Papers by Paweł K Kozakiewicz
Sustainability
Sustainable development should take into account the conservation and preservation of architectur... more Sustainable development should take into account the conservation and preservation of architectural features characteristic of a given cultural area for future generations. Chemical, physical and mechanical properties of timber components are key to assessing the technical preservation of historical timber structures, defining proper restoration methodology and extending the durability of timber structures. Moreover, this evaluation will help to elaborate assessment criteria to decide between the restoration or replacement of a given antique structure. The article presents a method of assessing a historical wooden structure on the example of an antique decorative wooden floor from the beginning of the 19th century, preserved in the Tarnowiec Manor House. It determines tests and scientific analysis as a tool for a decision of possibilities of further usage of the historical floor structure. We performed tests and scientific analysis by calculating the functional properties of the par...
Was für Mittel hat man gegen die Fäulung [Sturm 1713] Das erste ist die Kälte, welche beydes, die... more Was für Mittel hat man gegen die Fäulung [Sturm 1713] Das erste ist die Kälte, welche beydes, die innerliche Bewegung auffhält, und die von aussen herzukommende Ursachen der Fäulung abhält: das andere ist die Hitze, doch nicht eine schwache, sondern hefftige, und welche das, was zur Fäulung dienet außtreibet; zum Exempel ist gebraten Fleisch , gedörrte und geräucherte Sachen, die durch Feuers=Brunsten gereinigte Lufft etc. Das Dritte ist die Außwitterung (ventilatio) oder Schwingung in der Lufft, wodurch die zur Fäulung geneigte Theilgen außgetrieben und durch das Wähen der Lufft zerstreuet werden; da im Gegentheil die Abhaltung und Außschliessung der Lufft, nemlich so fern sie stillstehet und träg ist, das vierte Mittel ist, wie solches mit vielen Erfahrungs=Proben kan erwiesen werden; weil nemlich die Lufft die Cörperlein, welche eine solche unordentliche Bewegung entweder befordern, oder von neuem erregen, herzubringet. Einige Practische Anmerckungen ... über die Kentniß des Bauzeugs [1745] Das Holz, welches im Hauen nicht dauret, leicht wurmstichicht wird, und faulet, soll man in Gebäuden, die lange stehen sollen, entweder gar nicht brauchen, wo man einen anderen Zeug davor nehmen kann, oder, wo es nicht angehet, theils den übrigen Gebrauch des Holzes vermeiden, theils auch selbst, unter dem Holz eine geschickt Wahl treffen. Das Tännene bleibt zwar fein gerade, aber es wird leicht wurmstichig, das Eichene dauert wohl in der Erde, und wird im Wasser fast zu Stein; allein es zieht sich leicht in die Krümme und bekommt Ritze, und im Wasser ziehet sich eine schwarze Materie aus demselben, wovon die Fische sterben. Pappeln und Linden sind sehr weich, und dem Bildhauer zum Schnitzwerk dienlich. Die Erle hält sich gut in sumpfichten Orten, und kann ungeheuere Lasten tragen; da hingegen Fichten sich gar zuleicht sencket. Es wird aber das Holtz von einerley Art nicht von gleicher Güte befunden. Das Holz, welches geschwinde wächst und dicke wird, soll stärker, fester und dauerhafter seyn, als das langsam wächst und dicke wird, folglich das Holtz besser seyn, welches breite Jahre hat, als welches schmale Jahre hat. So bemercket man auch, daß das Holz , welches inwendig hohl, leicht faule; und daß das Holtz, welches an erhabenen Oertern wächst, trockner und fester sey als das an niedrigen, sonderlich sumpfigten und morastigen Orten wächst. Daher auch einige wollen, man soll das Holtz von einerley Art alles aus einem Walde nehmen, damit es überein daure. Vornehmlich muß das Bau-Holz recht trocken seyn; wiedrigenfals es erst im Gebäude trocknet, schwindet und sich wirft, wodurch nicht nur am Gebäude selbst, sondern auch an Fuß-Böden, Thüren, Rahmen, u.d.g. grosser Schade entstehet, und dem Bewohner viele Beschwerlichkeit dadurch zugezogen wird. Damit man nun diesem Mangel begegne, muß man das Holz nicht allein zu einer Zeit
Niniejsze opracowanie przygotowano z myślą o szerokim i racjonalnym wykorzystaniu drewna w konstr... more Niniejsze opracowanie przygotowano z myślą o szerokim i racjonalnym wykorzystaniu drewna w konstrukcjach drewnianych. Krok po kroku - od bazy surowcowej, poprzez przerób, po materiały finalne - przedstawiono szereg istotnych i przekrojowych zagadnień z zakresu inżynierii konstrukcyjnych materiałów drzewnych i drewnopochodnych, stawiając szczególny nacisk na problematykę produkcji i sortowania tarcicy konstrukcyjnej. W opracowaniu zawarto informacje zarówno z zakresu budowy, wad i właściwości drewna, jak i uregulowań normalizacyjnych, a także przegląd technik przetarcia i analizy działania maszyn sortowniczych.
