scholarly journals Properties of Oak Roundwood with and without Frost Cracks

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 538
Author(s):  
Przemysław Mania ◽  
Arkadiusz Tomczak
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Wood Quality ◽  
Frost Damage ◽  
Quercus Petraea ◽  
Modulus Of Rupture ◽  
Mechanical Parameters ◽  
Entire Volume ◽  
Oak Wood ◽  
Tangential Directions

The aim of this study was to examine certain properties of sessile oak wood (Quercus petraea (Matt.) Liebl.) with frost cracks, such as density (ρ), modulus of rupture (MOR), modulus of elasticity (MOE), and compressive strength in all anatomical directions and to compare it with control trees without frost cracks. Oak with frost cracks had a higher wood density (ρ = 765 kg × m−3) than the control (ρ = 650 kg × m−3). However, despite its lower density, the control oak was characterized by noticeably better mechanical parameters, with the exception of the compressive strength in radial and tangential directions. Differences in mechanical parameters reached up to 26%. The tests were performed on wood taken from trees with frost cracks that formed over 10 years to several decades ago. Frost cracks can render wood vulnerable to fungi growth, which leads to rotting and discoloration. Differences in strength were found on samples with no visible signs of decay, as they were cut at a distance from the crack. Nonetheless, the observed differences in strength allowed us to conclude that the shreds of fungi, as well as decay, may occur in the entire volume of the frost-damaged log. Such wood is, therefore, of a lower quality than that made of logs without any frost damage. Trees with frost cracks should be progressively be felled during the periodic intermediate cutting, as their wood quality may systematically deteriorate over the years.

scholarly journals Impact of cyclic densification on bending strength and modulus of elasticity of wood from temperate and tropical zones

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2869-2881
Author(s):  
Agnieszka Laskowska
Keyword(s):  
Modulus Of Elasticity ◽  
Mechanical Treatment ◽  
Bending Strength ◽  
Negative Impact ◽  
Modulus Of Rupture ◽  
Oak Wood ◽  
Densification Temperature ◽  
Before And After ◽  
Thermo Mechanical Treatment ◽  
Milicia Excelsa

Oak (Quercus robur L.), iroko (Milicia excelsa (Welw.) C.C. Berg), and tauari (Couratari spp.) wood were subjected to cyclic thermo-mechanical treatment (CTMT). The densification temperature amounted to 100 °C or 150 °C. The greatest changes in the modulus of rupture (MOR) value of the iroko wood, depending on the number of thermo-mechanical modification cycles, were noted. The MOR of the iroko wood, densified at 100 °C or 150 °C, after second thermo-mechanical modification cycle was twice as high as before the modification. No significant differences were observed between the modulus of elasticity (MOE) of oak wood before and after one modification cycle. Similar dependencies were noted in iroko wood. The thermo-mechanical modification performed over two cycles led to the highest increase, by about 56%, in MOE in oak wood densified at 150 °C. It was demonstrated that modification at 150 °C had a negative impact on iroko wood, which was manifested in the lower compression ratio of iroko at 150 °C than at 100 °C.

scholarly journals Effects of epyxilous fungus Laetiporus sulphureus (Bull. ex Fr.) murrill on the deccomposition of oak wood

2017 ◽  
pp. 21-30
Author(s):  
Miroslava Marković ◽  
Snežana Rajković ◽  
Mara Tabaković-Tošić ◽  
Marija Milosavljević
Keyword(s):  
Regression Line ◽  
Brown Rot ◽  
Wood Properties ◽  
Quercus Petraea ◽  
Modulus Of Rupture ◽  
Oak Wood ◽  
Brown Rot Fungi ◽  
Static Modulus ◽  
Laetiporus Sulphureus ◽  
The Impact

