Wood Slabs Research Articles

Green and sustainable fabrication of DES-pretreated high-strength densified wood

Wood is a sustainable, benign, and high-performing green structural material readily available in nature that can be used to replace structural materials. However, insufficient mechanical performance (compared to metals and plastic), moisture sensitivity, and susceptibility to microorganism attack make it challenging to use wood as it is for advanced engineering applications. We here present an efficient approach to fabricating densified wood with minimal time and waste generation, demonstrating high mechanical strength, and decreased water penetration on the surface. Wood slabs were treated with deep eutectic solvents (DESs) to solubilize the lignin, followed by in-situ regeneration of dissolved lignin in the wood. Then, the slabs were densified with heat and pressure, turning the wood into a functionalized densified material. Lignin regeneration and morphological changes were observed via two-photon microscopy and Scanning Electron Microscopy (SEM), respectively. The final product is less susceptible to water absorption on the surface and has enhanced flexural strength (> 50% higher), surface hardness (100% increased), and minimal set recovery compared to natural wood. The improved mechanical performance is due to regenerated lignin which acts as a glue and fills spaces present within the interconnected cellulose network inside the wood, forming a highly dense composite during densification. Such enhancement in the properties of DES-densified wood composite makes it a favorable candidate for advanced structural and engineering applications.

Odourless vegetable oils as insect pest repellents for short-term protection of various food packaging materials

The repellent activity of two odourless vegetable oils (sweet almond—SAO and soybean—SO) applied on filter paper and four types of food packaging materials (polyethylene film, plastic gunnysacks, cardboard, and wood) was tested against three species of stored product pests (Sitophilus granarius, Tribolium castaneum, and Oryzaephilus surinamensis). The repellence of three doses was evaluated after 24 h, and after 7, 14, 21, and 28 days. Both oils exhibited a repellent effect when applied to filter paper, but this effect decreased with time and concentration. The most susceptible species was T. castaneum. The maximum repellence was 84% and 76% for SO and SAO, respectively. On packaging materials, the repellent effect diminished after a certain period of time, ranging from 7 to 28 days. Subsequently, the oils even became attractive. Generally, the repellent effects of both SO and SAO were higher on cardboard and wood slab than on polyethylene film and plastic gunnysacks. As such, in the case of SO, the repellence against T. castaneum was 88% 24 h after application on cardboard, whilst 68% on plastic bag. This work demonstrated the repellent potential of vegetable oils in the short term for the protection of packaged food against stored product pests.

Dynamic response of a homogeneous hygrothermoelastic slab sandwiched between elastic half-spaces

In the current study, the authors discuss a homogeneous hygrothermoelastic slab of thickness 2h sandwiched between two similar elastic half-spaces. The hygrothermoelastic slab is subjected to a mechanical source of constant magnitude. The source is applied along the interface of the slab and upper elastic half-space. The analytical expressions of the components of displacement, stresses, moisture concentration, and temperature field are obtained by the normal mode analysis technique. The analytical results are used to solve the problem numerically by taking a wood slab as a porous material. The graphical results elaborate the effect of the thickness of a slab on the physical quantities. The problem of hygrothermoelastic layers sandwiched between elastic half-spaces is a novel idea, which finds its applications in various engineering models. The results found are interesting in the context of the problem. It is observed that the thickness of a hygrothermoelastic slab affects the deformation in the medium and the values of physical quantities decrease with an increase in the thickness of the slab.

