made from the same wood species. The findings indicate that RLVL demonstrated superior mechanical properties to laminated veneer lumber (LVL) and solid wood. The modulus of rupture for LVL reinforced with CGM, GM and BM was 7.27%, 30.91%, and 32.73% greater respectively, than that of unreinforced LVL. The composite LVL reinforced with bamboo and glass matting exhibits potential for successful utilization in outdoor structural applications, including beams, rafters, and purlins. • LVL reinforced with CGM, GM, and BM exhibited excellent modulus of rupture. • RLVL demonstrated superior mechanical properties to LVL and solid wood. • LVL reinforced with GM and BM can successfully utilized in outdoor structural applications. [ABSTRACT FROM AUTHOR]

Laminated veneer lumber (LVL) is an engineering wood product made of veneer through laminated grouping and pressurized gluing, and it can efficiently use fast-growing and small-diameter wood. The existing connection methods for LVL structures are mainly metal fasteners. Compared with metal fasteners, wood dowels have the characteristics of being easy to tear down and recyclable, which has gained increasing attention in recent years. Based on this, the proposal suggested a dowel-type timber joint for connecting LVL members or laminates. Bending tests of wood dowels, dowel bearing tests between wood dowel and LVL, and double-shear tests of dowel-type timber joints were carried out. Several factors were analyzed to explore their influence on the failure mechanism and shear capacity of dowel-type timber joints. These factors include the wood grain direction, the ratio of side laminate thickness to dowel diameter, and the thickness ratio of middle-to-side laminate. Simplified models of dowel-type timber joints under main failure modes were established, and a theoretical equation of shear capacity was proposed based on Johansen's theory. The test results showed that the shear capacity of dowel-type timber joints was comparable to that of dowel-type steel joints under the same dowel diameter. The wood grain direction of laminates had little effect on the failure modes of dowel-type timber joints, but it could affect the shear capacity of joints by affecting the dowel-bearing capacity. The parameter analysis showed that the ratio of side laminate thickness to dowel diameter had an important effect on the failure modes of dowel-type timber joints. The failure modes of joints approached shear failure as the ratio increased. The modified theoretical equation could well predict the shear capacity of dowel-type timber joints under plastic hinge failure and shear failure. • A kind of dowel-type timber joint connecting LVL members or laminates was proposed. • Bending tests of wood dowels, dowel bearing tests between wood dowel and LVL, and double-shear tests of dowel-type timber joints were carried out. • Important factors were analyzed to explore the influence on the failure mechanism and shear capacity of dowel-type timber joints. • A theoretical equation of shear capacity of dowel-type timber joints was proposed based on Johansen's theory. [ABSTRACT FROM AUTHOR]

Wood scrimber (WS) is a high-performance wood-based material that can substitute for high-quality wood as a renewable building material. However, when used outdoors, WS is prone to mildew, which seriously affects its surface performance and causes microbial infiltration. Due to the poor permeability of WS, it is difficult to render it mildew-resistant. In this work, we report a method to achieve the deep penetration of an anti-mildew agent into WS by using a punctated microcracked structure. Compared with the traditional impregnated WS samples (MDI@IPBC@WS), the effectiveness of punctate microcracked WS (MDI@IPBC@P-WS) for Aspergillus niger V. Tiegh and Botryodiplodia theobromae Pat were 25% and 75% higher, respectively. Additionally, there is a notable improvement in the mechanical characteristics and dimensional stability of MDI@IPBC@P-WS. Compared with WS, the thickness swelling rate (TSR) and width swelling rate (WSR) of MDI@IPBC@P-WS decreased by 51% and 25%, respectively, and the modulus of rupture (MOR) and short-beam strength (SS) increased by 11.9% and 12.1%, respectively. The excellent performance of MDI@IPBC@P-WS may allow it to be widely used in outdoor landscaping and building materials, thus providing a new strategy for the high-value-added utilization of fast-growing wood. In addition, this minimally invasive method is simple and green and is expected to achieve large-scale and continuous production. [Display omitted] • Anti-mildew property of wood scrimber increases 75% via structuring microcracks. • The dimensional stability of the mildew-resistant wood scrimber is improved by 51%. • The bending strength of the mildew-resistant wood scrimber was increased by 31.2%. • The treatment method was universal and showed excellent mildew control for other species wood scrimber. [ABSTRACT FROM AUTHOR]

