scholarly journals Selected Properties of Cement Bound Spruce and Larch Bark Bio-Aggregates

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4438
Author(s):  
Johannes Urstöger ◽  
Marius Cătălin Barbu ◽  
Thomas Pacher ◽  
Alexander Petutschnigg ◽  
Johannes Jorda ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Composite Material ◽  
Picea Abies ◽  
Larix Decidua ◽  
Tree Bark ◽  
Temperature Profiles ◽  
Spruce Bark ◽  
Bonded Composite ◽  
Similar Range

The aim of this study is to investigate the suitability of spruce and larch bark for the production of cement-bonded composites. At the beginning of this research, the curing behaviour of the admixtures was quantified with temperature profiles when testing spruce, larch, pine and poplar bark, to determine the compatibility between the components of the bio-aggregates, to analyse the cement curing and to establish which bark species should be successfully included in cement bonded composites. Considering the results, it was observed that the average densities of 600–700 kg/m3 of bio-aggregates are 40–55% lower than that of established products on the market, although spruce and larch bark are in a similar range. The situation is different for the compressive strength, as larch bark showed up to 30% higher values than spruce bark. This study revealed also different hardening characteristics of the two cement types used as binders for spruce and larch bark. The results of this study demonstrated that tree bark of Picea abies and Larix decidua Mill. can be successfully utilized for the production of a cement-bonded composite material.

scholarly journals Impact Of Pine (Pinus sylvestris L.) And Spruce (Picea abies (L.) Karst.) Bark Extracts On Important Strawberry Pathogens

2015 ◽  
Vol 69 (1-2) ◽  
pp. 62-67 ◽  
Author(s):  
Sandra Minova ◽  
Rita Sešķēna ◽  
Santa Voitkāne ◽  
Zane Metla ◽  
Māris Daugavietis ◽  
...  
Keyword(s):  
Picea Abies ◽  
Pinus Sylvestris ◽  
Phytopathogenic Fungi ◽  
Tree Bark ◽  
Colletotrichum Acutatum ◽  
Economic Losses ◽  
Spruce Bark ◽  
Ethanol Extracts ◽  
Mycosphaerella Fragariae

AbstractPhytopathogenic fungi induced considerable economic losses in strawberry production industry; therefore, more attention should be paid to development and implementation of preventative treatment that is environmentally friendly. Coniferous trees produce a wide variety of compounds, such as terpenoids and phenolics. Several studies are known on fungicidal activity of different components of coniferous tree bark. The aim of this study was to evaluatein vitropine (Pinus sylvestrisL.) and spruce (Picea abies(L.) Karst.) bark ethanol extracts impact on pathogenous fungi causing diseases of strawberries. Products of processed pine (Pinus sylvestris) and spruce (Picea abies) bark were tested. During 2011 to 2013, severalin vitroexperiments were carried out to test the effectiveness of pine and spruce bark extracts against various phytopathogenic fungi isolated from strawberries:Botrytis cinerea, Colletotrichum acutatum, Phytophthora cactorumandMycosphaerella fragariae.Radial growth tests showed that coniferous bark extracts inhibit mycelial growth ofB. cinerea, C. acutatum, P. cactorumandM. fragariae. Extracts had the highest antifungal effect onB. cinereatwo and five days after inoculation (p< 0.05). Bark extracts can reduce the sporulation ofB. cinerea, C. acutatumandP. cactorum.

scholarly journals Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

2016 ◽  
Vol 13 (5) ◽  
pp. 1537-1552 ◽  
Author(s):  
Marta Petrillo ◽  
Paolo Cherubini ◽  
Giulia Fravolini ◽  
Marco Marchetti ◽  
Judith Ascher-Jenull ◽  
...  
Keyword(s):  
Picea Abies ◽  
Decay Rate ◽  
Norway Spruce ◽  
Matrix Model ◽  
Rate Constants ◽  
Radiocarbon Dating ◽  
Time Lag ◽  
Larix Decidua ◽  
European Larch ◽  
14C Dating