Anizotropowe i niejednorodne (obciążane wadami) drewno może być przetworzone na różnorodne materiały inżynierskie o pożądanej charakterystyce właściwości. Tak zrodziła się idea a potem rzeczywista produkcja konstrukcyjnych tworzyw inżynierskich na bazie drewna. W niniejszym opracowaniu przybliżono strukturę przemysłu płyt drewnopochodnych w Polsce oraz przedstawiono informacje o najważniejszych materiałach drzewnych i drewnopochodnych wytwarzanych z cząstek drewna o różnej wielkości.
Książka ta jest znacząco rozbudowaną (poszerzoną) i zmodyfikowaną (zaktualizowaną) wersją wcześniejszego opracowania pt. „Inżynieria materiałów drzewnych”, wydanego w 2012 roku, które z kolei ma swój początek w skrypcie pt. „Wytrzymałościowe sortowanie tarcicy budowlano-konstrukcyjnej”, wydanym w 2005 roku.
Coatings
The wood of five European species: black poplar (Populus nigra L.), European beech (Fagus sylvati... more The wood of five European species: black poplar (Populus nigra L.), European beech (Fagus sylvatica L.), European ash (Fraxinus excelsior L.), European oak (Quercus robur L.), and Scots pine (Pinus sylvestris L.) was subjected to thermal modification in nitrogen atmosphere at 190 °C during 6 h. Native and modified wood was varnished and oiled in industrial conditions. Thermally modified (TM) wood was characterized by a greater absorption of varnish and oil when applying the first layer to the surface, which finally resulted in higher application values compared to native wood. In particular, after varnishing, there was a significant increase in gloss and radical change of colour. Regardless of the wood species, finishing process (varnishing, oiling), the ΔE values were close to or higher than 6, which proves high colour changes. Modified poplar, ash, and oak after varnishing had a different colour (ΔE higher than 12). The surface colour changes as a result of UV photoaging was indiv...
Novensia, 2017
She was professor of Classical Archaeology, an outstanding scholar, member of the Société des Ant... more She was professor of Classical Archaeology, an outstanding scholar, member of the Société des Antiquaires de france, founder member of the Associazione Antropologia e Mondo Antico and the Associazione Italiana per lo Studio e la Conservazione del Mosaico. She was on the staff of the Dipartimento di Scienze Psicologiche, della Salute e del Territorio dell' Università degli Studi Gabriele d' Annunzio in Chieti-Pescara in Italy. Born in Seregno (Milan) in 1950, Sara read archaeology with the famed Prof. Guido Achille Mansuelli in Bologna and completed her degree in 1973. Two years later she began as a researcher at the Dipartimento di Archeologia Università di Bologna. In 1997-2009, she was hired as a full professor of archaeology and Greek and Roman art history at the University of Parma. She was also associated with the Scuola di Specializzazione in Archeologia at the University of Bologna in 1998-1999. She was appointed a professor of the Gabriele d' Annunzio University in Chieti-Pescara in 2009. Lecturing and doing research, she also held important university posts, surrounded by her students and collaborators. She was a dedicated scholar of Greek and Roman urban planning as well as ancient craftsmanship. She also took an interest in archaeometrics, pottery studies and Roman painting. from 1982 to 1994 she headed the Museo Civico Archeologico di Bazzano (Bologna). It was then that she studied the museum oil lamp collection. from 1988 to 2005 she directed the research at Castelraimondo (forgaria nel friuli, Udine), a subalpine fortified site inhabited from prehistoric to medieval times. Polish students of archaeology from the University of Warsaw took part in this research.