Testing samples were collected from the medulla of healthy oak trees in Eastern Serbia, from the association of Quercetum montanum. Over the periods of 2, 4 and 6 months the wood samples were exposed to influence of the mycelia of the fungus causing cubical brown rot on oak. Given that static modulus of rupture provides the quickest and clearest way to observe destruction caused by epixylous fungi, this paper researched the decrease in modulus of rupture of Sessile oak wood due to influence of causers of cubical brown rot. The samples have been exposed to the impact of the mycelia of the brown rot fungus on oak tree Laetiporus sulphureus (Bull. ex Fr.) Murrill (Sulphur Polypore). Effect of to the impact of the brown rot fungi was investigated, in decrease of static modulus of rupture Quercus petraea agg. The static modulus of rupture caused by L. sulphureus after 2, 4 and 6 months decreased in comparison with initial ones (100%) and reached 91.73, 75.17 and 63.25%. By using correlation analyses of Q. petraea agg. static modulus of rupture - ss (dependent variable) of fungi time influence (T-independent variable) strong correlation between variables was established, and regression equation is: ss= 151.514 ± 30,657 √ T The regression line obtained through data processing opened the possibility to prognosticate the changes of wood properties in certain time periods of the effect of the fungus under the unchanged external conditions, which is significant for practical purposes in terms of taking protective measures and wood usability.

scholarly journals Effects of Hybrid Polypropylene-Steel Fiber Addition on Some Hardened Properties of Lightweight Concrete with Pumice Breccia Aggregate

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Slamet Widodo ◽  
Iman Satyarno ◽  
Sri Tudjono
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Splitting Tensile Strength ◽  
Modulus Of Rupture ◽  
Hybrid Fiber ◽  
Hardened Properties ◽  
Fiber Addition

Lightweight concrete application in construction field is growing rapidly in these recent years due to its advantages over ordinary concrete. In this paper, pumice breccia which can be found abundantly in Indonesia is proposed to be utilized as the coarse aggregate. In spite of its benefits, lightweight concrete exhibits more brittle characteristics and lower tensile strength compared with normal concrete. On the other hand, fiber addition into concrete has become widely used to improve its tensile properties. Furthermore, the utilization of hybrid fiber in a suitable combination may potentially improve the mechanical properties of concrete. This paper experimentally examines the effects of hybrid polypropylene-steel fiber addition on some hardened properties of pumice breccia aggregate lightweight concrete. Five groups of test specimens with fixed volume fraction of polypropylene fiber combined with different amounts of steel fiber were added in concrete to investigate the density, compressive strength, modulus of elasticity, splitting tensile strength, and the modulus of rupture of the concrete mixtures. Test results indicate that hybrid fiber addition leads to significant improvement to the compressive strength, modulus of elasticity, splitting tensile strength, and the modulus of rupture of the pumice breccia lightweight aggregate concrete and meet the specification for structural purposes.

Physical and Mechanical Properties of Alnus Formosana Wood Introduced into Sichuan

2014 ◽  
Vol 574 ◽  
pp. 411-415
Author(s):  
Ming Chen ◽  
Jian Hua Lyu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Impact Toughness ◽  
Modulus Of Elasticity ◽  
Basic Density ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Dry Density ◽  
Average Value ◽  
Mechanical And Physical Properties

The mechanical and physical properties of Alnus formosana wood from Sichuan, China were studied. Air-dry density, oven-dry density, basic density, shrinkage, swelling, parallel-to-grain compressive strength, parallel-to-grain tensile strength, modulus of rupture (MOR),modulus of elasticity (MOE) ,impact toughness were analyzed. Results from this study show that air-dry density, oven-dry density and basic density were respectively 0.52, 0.49 and 0.43g/cm3. The average value of volumetric shrinkage was 7.111% and the average value of volumetric swelling was 7.06%. The average values of modulus of elasticity (MOE) ,modulus of rupture (MOR), parallel-to-grain compressive strength, parallel-to-grain tensile strength and impact toughness were 8102.429 Mpa, 80.429 Mpa, 41.575Mpa, 81.542 Mpa and 47.406 Kj/m2 , respectively. This study solved a basic problem about the planting and utilization of Alnus formosana wood in Sichuan, China.

scholarly journals The Mechanics Properties of Self-Compacting Concrete Using Red-Tile Waste as Substitution of Fine Aggregates

2017 ◽  
Vol 23 (2) ◽  
pp. 149
Author(s):  
Crezensia Alfiora Deadema Dias Octobenita ◽  
Ade Lisantono
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Maximum Modulus ◽  
Modulus Of Rupture ◽  
Experimental Program ◽  
Self Compacting Concrete ◽  
Fine Aggregates ◽  
Maximum Compressive Strength