Suitability of standardized single-number ratings of impact sound insulation for wooden floors – Psychoacoustic experiment

Wooden floors usually have worse impact sound insulation (ISI) at low frequencies than concrete floors having the same rating level. Rating level is usually expressed by single-number quantities (SNQs), such as weighted normalized impact sound pressure level Ln,w. Psychoacoustic research among wooden floors is very limited although a controlled laboratory experiment is the strongest method to point out the most adequate SNQs to be declared for the floors. The purpose of our study was to determine how four standardized SNQs of ISO 717-2, Ln,w, Ln,w + CI, Ln,w + CI,50, and LiA,Fmax,V,T, and a recently proposed SNQ, Ln,w + CI,25, are associated with the annoyance of natural impact sounds transmitted through wooden floors. Fifteen floors were built in the laboratory based either on cross-laminated timber (heavy) or open box wood (light) slabs. Different coverings and suspended ceilings were applied on these slabs. The ISI was tested within 25–3150 Hz using both tapping machine and rubber ball. Thereafter, five natural impact sounds were recorded for each floor: rubber ball drops, steel ball drops, walking, jumping, and chair pushing. Fifty-two people rated the annoyance of these 75 recorded natural impact sounds in psychophysics laboratory. Annoyance was best associated with Ln,w for all the five impact sound types. That is, measurement of ISI within 100–3150 Hz is sufficient from subjective point of view. All four SNQs based on tapping machine explained annoyance better than the SNQ based on rubber ball. Our results can significantly guide the future research, development, and regulations of wooden floors.

Analysis of the out-of-plane buckling collapse of a masonry wall: A case study

This paper presents the methodologies followed and the analyses performed to interpret the out-of-plane collapse of a masonry wall located on the fourth floor of a historical building in Palermo (Italy). The collapse mechanism was related to the slenderness of the wall and the presence of ineffective tie rods, unable to restrain the wall. Moreover, the collapse involved the wooden slabs, loaded under the impact of the wall. The case is analysed by examining the crack pattern, the constructive features and the kinematic of the collapse. Finally, a theoretical interpretation of the buckling mechanism is made through non-linear Finite Element (FE) analyses combined with simplified models provided in the literature, showing as reliable considerations can be made by combining two levels of analysis.

An Investigation into the Strength Properties of Three Reclaimed Structural Timber Joist Within the University of Ibadan Community

Background and Objective: The investigation presents the results of selected test assessment on physico-mechanical properties of three selected wood residues within the University of Ibadan Campus, Oyo State, Nigeria. Often, reclaimed planks were considered as useful material for heating and energy production, hence, potential re-usability of these residues for plate rack production were determined. Materials and Methods: Four planks of the selected three wood samples each were collected from the University of Ibadan community. The 12 pieces wood samples were cleaned, plained, and converted into required dimension; samples were dried to about 12%moisture content before tests. Selected physico-mechanical properties test (moisture content, volumetric shrinkage, modulus of elasticity, and modulus of rupture were carried out according to ASTM standards. The data obtained were subjected to analysis of variance (ANOVA). Results: The results of mean density show that <i>Gliricidia sepium, Milicia excelsa </i>and <i>Funtumia elastica </i>had 1032±0.97kg/m³, 548±0.57kg/m³ and 613±0.33kg/m³, respectively. The mean value for moisture content of <i>G. sepium, M. excelsa and F. elastica</i> ranges from 12.47±1.21, 20.84±1.21 and 18.13±1.21, respectively. While, volumetric shrinkage of <i>G. sepium, M. excelsa and F. elastica </i>ranged from 20.55±2.79, 7.48±2.79 and 11.43±2.79. The <i>G. sepium, M. excelsa and F. elastica </i>had MOE values of 8793.13±643.43 N/mm², 8083.64±643.43 N/mm² and 4299.54±643.43N/mm². The mean values for MOR of <i>G. sepium, M. excelsa and F. elastica </i>ranges 404.69±12.362 N/mm², 434.27±12.36N/mm² and 388.34±12.36N/mm². Conclusion: <i>Gliricidia sepium </i>wood had the highest mean density, low shrinkage value and modulus of elasticity. Therefore, it was found most suitable wood slab for plate rack production from reclaimed wood joist.