Shrinkage and density of archeological wood from 17th century pavement. In Central Europe, in the... more Shrinkage and density of archeological wood from 17th century pavement. In Central Europe, in the 17th century. The custom of reinforcing and laying roads with wood was preserved. The remains of these structures are still found in many places and its' material is often in surprisingly good condition. As part of the work, selected physical properties of pine wood found at the depth of 1.5 m, constituting a part of the road laid around 1680, were examined. The condition of the wood was varied. This wood was characterized by high initial humidity, high longitudinal contractions and low density after drying. The process of drying the wood was accompanied by the formation of numerous transverse cracks and deformations.
Forests, 2021
Transport of wood biomass is one of the key operations in forestry and in the wood industry. An i... more Transport of wood biomass is one of the key operations in forestry and in the wood industry. An important part is the transport of shredded wood, where the most common forms are chips and sawdust. The aim of the research was to present the variability of the total weight of trucks (gross vehicle weight, GVW), the weight of the empty trucks (tare), and loads of chips and sawdust in different periods of the year. Changes in specific parameters were analyzed: GVW; tare weight; trailer capacity; use of the trailer load capacity; bulk volume and bulk density of wood biomass loads; solid cubic meter (m3) and weight of 1m3 of the load; and load weight depending on the season, with simultaneous measurements of wood chips and sawdust moisture. More than 250 transports from four seasons of the year were analyzed in the research. It was found that the total weight of trucks (GVW) was at a comparable level, on average from 39.42 to 39.64 Mg with slight differences (with SD 0.29 and 0.39). The w...
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology, 2016
Influence of ultraviolet radiation on colour of European ash sapwood and heartwood (Fraxinus exce... more Influence of ultraviolet radiation on colour of European ash sapwood and heartwood (Fraxinus excelsior L.). This paper examines the influence of ultraviolet radiation on the colour of ash wood, used principally as flooring material or in veneer and furniture manufacturing. The colour parameters were determined using the CIE L*a*b* and CIE L*C*h colour space model. The research results show a small decrease in wood lightness, by 7% in sapwood, and by 5% in heartwood, after 300 h exposure to radiation. Material change towards yellow was, however, observed in the colour of in both sapwood and heartwood. After 300 h exposure, the b* parameter increased 2 and 1.5 times for ash sapwood and heartwood, respectively. The highest total colour difference in ash sapwood and heartwood was observed after 20 h exposure. The total colour difference as a result of ultraviolet radiation was nearly twice as high in sapwood as it was in heartwood.
Wood Research, 2016
Comparative research was conducted on shear strength parallel to grain of heartwood of Scots pine... more Comparative research was conducted on shear strength parallel to grain of heartwood of Scots pine (Pinus sylvestris L.) from the 16-18th century from Central Poland and of modern wood. Tests were performed on 150 samples of aged wood from 13 construction elements of 4 historic buildings and on 100 samples from 10 modern constructional elements. Aged wood revealed a better technical quality. The difference of average shear strength parallel to grain values equaled 0.09 MPa and the translation of correlation line was about 0.35 MPa in favour of aged wood.
Wood Research, 2016
Oak wood is characterized by a high resistance to effects of biotic factors and thereby it is oft... more Oak wood is characterized by a high resistance to effects of biotic factors and thereby it is often found in archaeological excavations. While lying over many years in the wet environment, the wood turns black as a result of reaction with iron compounds. Archaeological oak is a valuable raw material. In this paper selected mechanical and chemical properties of a thousand years archaeological oak were investigated. Then the archaeological oak properties were examined and compared with the contemporary oak wood. Archaeological oak wood as well as contemporary oak wood has a directly proportional relationship between MOE (modulus of elasticity) and wood density, and similar relationships between wood density and compressive strength, bending strength, content of mineral substances. Contemporary wood of the same density as the archaeological oak wood would show significantly higher mechanical properties.