An experimental program was conducted to clarify the wood swelling effect on the shear strength and failure modes of adhesively bonded timber-concrete composite (TCC) joints. A total of 150 TCC joints were fabricated and cured in the condition of 20 °C & 55% relative humidity (RH) for one month, then the joints were divided into three groups (50 each group) and treated at 20 °C and 55%, 75%, and 95%RH, respectively. After about 30-, 100-, 200-, 300-, and 390-day treatment, ten samples from each group were tested to determine their shear strength and failure modes. It was found that an increase in moisture content (e.g., by 10.8%) caused a reduction of shear bond strength (e.g., by 25%). Concrete failure was found to be the dominant failure mode for all tested joints. Finite element (FE) analyses were performed to facilitate understanding of the underlying mechanisms of wood swelling effects. When the moisture content of wood increased by 10.8%, the FE analyses showed that the wood swelling resulted in significant internal stresses and concrete tensile damage at the wood/concrete bonding interface, which was the main reason for the reduction of the shear bond strength. In addition, the effects of essential factors, such as material properties of adherents, orientation of wood components relative to the bonding surface, and bonding width perpendicular to the grain direction of wood, on the moisture-induced stresses were studied. Concrete grades hardly had influence. For the bonding process of TCC structure in practice, a smaller orientation angle (i.e., the angle between the radial direction and the bonding surface) is recommended to avoid moisture-induced damage in wood and concrete at their interface. In other words, the surface of a Glulam or CLT product designed for bonding should be as close as possible to R-L planes of the constituent wood blocks and avoid T-L planes. Furthermore, a larger bonding width resulted in higher moisture-induced stresses. • Wood swelling effect on shear strength and failure mode of adhesively-bonded timber-concrete composite (TCC) was studied. • Effect of environmental conditions on the failure of TCC joints was evaluated. • FE model was performed to show the underlying mechanisms of wood swelling effect. [ABSTRACT FROM AUTHOR]

Fast-growing wood species are unsuitable for direct use in load-bearing structures due to their loose fiber structure, low mechanical strength, and inadequate combustion performance. Traditional impregnation using low-molecular-weight resin may enhance certain characteristics but also poses environmental pollution risks. This study explores an alternative approach: subjecting Chinese fir lumbers to thermal treatment, impregnation with an inorganic solution, compression, and utilization as exposed side laminas for glulam beams. The fire performance of full-scale beams was evaluated under three-side fire exposure conditions. Results revealed that addressing the mechanical deficiencies of thermally treated wood could be achieved through 2.0 mol/L inorganic solution impregnation combined with a 20% compression ratio. The modifier weight percent gains in specimens after thermal treatment increased by 24.8% under identical conditions. Composite modification notably enhanced both mechanical and combustion properties, manifesting promising flame-retardant effects. Building upon these findings, fire-resistant laminas were created and applied to the tensile zone of the glulam beam to investigate residual bearing capacity post three-side fire exposure. After 60 min, the modified laminas-containing beam in the fire-exposed tension zone showed a 31.4% increase in residual bearing capacity over the untreated beam. This study underscores that the combined modification methods are not only cost-effective and environmentally friendly but also establish a vital theoretical foundation for safeguarding the structural safety of rapidly cultivated fast-growing wood in fire scenarios. • A modification method to improve wood's mechanical and combustion performance. • Containing modified laminas on fire-side of glulam beams reduces charring rate. • An exact formula for calculating glulam beams' residual bearing capacity post-fire. [ABSTRACT FROM AUTHOR]