Abstract. Due to the large size (e.g. sections of tree trunks) and highly heterogeneous spatial distribution of deadwood, the timescales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the chronosequence approach and the five-decay class system that is based on a macromorphological assessment. For the decay classes 1–3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) radiocarbon dating was used. In addition, density, cellulose, and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model, a regression approach, and the stage-based matrix model. In the decay classes 1–3, the ages of the CWD were similar and varied between 1 and 54 years for spruce and 3 and 40 years for larch, with no significant differences between the classes; classes 1–3 are therefore not indicative of deadwood age. This seems to be due to a time lag between the death of a standing tree and its contact with the soil. We found distinct tree-species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were estimated to be in the range 0.018 to 0.022 y−1 for spruce and to about 0.012 y−1 for larch. Snapshot sampling (chronosequences) may overestimate the age and mean residence time of CWD. No sampling bias was, however, detectable using the stage-based matrix model. Cellulose and lignin time trends could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 years for spruce and 50 years for larch. The half-life of lignin is considerably higher and may be more than 100 years in larch CWD. Consequently, the decay of Picea abies and Larix decidua is very low. Several uncertainties, however, remain: 14C dating of CWD from decay classes 4 and 5 and having a pre-bomb age is often difficult (large age range due to methodological constraints) and fall rates of both European larch and Norway spruce are missing.

scholarly journals How Bark Beetle Attack Changes the Tensile and Compressive Strength of Spruce Wood (Picea abies (L.) H. Karst.)

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 87
Author(s):  
Radim Löwe ◽  
Miroslav Sedlecký ◽  
Adam Sikora ◽  
Anna Prokůpková ◽  
Roman Modlinger ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Picea Abies ◽  
Bark Beetle ◽  
Reference Group ◽  
Ct Scanning ◽  
The Czech Republic ◽  
Central European ◽  
Spruce Wood ◽  
Mechanical And Physical Properties ◽  
Individual Trees

Since 2014, forestry in the Czech Republic has been significantly affected by a bark beetle outbreak. The volume of infested trees has exceeded processing capacity and dead standing spruce (Picea abies) remain in the forest stands, even for several years. What should be done with this bark beetle wood? Is it necessary to harvest it in order to preserve the basic mechanical and physical properties? Is it possible to store it under standard conditions, or what happens to it when it is “stored” upright in the forest? These are issues that interested forest owners when wood prices were falling to a minimum (i.e., in 2018–2019) but also today, when the prices of quality wood in Central European conditions are rising sharply. To answer these questions, we found out how some of the mechanical properties of wood change in dead, bark beetle-infested trees. Five groups of spruce wood were harvested. Each of these groups was left upright in the forest for a specified period of time after bark beetle infestation, and one group was classified as a reference group (uninfested trees). Subsequently, we discovered what changes occurred in tensile and compressive strength depending on the time left in the stand and the distance from the center of the trunk. When selecting samples, we eliminated differences between individual trees using a CT scanning technique, which allowed us to separate samples, especially with different widths of annual rings and other variations that were not caused by bark beetle. The results showed the effect of log age and radial position in the trunk on tensile and compressive strength. The values for tensile strength in 3-year infested trees decreased compared to uninfested trees by 14% (from 93.815 MPa to 80.709 MPa); the values for compressive strength then decreased between the same samples by up to 25.6% (from 46.144 MPa to 34.318 MPa). A significant decrease in values for compressive strength was observed in the edges of the trunks, with 44.332 MPa measured in uninfested trees and only 29.750 MPa in 3-year infested trees (a decrease of 32.9%). The results suggest that the use of central timber from bark beetle-infested trees without the presence of moulds and fungi should not be problematic for construction purposes.