The process of wood bending displays measurable departures from the standard beam theory. The mos... more The process of wood bending displays measurable departures from the standard beam theory. The most well-known departures are caused by shear. In the mathematical part of this work we found and analysed full plane stress of wood which occur in III-point and IV-point loading. Hill-type strength criteria have been used. The role of shear is determined by the relation between shear spandepth ratio and bending-shear strength ratio. Three types of this relation have been defined, one of which specifies the concept of medium length beam. In the second part of this work we statistically described bending-shear strength ratio for European, American and exotic wood species. On this basis, we determined the shear span-depth ratio of the medium beam. The role of shear stress in the bending strength test of medium beam cannot be omitted. The work contains elements of strength theory from a historical perspective, especially concerning strength criteria. Given one result of the contact mechanics.
Determination of the wettability of gaboon wood (Aucoumea klaineana Pierre). The examined gaboon ... more Determination of the wettability of gaboon wood (Aucoumea klaineana Pierre). The examined gaboon wood is used in European countries mostly for the production of plywood, windows and elevations. In this work, the wettability of gaboon wood was determined on the basis of the sessile drop method, using wood contact angle measurement with water and diiodomethane. The characteristics determined were the surface free energy for wood, wetting energy, spreading coefficient, work of adhesion and surface tension for the wood-water and wood-diiodomethane structure. The course of the wettability process, particularly in case of polar liquid (water), demonstrates significant dynamics. Satisfactory stabilization of the process occurs after about 30 sec from placing a droplet, and this time should be considered optimal. The presence of striped and irregular grain translates into an increase of the changeability of the tested surface wettability indicators.
A study of selected features of Shan Tong variety of plantation paulownia and its wood properties... more A study of selected features of Shan Tong variety of plantation paulownia and its wood properties. The study was conducted on three-year-old and representative paulownia tree of the Shan Tong variety, from a plantation in the Kujawsko-Pomorskie Voivodeship, Poland. The three-year-old paulownia tree was 4.2 m high and its diameter at butt level was of 11 cm. The tree provided material for the study from its three-year-old shoot, which was divided into three parts: leaves, branches and the main trunk. According to calculations, this typical paulownia tree (a three-year-old shoot) from a plantation accumulated 4.664 kg of carbon in the part above the ground level, which corresponds to the absorption of 17.101 kg of CO2 from the atmosphere. Taking into account the underground part of this plant, it can be estimated that it absorbed over 30 kg of CO2 (on average, ca. 10 kg CO2 per year). The density of paulownia wood in absolute dry state was ca. 250 kg/m 3 . The width of annual growth r...
Purpose: The need to increase women's access to extension has been extensively discussed. This pa... more Purpose: The need to increase women's access to extension has been extensively discussed. This paper assesses women's access to extension services through the Plantwise extension approach as a baseline for future comparison of women's access through other extension approaches. It also assesses whether crops that men and women farmers seek plant health advice on are similar or not, and attempts to disperse assumptions that continue to be made about what crops women and men grow. Approach: We analysed data from the Plantwise Online Management System for 13 countries using descriptive and inferential statistics. Findings: We show that the Plantwise extension approach enables higher levels of women's access than generally reported for agricultural extension, that the crops that women and men seek extension advice on is not gender dependent, and there are few clear distinctions between their crops of interest. Practical implications: There is limited literature studying gender inclusiveness in different extension approaches. The findings add to the documentation of assessing women's access to demanddriven extension. Theoretical implications: Plantwise is a new extension approach which needs to be assessed from spatial and temporal perspectives to understand whether demand-driven extension enables increased women's access over time. Originality/value: Extension service provision is often based on assumptions about what crops are being grown. Small studies have challenged these assumptions, but this large dataset enables us to test these assumptions more thoroughly across 13 countries adding to the weight of evidence against the existence of women's and men's crops.
The subject of this paper is testing the hardness of two-layer floor materials with top layer mad... more The subject of this paper is testing the hardness of two-layer floor materials with top layer made of ash wood in tangential cut, and bottom layer made of pine wood, radial cut, with cross wood fibre layout in both layers. Tests were carried out for top layer thickness 6.6 mm, 4.0 mm and 2.0 mm. Strong correlations were noticed between the hardness of floor elements and the density of the top layer for each thickness variant. Overall statistically significant influence of bottom layer density on the hardness of two-layer floor elements was observed in samples whose top layer was 2.0 mm thick.