Diversity of properties of sawmill residues used as feedstock for energy generation

Sawmill residues are used in the power industry, where it accounts for the greatest portion of solid biomass used in combined heat and power plants and heat-generating plants, mainly as chips. This results in increasing demand for this material around the world, which makes the characteristics and variability of sawmill biofuels increasingly important. The objective of this study was to determine the energy-related properties of Pinus sylvestris L. residues depending on the tree growth site (five locations), date of harvest (autumn, winter) and the type of biomass (sawdust, wood slabs). These three factors were found to significantly diversify a large majority of the sawmill residue properties. Sawmill residues had higher LHV compared to the level generally determined for wood (of similar moisture content), and the type of sawmill residue explained to the greatest extent the variability of the largest number of attributes. Wood slabs generally had worse properties than sawdust, and the differences between the forest districts were identical with the influence of the location. In the case of the harvest date, it was found that the source of variability was in fact, inter alia, "nested" in the season of the relative air humidity.

Simulation of impact force generated by an ISO tapping machine on a wooden slab using explicit dynamics analysis

Application of simulation tools to compute impact sound insulation properties of wooden floors has raised interests in recent decades. To achieve accurate results from the prediction models, information from force excitation generated by impact sound sources is required. The purpose of our study was to present a validated procedure to determine the non-linear impact force excitation generated by an ISO tapping machine. The method comprised use of finite element method (FEM) and explicit time integration to compute impact force pulse generated by a hammer of the tapping machine. With a post-processing procedure, the force pulses can be converted to present point forces describing the continuous operation of the tapping machine on the floor. To demonstrate the applicability of the method, the finite element model was applied to imitate an experimental situation on a cross-laminated timber (CLT) slab. The model validation showed that the computational model closely predicts the force pulse generated on the CLT slab. Findings from a sensitivity analysis revealed that local properties of the slab were the most important to the simulated impact force pulse. The findings of the analysis are helpful for those developing simulation tools to compute the impact force generated by the tapping machine on wooden floors.

RESEARCH OF WOOD BOARD MATERIALS ON WATER ABSORPTION

The analysis of the water resistance of currently used wood slabs is carried out. This article examines the water absorption of wood slab materials, as these materials are widely used in the furniture industry, the production of building materials. As a result of the conducted research, it was found that medium-density fiberboard is more moisture-resistant than chipboard.

ПОЛНОСТЬЮ РЕЦИКЛИРУЕМЫЕ ЗВУКОПОГЛОЩАЮЩИЕ ПАНЕЛИ ДЛЯ ШУМОЗАЩИТНЫХ ЭКРАНОВ

There are thousands of kilometers of noise protection screens around the world along roads, railways and near airports. The use of such screens poses some issues. Barriers often lack the required level of sound absorption and have low durability. Screens can be noise-absorbing, noise-reflecting or both. Sound absorbing materials are used to suppress noise at medium and high frequencies. For sound deadening at low frequencies, resonant absorbers are used; they are Helmholtz resonators combined into a single structure. When panels reach the end of their life cycle, they must be recycled. Separating wood, metal, fiberglass or rock wool slabs wrapped in fiberglass is not easy. The production of mineral fiber requires a lot of energy. A selection of materials has been proposed and the properties of fine-grained concretes for the further manufacture of a noise-protective panel have been investigated. The perforated front and blank rear walls are made of fine-grained basalt fiber-reinforced concrete reinforced with alkali-resistant basalt fibers. The results of studies of fine-grained basalt concrete confirmed the effectiveness of the combined use of basalt fibers and superplasticizer Master Glenium 115. The physical and mechanical characteristics of basalt fiber-reinforced concrete are increased by about 70–80 % compared to traditional concrete, which will further increase the durability of imitation noise protection panels.