Using engineered wood products (EWPs) in the building technologies is very crucial in terms of sustainable approaches. They provide; low weight, high structural stiffness, carbon storage capacity and easy erection on site. EWPs are composite materials that are influenced by a variety of factors that play a critical role in their formation. The chemical ingredients of the wood, the curing process of the adhesive, the type of wood, the relationship between the adhesive and the wood species, the curing temperature, the geometric configuration of the lamellae, etc. can all be included under the heading of these factors. In contrary with massive wood, to obtain EWPs different types of adhesives can be used. Therefore adhesive type and its application method affects the quality of wooden structural element. Choosing the appropriate adhesive is one of the steps to be taken to obtain the structurally correct product. Based on this approach, it was decided to investigate the adhesion performance of different adhesive types. This paper aims to present the best bonding method among the melamine urea formaldehyde (MUF) and epoxy adhesives by considering the fiber directions of the wood and the type of adhesive according to the load. One of the aims of this study is to investigate the effect of changing the fiber direction of wood on adhesion performance, taking into account the current gap in the literature. Pull-off tests were conducted to assess the bonding performance of different types of adhesive in wood samples with varying fiber direction. The wood samples were bonded to the wood surface with varying grain directions. During the pull-off tests, ruptures in the glue line of the test samples were commonly observed. The results have shown that in cylindrical samples bonded with epoxy, the highest bonding strength values were observed in scenarios where the wood fibers were oriented parallel to the load direction and perpendicular to the ground plane. Similarly, for wood samples used as the bonding surface, the highest bonding strength values were achieved when the wood fibers were oriented parallel to the load direction and perpendicular to the surface plane. On the other hand, the highest value in pull-off test setups was found with melamine urea formaldehyde adhesive; commonly used in laminated timber, between the wood samples with grains perpendicular to the load direction and the wood adherence surfaces with a parallel grain direction. In summary, the highest strength value was obtained from the test setup in which epoxy was used as the adhesive and both the wood specimens and the wood bonding surface had fiber directions parallel to the load direction. • The fiber directions of wood in terms of bonding performance are evaluated. • Epoxy provides stronger adhesion than MUF in EWP's technology. • The parallel grain direction of wood exhibits the strongest bonding performance relative to the applied load. • The perpendicular direction of the wood fibres to the applied load is the most critical point in terms of strength. [ABSTRACT FROM AUTHOR]

The maintenance of historic wooden structures requires the assessment of the timber elements that compose them. The accurate knowledge of their mechanical performance is a fundamental aspect to guarantee conservation, safety, and usability. In this work, the assessment of the mechanical properties of timber was done by visual and machine strength grading. The visual grading rule developed for new wooden products was applied, as well as that established by the Italian standard for historic load-bearing structures. Machine grading was also performed by simulating the procedures applicable to the dismantled or in situ elements. The strength and stiffness values expected according to the different strength grading procedures were compared with the values obtained from destructive tests. As a result of visual grading, the modulus of elasticity was in line with the provisions of the standardization, while the characteristic strength was lower. With machine grading the yields were lower, but the characteristic strength values of the classes were respected, especially if combined with a visual inspection rejecting decayed or damaged pieces. The modulus of elasticity, however, was higher than that of the class, thus being underestimated. • Prediction of the mechanical properties of historic load-bearing wooden structures is crucial for their conservation. • Visual and machine strength grading were applied on dismantled timber and verified through destructive tests. • Bending strength was lower than expected by applying the visual grading rules, the modulus of elasticity was in line. • The machine grading led to lower yields, but the characteristic strength of the classes were respected. [ABSTRACT FROM AUTHOR]

• With regard to the high quality standards for adhesive bonding, GiR have proven to be very robust. • Only voids had a great influence on the performance; dirt , oil , and rust had little to no. • The influence of the defect is relatively independent from that of the adhesive of wood. • GiR in beech LVL achieve higher load capacities compared to joints made of spruce GLT. • An Analysis of Variance (ANOVA) showed that the effect of most defects is not significant. Glued-in rods (GiR), which consist of rods glued into structural elements of wood, or engineered wood products, share the manufacturing quality concerns associated to adhesively bonded joints in general. Because of the difficulties associated with the bonding process, it is often argued within the timber engineering community that under the specific conditions prevailing in construction sites, it is not possible to meet the high-quality requirements for bonded joints typically encountered in other industries. The present study presents experimental evidence gathered on 240 individual probes in which the effect of several different types of defects (excessive wood moisture content, wood chips not removed from the borehole, simulated air inclusions by mixing polystyrene spheres, oil contaminated rods, and corroded rod) was investigated with threaded rods glued into beech spruce glued laminated timber (GLT) and beech laminated veneer lumber (LVL) using four adhesives (including 2K-epoxies and a 2K-polyurethane). Results were analysed by means of an analysis of variance (ANOVA). The findings showed that glued-in rods represent a relatively robust class of adhesively bonded joints, as the majority of defects types could not be distinguished on statistical ground from the reference sets, with the notable exception of air voids leading to a significant decrease of joint capacity. [ABSTRACT FROM AUTHOR]