The main objective of this research was to determine the fibre saturation point of tropical wood.... more The main objective of this research was to determine the fibre saturation point of tropical wood. Two different methods were used to achieve this aim: the logarithm of strength properties versus moisture content and volumetric shrinkage-moisture content plot to zero shrinkage. The test included selected wood species from Africa: Opepe, Iroko, African padouk, and Wenge, and South America: American mahogony and Ipe. For comparison, selected domestic wood species of a similar structure – European beech (Fagus sylvatica L.) – were also tested. Determination of the fibre saturation point of the selected wood species using two methods delivered similar results (the small differences were not significant). The results showed that, generally, the fibre saturation point of the tropical wood species was lower than in the case of the European wood species. The lowest values of the fibre saturation point were shown by the African padouk and Ipe (approx. 17 %). Moreover, it was found that in the...
Bioresources, 2019
Black poplar (Populus nigra L.) was subjected to thermal modification in superheated steam. The m... more Black poplar (Populus nigra L.) was subjected to thermal modification in superheated steam. The modification was performed at 160 °C, 190 °C, and 220 °C for 2 h. The equilibrium moisture content of the black poplar wood was examined when it was exposed to 76% ± 2% relative humidity at a temperature of 20 °C ± 2 °C. The thermal modification of the poplar wood changed its moisture-exchange-related physical properties to a large extent. The effects of temperature on individual properties (density, mass loss, hygroscopicity, swelling, and water absorption) were diverse, and the intensity of these effects increased with increasing temperature of the thermal treatment process. In most cases, no significant differences were observed between the changes in properties of the sapwood and the heartwood.
Wood is a fibrous orthotropic material additionally characterized with sign-sensitivity. Thus, de... more Wood is a fibrous orthotropic material additionally characterized with sign-sensitivity. Thus, determining the universal conditions of its strength constitutes a complex task. In their work, the authors present the anisotropic generalization of the Huber criterion which is closer to Norris's proposal, as opposed to Hill (and Hofmann) and Mises proposal. The obtained criterion incorporates conditions which are additionally imposed on a special case of Tsai-Wu criterion for composite materials.
Drvna industrija, 2021
The main objective of this work was to evaluate the effects of flat slicing processes on wood sur... more The main objective of this work was to evaluate the effects of flat slicing processes on wood surface characteristics of the European beech (Fagus sylvatica L.). The relation between wettability, roughness and machining methods were studied. Two different wood thickness (3.4 and 4.0 mm) and three levels of compression during slicing (67.5 %, 57.5 % and 47.5 % of desired veneer thickness) were used to prepare surfaces prior to testing. The smaller variation of the thickness of thinner veneers was observed. No significant impact of compression on variation of the thickness was found. The contact angle was lower when roughness measured parallel to the grain was higher. The influence of selected compression on roughness of European beech veneers measured perpendicular to the grain was confirmed. This indicated that the influence of the set of machining processes, such as pressure bar setting during slicing, is significant for wooden veneers surface properties.
BioResources, 2020
Black poplar (Populus nigra L.) was thermally modified in superheated steam at 160 °C, 190 °C, an... more Black poplar (Populus nigra L.) was thermally modified in superheated steam at 160 °C, 190 °C, and 220 °C for 2 h. The research identified correlations between the chemical composition and selected mechanical properties of thermally modified wood. The higher treatment temperatures significantly lowered the modulus of rupture (MOR) and the Brinell hardness (BH). These correlations were particularly apparent at higher temperatures (190 °C and 220 °C) when thermally modified wood experienced stronger hemicelluloses degradation, which was indicated by an increase in the content of non-structural substances. The wood properties including compressive strength parallel to the grain (CS), modulus of elasticity during bending (MOE), and compressing (MCS) were affected less by the chemical changes caused by the thermal processing of wood. Moreover, the level of wood moisture content also affected these changes.