Vibration level reduction by floor coverings installed on wooden slabs

Effect of floor coverings on impact sound insulation can be described with a vibration level reduction (Δ La). In this study, tests with two floor coverings, eight wooden slabs and with a concrete mock-up slab were conducted by applying the method presented by Sommerfeld and the standard ISO 16251-1. The aim was to study the differences affecting the measured Δ La and the behaviour of the floor coverings installed on different slabs. The results suggest that the Δ La on concrete slabs do not correspond with the Δ La on wooden slabs. Thus, the floor coverings should be measured on wooden slabs when they are to be used within the timber construction industry. The results also show that the coverings should be measured on the wooden slabs where the products are expected to be used. In addition, a standardized test method for the wooden slabs corresponding the method of ISO 16251-1 should be developed.

INVESTIGATION OF EFFECT OF USING NANO COATING ON WOODEN SHEDS ON DYNAMIC PARAMETERS

In this article, the dynamic parameters (frequencies, mode shapes, damping ratios) of the uncoated wooden shed and the coated by silicon dioxide are compared using the operational modal analysis method. Ambient excitation was provided from micro tremor ambient vibration data on ground level. Enhanced frequency domain decomposition (EFDD) was used for output. Very best correlation was found between mode shapes. Nano-SiO2 gel applied to the entire outer surface of the red oak shed has an average of 14.54% difference in frequency values and 13.53% in damping ratios, proving that nanomaterials can be used to increase internal rigidity in wooden slabs. High adherence of silicon dioxide to wooden surfaces was observed as another important result of this study.

Selected geotechnical issues related to the foundation of drilling rigs

This article presents selected geotechnical issues occurring at the foundation of drilling rigs for geological works included in the Operation Plan of a company performing geological works, in the aspect of designing and construction of their foundations and a yard. In the construction of drilling equipment, at least two main zones can be distinguished, often requiring separate foundations for individual machines: the zone near the borehole, including crane components, mast and drill pipe drive, and the so-called machine hall zone, including drive units and elements of mud system. The machine foundation is designed to mount a particular type of machine on it in order to transfer to the ground the static and dynamic loads generated during the movement of the machine. In particular, the current legislation, technical literature and standards were reviewed, especially: API recommended practice 51R and 4G, Working platforms for tracked plant, Eurocode 7 PN-EN 1997-2:2009 Standard. The values of safe bearing capacity of some soils and the magnitude of pressures generated by static and dynamic loads of selected drilling equipment were presented, which can be useful for preliminary assessment of the location of drilling equipment in the field and selection of surface and type of foundations. Typical examples of foundation of drilling rigs in various geotechnical conditions on direct foundations with the use of prefabricated elements such as reinforced concrete road slabs, wooden slabs and composite slabs based on HDPE plastic or on indirect ones with the use of micropiles were described. The following essential elements of the process of geotechnical design of the foundation of drilling rigs and their execution were indicated. According to legal regulations, the form of presentation of geotechnical foundation conditions and the scope of necessary tests should depend on assigning the building structure to a proper geotechnical category, which for practical purposes is tabulated in this article. The design and construction of foundations for drilling rigs should ensure, among other things, that their intrinsic vibrations are sufficiently different from those induced by subassemblies of the rig, that the vibration amplitudes are smaller than permissible, and that the foundations of individual machines are adequately separated from each other and from the rest of the facilities (yard). Conclusions on the safe foundation of drilling rigs on the ground, including, among others, the strengthening of the ground, design of independent building structures such as foundations for drilling rigs and their execution and removal were presented.

Eco-Efficient False Ceiling Plates Made from Plaster with Wood and Plastic Residues