• Heat treatment led to structural changes in wood cell wall compounds. • Structural changes didn't affect the elastic modulus but decreased the creep modulus at treating temperature higher than 160 °C. • At treating temperature of 160 °C, an improved creep performance. • At relative humidity of 90%, heat treatment led to an improvement in creep behavior. In this study, wood was heat treated at temperatures of 160, 175 and 190 °C and creep behavior of modified wood at various moisture contents was assessed. Fourier-transform infrared spectroscopy (FTIR) was conducted to find a relation between creep behavior and structural changes, aiming to develop their applications for construction purposes. FTIR results showed fundamental structural changes: removal of extractives, hemicelluloses and amorphous parts of cellulose and partial degradation of lignin. Creep results showed that unlike elastic short-term modulus, creep modulus decreased at treating temperature higher than 160 °C. Treated samples at 160 °C had an improved creep performance in moist conditions, attributable to lower degradation of cell wall components and to the lower hygroscopicity. [ABSTRACT FROM AUTHOR]

• Two kinds of silane coupling agents (r-aminopropyl triethoxy silane, KH550; and trimethoxy vinyl silane, A171) and dicumyl peroxide were used to bond the wood fiber/high-density polyethylene (WF/HDPE) composite and wood veneer. • Samples treated with A171 had higher bonding strength than those treated with KH550. • The greater the volume of wood fiber in the WF/HDPE, the poorer the bonding strength of the veneer and the lower its water resistance. Because of the smooth, dense, and nonpolar surface of wood-plastic composites (WPCs), it is challenging to form an efficient bonding interface between the WPC and the material of the wood veneer by using traditional adhesives. In this study, two kinds of silane coupling agents (r-aminopropyl triethoxy silane, production number KH550; and trimethoxy vinyl silane, production number A171) and dicumyl peroxide were used to improve the bond between the wood fiber/high-density polyethylene (WF/HDPE) composite and the wood veneer. The attenuated total reflection-Fourier transform infrared spectroscopy curve shows that the two kinds of silane coupling agents were grafted to the surface of the wood veneer, and the contact angle between distilled water and the veneer surface increased from 46° to greater than 120° after treatment. The bonding strength between the treated veneer and the WF/HDPE composite was significantly enhanced, and samples treated with A171 had higher bonding strength than those treated with KH550. The greater the volume of wood fiber in the WF/HDPE, the poorer the bonding strength of the veneer and the lower its water resistance. Images from a scanning electron microscope show that the silane coupling agent A171 can induce a denser interface between the wood veneer and the WF/HDPE composite. [ABSTRACT FROM AUTHOR]

• Mode I fracture characterization of Pinus pinaster Ait. wood was analysed. • The influence of temperature on fracture toughness was studied considering 9 values. • Non-negligible influence of toughness was observed for temperatures exceeding 90 °C. • Cohesive laws were determined to mimic the observed results for tested temperatures. A numerical and experimental study was performed to evaluate the critical strain energy release rate of wood under mode I loading (G Ic), in the range of 30 °C and 110 °C. Pinus pinaster Ait. was employed as testing material, using the double cantilever beam (DCB) test, promoting fracture in the RL fracture system. The determination of Resistance -curves was accomplished using an equivalent crack length method, which does not require crack length measurement in the course of the experimental test. This aspect was found crucial since wood develops a non-negligible fracture process zone (FPZ) ahead of the crack tip, and the experiments required the use of a climate chamber with limited dimensions for visual access. It was observed that the critical energy release rate is affected by temperature within the referred range. Cohesive laws were also determined to replicate the experimental response as a function of the tested temperatures. [ABSTRACT FROM AUTHOR]