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Papers by Paweł K Kozakiewicz
Anizotropowe i niejednorodne (obciążane wadami) drewno może być przetworzone na różnorodne materiały inżynierskie o pożądanej charakterystyce właściwości. Tak zrodziła się idea a potem rzeczywista produkcja konstrukcyjnych tworzyw inżynierskich na bazie drewna. W niniejszym opracowaniu przybliżono strukturę przemysłu płyt drewnopochodnych w Polsce oraz przedstawiono informacje o najważniejszych materiałach drzewnych i drewnopochodnych wytwarzanych z cząstek drewna o różnej wielkości.
Książka ta jest znacząco rozbudowaną (poszerzoną) i zmodyfikowaną (zaktualizowaną) wersją wcześniejszego opracowania pt. „Inżynieria materiałów drzewnych”, wydanego w 2012 roku, które z kolei ma swój początek w skrypcie pt. „Wytrzymałościowe sortowanie tarcicy budowlano-konstrukcyjnej”, wydanym w 2005 roku.
Anizotropowe i niejednorodne (obciążane wadami) drewno może być przetworzone na różnorodne materiały inżynierskie o pożądanej charakterystyce właściwości. Tak zrodziła się idea a potem rzeczywista produkcja konstrukcyjnych tworzyw inżynierskich na bazie drewna. W niniejszym opracowaniu przybliżono strukturę przemysłu płyt drewnopochodnych w Polsce oraz przedstawiono informacje o najważniejszych materiałach drzewnych i drewnopochodnych wytwarzanych z cząstek drewna o różnej wielkości.
Książka ta jest znacząco rozbudowaną (poszerzoną) i zmodyfikowaną (zaktualizowaną) wersją wcześniejszego opracowania pt. „Inżynieria materiałów drzewnych”, wydanego w 2012 roku, które z kolei ma swój początek w skrypcie pt. „Wytrzymałościowe sortowanie tarcicy budowlano-konstrukcyjnej”, wydanym w 2005 roku.
Troska o środowisko naturalne i poszukiwania surowców o możliwie niskiej cenie spowodowały, że przemysł płyt drewnopochodnych coraz częściej stosuje rośliny jednoroczne jako substytut drewna,ora szerzej wykorzystuje materiały z recyklingu. W książce omówiono właściwości drewna poużytkowego oraz roślin włóknistych jako wartościowych surowców do produkcji tworzyw drzewnych. W poszczególnych rozdziałach przedstawiono najnowsze maszyny i urządzenia służące do rozdrabniania tych surowców oraz ich transportu w pierwszej fazie produkcji. Schematy urządzeń, ich wydajności i wybrane parametry techniczne opracowane zostały na podstawie materiałów firmy Pallmann Maschinenfabrik GmbH & Co.KG (jednego z największych światowych producentów rozdrabniarek).
This book contains two parts: a theoretical description and tasks. The theoretical part presents knowledge of wood physics, especially: hygroscopicity in wood (e.g. adsorption, wood moisture content, fiber saturation point, equilibrium and maximum moisture content), dimensional changes (e.g. swelling and shrinking), density (e.g. porosity, specific gravity), electrical properties (e.g. electric resistance, electric capacity), heating properties (e.g. thermal conductivity, specific heat, heat of combustion) and acoustic properties of wood. There are a lot of calculation tasks (examples of application) in practical part.
This paper presents an assessment of the effect of temperature and moisture content on compression strength parallel to the grain. The development of this field of wood science has been discussed and the collected information has been experimentally verified on the basis of eighteen selected species of wood with variable density and anatomical structures.
A satisfactory mathematical description of the phenomena relating to strength of materials was made in the second half of the 17th century, which was a stimulus also for development of research on wood. The next century saw research on compression strength of selected species of wood, however, without a due consideration of the effect of moisture content and the buckling phenomenon. In the 19th century, an explicit distinction was made between compression (crushing) of short specimens and a complex mechanism of destruction of slender elements. The turn of the 20th century is a period of an arduous basic research, i.e. determination of the characteristics of physical and mechanical properties including compression strength parallel to the grain for specific levels of moisture content of wood species from various continents. A new quality in testing the compression strength (optimisation of specimens and analysis of the effect of temperature) was forced by the needs of aviation in the first half of the 20th century. The last decades of the 20th century and the present century focus on testing of the above-mentioned characteristics of the material mainly for the purposes of wood constructions in the building industry. At present, compression strength parallel to the grain is readily used as a criterion in assessment of wood, due to the established strong correlation with other properties and simplicity of the test itself. Even so, the testing procedures are not fully standard yet, and the effect of temperature, moisture content, density and the characteristics of an anatomical structure of wood has been analysed only in a fragmentary way.