Large amounts of different types of waste are generated each day in the world. Most of them do not receive proper management at the end of its useful life. In that sense, and trying to apply eco-efficiency criteria, the construction sector has recently been working on the design of new building materials that incorporate some types of residues. Those new construction materials improve some of the properties given by traditional options, such as thermal conductivity or lightness. However, many types of research in which new building products are generated do not exist. Subsequently, this paper aims at generating new gypsum plaster false ceiling plates by incorporating two different types of residues: wood waste from the demolition of traditional wooden slabs and polycarbonate (plastic) waste from crushed rejected CDs and DVDs. The flexural strength of the developed plates is tested using the procedure described by UNE-EN 14246. Furthermore, the thermal conductivity of the new pieces is obtained following the method defined by ASTM D5930-09. The results show that for all the scenarios under study when wood and plastic waste is added to the plates, the lightness and the thermal conductivity of the pieces improved. In addition, in some scenarios, the incorporation of polycarbonate waste is linked to an improvement in the mechanical behaviour of the pieces compared to the reference plate. On the other hand, when wood waste is added to the mixtures, the flexural behaviour of the plates decreases, but always achieving the minimum requirements made by the standards. Finally, it must be said that adding waste to the plasters, the amount of gypsum powder used to generate the plates decreases considerably, which represents a significant improvement in the eco-efficiency of new products.

Mathematical Modelling of Pyrolysis of Hardwood (Acacia)

Abstract This paper emphasises the analogous modelling of hardwood (acacia) pyrolysis. The impacts of physical characteristics of hardwood chips on the pyrolysis are examined through the conservation of biomass solid mass fraction. The ONORM standard chips of sizes ‘G30’ and ‘G50’ and their combination are individually tested in the pyrolysis reactor. In the analogous situation, the fixed bed is assumed to be a wooden slab with a porosity equivalent to the voidage of bed. Bulk density, bed length and porosity are several of the physical attributes of a fixed bed used to examine the variation in the hardwood solid mass across the fixed bed. To measure temperature, the four-temperature sensors separated from each other by 80 mm are fixed along periphery of a reactor. The heating element of 2 kWe is provided to initiate the biomass pyrolysis. The proposed model is also used to establish the relationship between the kinetics of pyrolysis and the structural properties of hardwood.

Assessing Wood Waste by Timber Industry as a Contributing Factor to Deforestation in Ghana

This study assesses the wood waste generation, its management practices, and its effects on the forests in Ghana. The rate of logging in Ghana has increased and this can be attributed to the increase in the establishment of Sawmilling companies in the country. Increased in the installation of sawmilling companies has increased the sawn timber production. The use of outmoded milling machines has led to an increase in waste generation. An increase in production has led to an increase in the annual allowable cut in the country, which has overrun the limit of sustainable forestry. A qualitative research method was employed for the research work. A well-structured questionnaire was administered to the study to solicit the views of the wood industries about wood waste generation and its management practices. The study population comprised of 50 sawmilling companies. From the data collected, it was observed that most of the timber production companies do not know how to manage the waste generated and the waste is left un-utilized. In general 80% of the timber production companies responded that they have an idea of wood waste management but do not have the technical know-how to manage the waste. It was observed that 80% of the timber production companies do not manage the waste they generate during their operations. Wood shavings, sawdust, wood slabs, offcuts, branches, and others are left un-utilized. From the observations made in the visited sawmills, chunks of waste are generated on the site. The fact that the wood which is un-utilized (waste) and the wood, which is utilized as sold products, are equal in cost to the company which highlights the poor material and cost-efficiency. Wood industry materials and cost efficiency, together with waste management practices and their contribution to deforestation in the country, are discussed.

WHEN SANTIAGO DE COMPOSTELA AND MONDOÑEDO WERE BUILT IN WOOD: HALF TIMBER WITH EARTH CONSTRUCTIONS IN THE CITIES OF GALICIA

Abstract. Nowadays, more common traditional constructions in Galician historical cities are houses with stone walls and wood slabs. However, Galician medieval cities were built with half timbers with earth and bricks used as structural closures and recovered interiorly with mud and lime mortars. At that time, Santiago de Compostela and Mondoñedo were two cities built in wood, not in stone and these half timbers were the most widespread technique in these cities until the XVIII and XIX. Only a few examples can be seen at present. These constructions are on the brink of disappearance due to three main factors: the lack of general public knowledge, the lack of Government protection and, finally, the lack of building professional training in the aforementioned techniques.