• Adhesive free engineered wood products have been manufactured. • Multi-layer timber beams assembled using compressed wood dowels have been tested. • Push-out shear timber joints using compressed wood dowels have been tested under monotonic and cyclic loadings. • Strength and stiffness characteristics of multi-layer beams have been experimentally assessed. • Strength, stiffness and ductility characteristics as well as the cumulative energy dissipation capacity have been assessed. This paper presents an experimental investigation on a novel adhesive free engineered Wood Products (AFEWPs) as an alternative to the conventional glued EWPs which have a high degree of petrochemicals. The research outcomes demonstrate the feasibility of using compressed wood dowels (CWD) as a joint element, to connect timber laminates and members as well as to substitute for adhesives and metallic fasteners. The paper describes the production of thermo-mechanically compressed wood dowels as well as the manufacturing of the dowelled timber specimens. The strength and stiffness properties of CWD are characterized based on three-point bending tests and compared to the values obtained from uncompressed wood specimens. After that, the paper discusses the relative mechanical performances of three-layer dowelled oak beams subjected to four-point bending, in comparison to their conventional glued counterparts. Finally, the paper shows results obtained from double shear push-out tests under both monotonic and cyclic loadings, using two wood species, namely spruce and oak. The obtained results show clearly the potential of thermo-mechanically compressed wood dowel, as a joint fastener, for load bearing capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wood veneers can be used to manufacture corrugated cores of sandwich panels. • Geometric imperfections of the corrugated core reduce its mechanical properties. • Cracks and wood defects will not significantly reduce the mechanical properties of the panels. • The density of panels with a corrugated core is three times lower than solid panels. The environmental issue in engineering approaches is critical due to the requirements of the circular economy. The main emphasis in this work was the experimental and numerical investigation method of wooden sandwich structures' bending characteristics with the corrugated core. It included the effect of natural, randomized gaps in veneer. In addition, the influence of the re-bending of the damaged beam on its mechanical properties was also investigated. The results show that beams are an excellent construction material. The modulus of elasticity of the beams, till failure, ranged from 1580 to 3247 MPa, and the bending strength from 3.3 MPa to 7.9 MPa. In the second bending test, these values decreased after revealing new cracks in the core. It has been shown that the greater the share of gaps, the lower the modulus of elasticity of the beams, the lower the strength, and the lower the value of the destructive force of the beam. Numerical calculations showed that the virtual beam model without imperfections and gaps was characterized by a maximum force of 11.5 % higher than the best beam with imperfections and gaps. The prepared numerical model correctly determined the damage in the core and confirmed its applicability in engineering practice. [ABSTRACT FROM AUTHOR]

• Flame spread and combustion trace on typical decorative wood boards were studied. • Six typical decorative wood boards were tested. • Effect of ambient temperature and wind speed was studied. • Flame spread distance, cracks, flame spread rate were analyzed. • Fourier infrared spectra, SEM microstructure, EDS spectra were analyzed. Decorative wood boards are common combustible materials and have been utilized in lots of buildings, which could bring serious property loss and casualties due to fires. In order to analyze fire hazard of decorative wood boards, horizontal flame spread characteristics and combustion traces were studied on six typical decorative wood boards though the tunnel furnace test in this paper. It was found that the flame spread distance of all the samples were in power function with time. With the increase of ambient temperature and ambient wind speed, the combustion was more intense, the crack length increased, the flame spread distance, and the flame spread rate (V) all increased, the cracks got wider, the micro appearance damage and the degree of carbonization got more serious. Among them, the relationship between V and the initial temperature difference (T v -T i) between solid pyrolysis temperature and the ambient temperature could be expressed as V ∼(T v -T i) θ and the exponent of the power law θ was −6.24 for the decorative wood boards; the relationship between V and the ambient wind speed (U ∞) could be expressed as V ∼ U ∞ δ and δ was 9.0 for the decorative wood boards. In addition, the change rules of C, P and S elements on the combustion residues were similar, which were opposite to the change rule of O. [ABSTRACT FROM AUTHOR]

• A stable EDTA-TA synergistic system was constructed to enhance MOC composites. • EDTA can effectively aggregate 5-phase crystals. • The effect of the synergistic system on the crystallisation of hydration products was investigated. • The modified MOC composites have good water resistance and compressive strength. • MOC composites have excellent flame retardant properties and can be used in the wood industry. The high CO 2 emissions and instability of silicate cement binders during production and use have encouraged the development of low-carbon materials. In this study, an environmentally friendly and flame-retardant building material was produced from magnesium oxychloride cement (MOC) and wood. In practice, the considerable microcracking that forms during the hardening process makes MOC materials very sensitive to water, which limits their further use. Inspired by the predation of crabs, a simple and effective method was proposed to obtain better water resistance and mechanical strength of MOC composite by co-modifying with ethylenediaminetetraacetic acid (EDTA) or disodium ethylenediaminetetraacetic acid (EDTA-Na) in conjunction with tartaric acid. The four –COOH of EDTA and EDTA-Na coordinated well with the 5-phase structure and tightly aggregated the 5-phase crystals, effectively reducing the formation of microcracks. The synergistic effect between EDTA/EDTA-Na and tartaric acid prevented the disruption of 5-phase crystal structures by water molecules, thus improving the water resistance of the MOC composite. The softening coefficients of the MOC composite modified by EDTA and EDTA-Na in cooperation with tartaric acid after soaking for seven days were 0.97 and 0.98, respectively, which is significantly higher than that of the MOC composite modified by tartaric acid alone (0.54). At the same time, the co-modified MOC composite can be utilised as an inorganic adhesive for plywood, and the wet strength of plywood modified with EDTA in cooperation with tartaric acid being 25% higher than that of the unmodified MOC composite. In addition, the resulting composites showed great potential for application in low-carbon building materials, which can help alleviate the environmental impact of construction industries. [ABSTRACT FROM AUTHOR]