A unique testing method was developed for the purposes of this paper, with appropriate selection parameters for compression tests of clear wood “multi-twin” specimens, facilitating the examination of the effect of moisture content and temperature. Specimens obtained from a “single board” within the specific species of wood were used, which had been conditioned in groups of 10 pieces for each of the moisture content options, and subsequently heated or cooled without changing the moisture content. The specimens were destructed at a constant speed of increasing deformation equal to 2 mm∙min-1. The testing time of each of the specimens did not exceed 150 seconds.
The values determined for the eighteen species of wood, as a whole demonstrating a wide spectrum of density and variable anatomical structures, allowed to determine the averaged interactions and to describe them with simple (linear) correlations. A strong and directly proportional interaction between compression strength and dry density was established. This relationship is weaker in moist wood. As anticipated, the compression strength of wood tends to decrease, presenting an approximately linear trend, in the entire hygroscopic range along with increase of the wood moisture content, reaching the minimum value with moisture content at the fibre saturation point. Similarly, the strength tends to decrease along with increasing temperature. The effect of temperature is slightly stronger in moist wood. Irrespectively of the averaged interactions, a significant effect of individual characteristics of an anatomical structure and density of respective species of wood is observable, manifesting itself, among others, in significantly different values of conventional moisture content at the fibre saturation point or differences in changes of compression strength parallel to the grain resulting from moisture content and temperature. Various appearances and the nature of distractions of the specimens after the compression test were an evident indication of the effect of the anatomical structures and density of wood.
The correlations of the effect of temperature and moisture content on compression strength of the specific species of wood with variable density and anatomical structures will support quick testing of wood, i.e. not requiring long-term seasoning and conditioning of specimens. It will be possible to recalculate any wood compression strength indicating non-standard moisture content and temperature to the standard reference level. The testing method developed in this research work and the data obtained in this way have a significant value also for the purposes of determination of constructional timber characteristics. Considering cost-effectiveness factors, testing of small, “multi-twin” laboratory specimens and an effective transfer of the achieved results onto full-size constructional timer is more relevant.
Zbiór stanowi uzupełnienie do podręcznika noszącego zbliżony tytuł:
„Klimat a drewno zabytkowe - dawna i współczesna wiedza o drewnie” autorstwa P. Kozakiewicza i M. Matejaka, wydanego przez Wydawnictwo SGGW w 2013 roku (wydanie IV zmienione). Zbiór zadań zawiera praktyczne ujęcie zagadnień omówionych w wyżej wymienionym podręczniku.
W kontekście powyższego nie dziwią gorzkie słowa wypowiedziane przez jednego ze specjalistów od zagadnień konserwacji: „człowiek jest najgorszym wrogiem dzieł sztuki” (Coremans 1967). W otoczeniu ignorancji lub nieuzasadnionej pewności dokonywane są, nierzadko katastrofalne w skutkach, zabiegi konserwatorskie. Obiekty drewniane są narażane na zmienne warunki klimatyczne, które prowadzą do ich trwałych uszkodzeń. W różnych miejscach i odstępach czasowych zdarzają się te same błędy i niedopatrzenia.
Z myślą o śmiałym używaniu drewna w konstrukcjach drewnianych przygotowaliśmy niniejsze opracowanie, w którym krok po kroku (od bazy surowcowej poprzez przerób po materiały finalne) przedstawiliśmy szereg istotnych i przekrojowych zagadnień z zakresu inżynierii materiałów drzewnych, stawiając szczególny nacisk na problematykę produkcji i sortowania tarcicy konstrukcyjnej. Znalazły się tu informacje zarówno z zakresu budowy, wad i właściwości drewna jak i uregulowań normalizacyjnych, a także przegląd technik przetarcia i analiza działania maszyn sortowniczych.