Determination of the critical conditions leading to the ignition of decking slabs by flaming firebrands

This study investigates the ignition by flaming firebrands of two decking slabs used in French dwellings located in Wildland–Urban Interface. The first decking slab was made of pine and the second one was a thermoplastic composed of polypropylene and calcium carbonate. Flaming firebrands were produced by heating and igniting wood chips of different shapes (square, longitudinal and rectangular) with a cone calorimeter. The firebrands generated preserved their shape during their heating. Their projected area was between 0.07 and 12.00 cm2 and their mass ranged from 0.57 mg to 2.66 g. The location of flaming firebrands, the minimal mass and the minimal number of firebrands needed to ignite the slabs were analysed in order to determine the critical conditions of ignition. The ignition of the decking slab only occurred when the firebrands were positioned at the interstices of the wooden slabs and against the leg of the thermoplastic slabs. No ignition occurred when the firebrands were located on the surface of the decking slab. A minimum mass of firebrands of 0.31 g and 0.80 g was necessary to ignite the wooden slabs and the thermoplastic ones, respectively. Less firebrands were needed to ignite wooden slabs than thermoplastic ones.

Prospects of biomass wood wastes as natural dye stuffs for batik clothes and other woven fabrics

The undertaking of abundantly biomass wastes generated from forest-related timber industries, e.g. wood slabs, bark, leaves, sawdust, and other waste form is still limited. Attempts are necessary to utilize those wastes into useful renewable products for example natural dyes for batik cloths and woven fabrics, which implement environmentally friendly technologies. Relevantly, this scrutiny aims to elaborate on the exploration, processing, and utilization of those wastes into natural, easily produced, and applicable dyestuffs. Biomass wastes are converted into dyes in liquid, paste, and powder forms. Dye production commences with a chemical investigation of biomass wastes in those three forms. All wastes were sorted, dried, grinded, and extracted. The resulting dyes, before being applied to the batik cloth and other woven fabrics, were fixed using inorganic chemicals, e.g. lime (CaCO3), alum (Na2Al2O4), and ferro-sulphate (FeSO4) to strengthen the color. These results are applicable as basic as well as complimentary colors for batik cloths and weaving yarns. Expectedly, in qualities, the dye products could compete with or even partially substitute the imported synthetic pigments. The positive impact is this technology could improve economic welfares of forest-surrounding communities.

Assessment of Community-led Total Sanitation Sustainability in Ejigbo Local Government Area of Osun State, Nigeria

Nigeria is among the nations of the world with the highest number of people practising Open Defecation. This study among others assessed the level of community-led total sanitation (CLTS) in the selected triggered communities and focused on the rationale for the reversion of CLTS programme implemented in some of some rural communities with poor sanitation coverage in Ejigbo Local Government Area of Osun state, Nigeria, with the technical and financial support of donor agencies. The qualitative, semi-structured questionnaires were administered in 296 households in 41 selected communities. Spatial positioning of communities and water points coordinates were collected through the use of a hand-held Global Positioning System- GPS model etrex 10 GARMIN to produce a digital map through the Arc view Geographical Information System software. Two batches of CLTS were conducted in the Local Government Area across 182 communities in 2006 and 2012 with and without subsidy. Communities were triggered and declared open defecation free while some were certified ODF. The majority (75.7%) of the respondents reverted to OD as a result of caved-in of pit latrine due to the use of log of wood, wooden slab as platform over the pit. 5.1% of the respondents improved on CLTS latrine 81.7% of household used the latrine for just two years before defectiveness set in. All respondents agreed to have benefited in the CLTS programme and were willing to return to construct durable latrine provided they get a subsidy or are financially buoyancy. This study revealed that emphasis was on latrine construction while other components of environmental sanitation were not properly addressed as any scalability was near to nothing. Monitoring and follow up was found to be weak among the stakeholders.