• Recycling waste wood propels low-carbon, eco-friendly civil engineering. • Innovative algorithm blend ensures precise composite mix ratio optimization. • NaOH and CH 3 COOH treatments boost wood fiber-cement bond strength. • Biomass composites deliver enhanced flexural strength and carbon sequestration. Forest ecosystems play a significant role in mitigating global warming, primarily because wood is recognized as a crucial natural material for capturing carbon. However, the increasing global demand for wood conflicts with the idea of sustainable carbon capture, emphasizing the importance of recycling waste wood and utilizing it in multiple ways. Despite the potential of wood fibers to strengthen composites, the complexity of their preparation and their natural sugar content limit their applications in recycling waste wood. This study combines the Random Forest and NSGA II algorithms for comprehensive multi-objective optimization, focusing on enhancing the strength, resilience, and carbon capture capabilities of composites. In-depth microstructural analyses, along with elemental mapping, clarify how wood fibers contribute to toughening and resistance to cracking, affirming their vital role in improving the mechanical properties of composites. The study determined the optimal mixing ratio and mechanism of action of NaOH and CH 3 COOH treatments. The Pareto solution set derived from the algorithm aids intricate multi-objective balance analyses. Notably, discrepancies between experimental and optimized values remain minimal, and were recorded at 1.03%, 0.85%, 1.76%, and 2.31%, respectively, thus reinforcing model precision and trustworthiness. Cementitious wood fiber composites' merits set the stage for sustainable product innovations, transitioning theoretical insights into eco-conscious practical applications. [ABSTRACT FROM AUTHOR]