EFFECT OF CHEMICAL TREATMENTS ON THE GERMINATION OF FOREST TREE SEEDS

1946 ◽  
Vol 22 (1) ◽  
pp. 17-24 ◽  
Author(s):  
L. P. V. Johnson
Keyword(s):  
Picea Abies ◽  
Copper Oxide ◽  
Picea Glauca ◽  
Pinus Resinosa ◽  
Forest Tree ◽  
Potassium Nitrate ◽  
Larix Decidua ◽  
Fraxinus Excelsior ◽  
Betula Papyrifera ◽  
Betula Lenta

Chemical treatments were tested, in comparison with stratification and presoaking, for their effects on germination of forest tree seeds.Significant increases in percentage germination were obtained from potassium nitrate in Betula lenta, B. papyrifera, Fraxinus excelsior, Picea Abies, P. glauca, P. rubens and Pinus resinosa; from thiourea in Larix decidua, Picea Abies, P. glauca and P. rubens; from ethylene chlorhydrin in Betula lenta, B. papyrifera, Fraxinus excelsior, Larix decidua and Pinus resinosa; from red copper oxide in Pinus resinosa; from zinc oxide in Betula papyrifera, Picea glauca, Pinus Banksiana and P. resinosa; from stratifiaction in Acer saccharum, Betula lenta, B. lutea, B. papyrifera, B. populifolia, Fraxinus excelsior, Larix decidua, Picea glauca, Pinus resinosa and P. Strobus; and from presoaking in Betula papyrifera, Larix decidua and Picea Abies.The rate of germination was accelerated by potassium nitrate in Betula papyrifera, Picea Abies, P. glauca, P. rubens and Pinus Strobus; by thiourea in Betula lenta, Larix decidua, Picea glauca and P. rubens; by ethylene chlorhydrin in Larix decidua; by red copper oxide in Betula papyrifera; by stratification in practically all species; and by presoaking in Larix decidua and Picea Abies.The rate of seedling growth was increased by zinc oxide in Larix, Picea, Pinus and Thuja, and by red copper oxide in Pinus.

Influence of the Method of Polymerization of Composite Material for Teeth Crown Fillings on its Strength Properties

2015 ◽  
Vol 240 ◽  
pp. 168-173
Author(s):  
Grzegorz Milewski ◽  
Tomasz Majewski
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Composite Material ◽  
Modulus Of Elasticity ◽  
Strength Properties ◽  
Dental Practice ◽  
Polymerization Shrinkage ◽  
Filling Materials

Polymerization shrinkage of composite filling materials still becomes one of the most important features which decreases strength properties of reconstructed teeth crowns. From among various methods to reduce that disadvantageous phenomenon which are used in a dental practice sandwich filling processing of crown cavity seems to be the most effective one. The paper presents the results of the strength examination of the influence of the different ways of layered polymerization processing on the mechanical properties of modern hybrid micro composite material with regards to the following quantities: compressive strength, strain to fracture, modulus of elasticity and work to fracture.

scholarly journals Merocoenoses of cambioxylophagous insect fauna of Norway spruce (Picea abies [L.] Karst.) with focus on bark beetles (Coleoptera: Scolytidae) and types of tree damage in different gradation conditions

2010 ◽  
Vol 56 (No. 10) ◽  
pp. 474-484 ◽  
Author(s):  
E. Kula ◽  
W. Ząbecki
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Bark Beetles ◽  
Fungal Pathogens ◽  
Ips Typographus ◽  
Insect Fauna ◽  
Spruce Bark ◽  
Standing Trees ◽  
Spruce Stands ◽  
Endemic Population

Research on merocoenoses of cambioxylophagous insect fauna of Norway spruce (Picea abies [L.] Karst.) was carried out in spruce stands of different age in the area with an endemic population (Moravian-Silesian Beskids, Czech Republic) and in the area with an epidemic population (Beskid Żywiecki, Poland) of the eight-toothed spruce bark beetle Ips typographus (L.). The structure of merocoenoses was characterized separately for standing trees attacked by bark beetles, trees struck by lightning, trees affected by fungal pathogens and wind-felling and trees in the form of snags and fragments. The occurrence of cambioxylophagous insects, mostly bark beetles (Coleoptera: Scolytidae), was compared between the study areas with emphasis on dominant facultative primary bark beetles and types of damage to spruce trees. &nbsp;

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