• Thermo-migration of water in wood investigated by in-situ micro-CT imaging. • An original setup was conceived to maintain the temperature gap during CT scanning. • The analysed scans show the dynamics of moisture migration from hot to cold sides. • Above the FSP point, liquid water appears close to the cold side as localized spots. • Simulations prove that the vapor density gradient is the relevant driving force. Wood used as a building material is exposed to non-isothermal and unsteady state conditions involving coupled heat and mass transfer within the porous media. These exchanges contribute to the regulation of relative humidity in a passive way and influence the energy performance of buildings. In order to characterize the importance of the hygrothermal behaviour of softwoods in this context, an experimental setup was developed to access to moisture fluxes and/or moisture content profiles in the presence of a known temperature difference imposed on both sides of the wood sample. This original setup was conceived to maintain the temperature gap during micro-tomography acquisition. Image processing allows the moisture content profiles to be obtained over time after changes of the thermal gradient. The simulation using a computational model of coupled heat and mass transfer confirmed that the gradient of vapor density is a relevant unique, "synthetic", driving force to account for moisture migration in non-isothermal conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • FTIR indicated the formation of the phytic acid-based hybrid complexes. • The bonding strength of phytic acid treated wood improved obviously. Heat-treated wood is widely used in outdoors due to its good dimensional stability and biological durability, while the reduced surface hydrophilicity negatively affects its bonding performance with water-soluble adhesives. In this work, a convenient surface modification strategy was prepared on heat-treated wood by surface modification with phytic acid or phytic acid combined with Fe3+ to improve its interfacial bonding properties. Results showed that the phytic acid and phytic acid-Fe3+ chelate are distributed both in the cell cavity and cell wall, and phytic acid surface coating is smooth while phytic acid-Fe3+ seemed layer-by-layer. These coatings bring a large number of hydroxyl groups to improve the surface wettability of heat-treated wood. Therefore, the water contact angle of both phytic acid treated wood and phytic acid-Fe3+ treated wood at 60 s is smaller than that on control wood. The water contact angle in the earlywood of phytic acid treated wood even reaches 0°. The average penetration and effective penetration of phenol formaldehyde adhesive into heat-treated wood also increase after treatment. On average, the average penetration and effective penetration value of phytic acid treated wood increased from 870 to 997 μm, and 35 to 62 μm, respectively. The average penetration value of phytic acid-Fe3+ treated wood is decreased due to the accumulation of chelates. But its effective penetration value is more than twice that of heat-treated wood. The digital image correlation results that the tensile strength of phytic acid treated wood is much higher than that of heat-treated wood. The shear strain of phytic acid treated wood is distributed more homogeneously. However, the maximum tensile stress of phytic acid-Fe3+ treated wood is poor due to the glueline being too thick to closely connect with wood. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sustainable high-performance bamboo/wood composites (SHBWC) are introduced. • The relationship between global forest area and Roundwood production is analyzed. • The mechanical properties uncertainties of SHBWC are compared with Merbau. • Suggestions for the application of SHBWC and effective reinforced methods are given. • Mechanical performance of SHBWC is analyzed from microscopic characteristics. Sustainable building materials play a vital role in achieving carbon peaking and carbon neutrality goals. Comprehensive knowledge is required to fully understand the development status of sustainable building materials, particularly those made from bamboo or wood fiber, and their advantages in terms of mechanical performance and uncertainties compared to natural wood. The development status of sustainable high-performance bamboo/wood composites (SHBWC) is summarized, and a comparative analysis is conducted on the physical and mechanical performance as well as uncertainties of typical SHBWC compared to natural Merbau, which has extreme density. The findings indicate that the high demand for roundwood is exerting pressure on forest resources, leading to a certain extent of scarcity. Among the various SHBWC, bamboo scrimber (including BSM and BSS), wood scrimber (WS), and laminate bamboo lumber (LBL) are identified as most commonly used. These materials have varying densities, with BSM, BSS, WS, LBL, and Merbau following a descending order. BSS material demonstrates superior tensile and bending strength, measuring at 255.47 MPa and 233.12 MPa, respectively, with a modulus of 25.23 GPa, surpassing other materials. SHBWC show enhanced mechanical properties, uncertainties, dense microscopic characteristics, and a shorter sustainable supply cycle than natural hardwood. However, the mechanical performance of the SHBWC tested in this study could be further improved by reducing gaps in their microstructures. Overall, SHBWC offer a viable alternative to natural high-quality wood in construction applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recycling decontaminated CCA treated wood and general timber waste into a wood geopolymer cement (WGC) composites. • The WGC with the decontaminated wood chips showed higher mechanical properties than both the samples with CCA-treated and non-CCA-treated wood chips. • The compressive strength and MOE decreased as the wood content increased, while the MOR increased with the wood content peaking at WC/B ratio of 0.25. • The WGC with WC/B ratio of 0.1 to 0.25 meets the minimum requirement for making load bearing cinderblocks, while all the samples satisfy the minimum requirement for non-load bearing cinder blocks. • The compressive strength of the WGC generally showed a higher value when compared to similar purpose wood-Portland cement composites. Addressing critical societal challenges, such as climate change, resource depletion, and environmental protection, requires sustainable management of resources. This study reports on the results of an experimental program using waste wood, including chromium copper arsenic (CCA) treated wood, to produce ambiently cured geopolymer cement bonded wood composites (WGC), and the results are very encouraging. The composite exhibited a reasonable compressive strength, which ranged between 7 and 27 MPa inversely corresponding to the amount of wood per binder ratio ranging between 0.1 and 0.4, conferring it the possibility of being used as a building material. The compressive strength of the composite with 40% wood chips showed the lowest compressive strength with values of 9.79, 7.29, and 7.92 MPa for decontaminated, CCA-treated, and non-CCA-treated wood chips, respectively. The results indicated that for all the wood per binder ratios, the use of decontaminated wood chips significantly improves the compressive, flexural, and specific strength of the composites, as well as their ductility, compared to non-decontaminated CCA-treated and non-CCA-treated wood chips. This paves the way for using wood waste in sustainability oriented product development and manufacturing. [ABSTRACT FROM AUTHOR]

• Sine frequency sweep finds the wood's resonant frequency range. • The resonance frequencies of wood are in the range of 30–50 kHz and 150–170 kHz. • The holes hinder the frequency energy and wave in the resonance frequency range. • The frequency energy decay rate raises with the holes' diameter and number rises. • Detecting holes by the frequency energy decay rate in the resonance frequency range. In order to detect the hole defect in the wood, the intrinsic frequency of wood is investigated by frequency sweeping and combining with pencil-lead break (PLB) tests to examine the influence of the hole defect on the intrinsic frequency to obtain the significant change index for non-destructive detection of the holes. Initially, the sweeping frequency test is conducted in the range of 10–180 kHz on two different sizes of Zelkova schneideriana and Pinus sylvestris var. mongholica specimens, followed by the signal's frequency domain analysis to determine the natural frequency and its range. Then, holes with diameters of 5, 10, and 20 mm are drilled on the Zelkova schneideriana specimens to explore the impact of hole diameter on the natural frequency using PLB and frequency sweeping. Finally, 1, 3, and 5 holes of 8 mm are drilled to investigate the influence of hole number on natural frequency. The results showed that the natural frequency of wood falls within two frequency ranges of 30–50 kHz and 150–180 kHz. In addition, the hole hinders the AE signal's propagation. The energy decay rate in the two natural frequency ranges increases as the diameter and number of holes rise. In addition to the traditional method for calculating signal propagation speeds, this study proposes effective measures for detecting holes in wood. [ABSTRACT FROM AUTHOR]

• Wood fiber produced with pine waste was used to reinforced AAC. • Detailed comparison between WFAC and performances of PFAC was conducted. • The effect of fiber content in the production was tested. • Wood fiber had a positive impact on the mechanical strengths of AAC, but slightly increased the thermal conductivity. Using fiber produced with wood waste into AAC could reduce the negative impacts on environment and improve the mechanical property of AAC. To obtain a better understanding of wood fiber produced by pine waste used in autoclaved aerated concrete (AAC), a comparative study between performances of wood fiber reinforced AAC (WFAC) and performances of polyester fiber reinforced AAC (PFAC) was conducted. Fluidity of slurry and swollen height of forming mixture were measured during preparation. The influences of fiber content on the physical properties and mechanical properties of products were systematically investigated, together with the SEM investigation. In the most case, the effect of adding wood fiber into AAC was better than that of polyester fiber. Along with the increase of wood fiber content, the fluidity, swollen height and porosity decreased, while the volume density and thermal conductivity slightly increased. The mechanical property was significantly enhanced by wood fiber, particularly the flexural strength. Moreover, SEM results revealed the reinforcing mechanism of wood fiber was a physical interaction. [ABSTRACT FROM AUTHOR]

• Each studied wood species presents a specific acoustic activity in terms of emissivity and energy. • The acoustic activity is related to the degree of heterogeneity of the species. • The more the species is heterogeneous, the more the acoustic signatures are specific. • The more the species is heterogeneous, the more the signals statistical classification is effective. The use of wood in civil engineering structures, such as timber bridges, has been increasing in recent years. Unfortunately, our knowledge of their behaviour towards sustainability problems is far from complete and it is necessary to develop monitoring techniques like acoustic Emission (AE) that allow early identification of pathologies. This study focuses on the analysis of the influence of wood species on the acoustic response under bending loading. The results of this experimental study show a correlation between AE signal features and certain failure mechanisms but also that these acoustic signatures are different for each timber species. [ABSTRACT FROM AUTHOR]

• Wood species identification is crucial for a proper evaluation of timber members. • Semi-destructive test provide information regarding possible aging effects. • The effect of ageing (damage of cell wall) lead to a reduction of tensile strength. • In-situ test information should be crossed with wood species information. A proper assessment of the properties of timber members is dependent upon the capacity for acquiring sufficient information onsite. A large part of this depends on the ability to identify wood species which is consequently used for selecting and applying a suitable visual strength grading standard. However, given the wide variability associated with the mechanical properties, normally above 20%, and the possible ageing effects due to load and moisture history, visual grade information should be complemented by information from onsite tests. This paper presents the results of a methodology for assessing old timber members where all information collected from wood identification and semi-destructive testing (wood coring and tensile tests) are combined and analysed. The results stress the importance that the combination of information from different sources can provide in terms of a safer and more reliable assessment of timber members in service. [ABSTRACT FROM AUTHOR]