This paper presents the experimental program about the mechanics properties of Self-Compacting Concrete (SCC) using red-tile waste as substitution of fine aggregates. The proportion of red-tile waste substitution was 10 %; 20 %; 30; 40 %; and 50 % of fine aggregates by weight. Viscocrete-10 was used to maintain the workability and flowability of SCC. 72 cylinder specimens with the size of (150×300) mm and 18 beam specimens with the size of (100×100×500) mm were cast and tested in this study. The mechanics properties of SCC that were studied in this research were compressive strength, modulus of elasticity, and modulus of rupture. The compressive strength of SCC was tested at age 7; 14; and 28 days. While the modulus of elasticity and modulus of rupture of SCC were tested only at age 28 days. The result shows that the maximum compressive strength of SCC was obtained using red-tile waste with the proportion of 50 % as substitution of fine aggregates. The compressive strength of SCC using red-tile with the proportion of 50 % at age 7; 14; and 28 days were 64.746 MPa;, 65.564 MPa; and 71.940 MPa, respectively. While the maximum modulus of elasticity and modulus of rupture of SCC were obtained using red-tile with the proportion 50 % at age 28 days, and the modulus elasticity and modulus of rupture were 25863.192 MPa and 7.076 MPa, respectively.

scholarly journals Synthesis, Characterization and Mechanical Evaluation of the Phenol-Formaldehyde Composites

2008 ◽  
Vol 5 (s1) ◽  
pp. S1015-S1020 ◽  
Author(s):  
B. S. Kaith ◽  
Aashish Chauhan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Wear Resistance ◽  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Phenol Formaldehyde ◽  
Phenol Formaldehyde Resin ◽  
Modulus Of Rupture ◽  
Formaldehyde Resin ◽  
Physico Chemical

Phenol: formaldehyde ratio was varied in the synthesis of phenol- formaldehyde resin and used to prepare the composites. These composites were then evaluated for their mechanical strength on the basis of tensile strength, compressive strength and wear resistance. Composite with better strength was characterized by IR, SEM, XRD, TGA/DTA and further studies were carried out for its physico-chemical and mechanical properties like viscosity, modulus of rupture (MOR), modulus of elasticity (MOE) and stress at the limit of proportionality (SP)etc.

scholarly journals DEVELOPMENT OF CHICKEN FEATHER REINFORCED INSULATION PAPERBOARD FROM WASTE CARTON AND PORTLAND CEMENT

2019 ◽  
Vol 16 (1) ◽  
pp. 44
Author(s):  
Odusote Jamiu Kolawole ◽  
Dosunmu Kayode Stephen
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Modulus Of Elasticity ◽  
Cement Content ◽  
Modulus Of Rupture ◽  
Chicken Feather ◽  
Thickness Swelling ◽  
Chicken Feathers

Cartons and chicken feathers are common wastes which we need to dispose in one way or another. Disposal problems associated with these wastes can be solved by processing them into useful products such as insulation and ceiling boards. In this study, chicken feather reinforced ceiling board was developed from waste carton and Portland cement. The quantity of the chicken feather was kept constant at 10% based on previous findings, while the cement and waste carton contents were varied to produce 5 samples of different compositions. The density of the board was found to range between 337.8 and 700.7 kg/m2, while the thickness swelling ranges between 0.81 and 9.02%. Water absorption values of the samples varied between 7.16 and 24.41%, while the compressive strength and modulus of elasticity values varied from 4.8 - 10.3 N/mm2 and 1.03 - 1.60 GPa, respectively. The values of modulus of rupture ranges between 1.34 and 2.2 MPa while the thermal conductivity of the samples ranges from 0.951 to 1.077 W/m.K. Density, compressive strength, modulus of elasticity, modulus of rupture and thermal conductivity of the samples increased as the cement content increased, while the thickness swelling and water absorption decreased with increase in cement content. The results revealed that the properties of ceiling boards developed from 80% cement, 10% carton and 10% chicken feather can compete favorably with most ceiling boards available in the market.

scholarly journals EFFECT OF USING SLURRY INFILTRATED FIBER CONCRETE ON THE BEHAVIOR OF REINFORCED CONCRETE CORBELS

2021 ◽  
Vol 25 (Special) ◽  
pp. 4-69-4-77
Author(s):  
Hajer K. Alqaraghouly ◽  
◽  
Nibras N. Abdul-Hameed ◽  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Modulus Of Elasticity ◽  
Steel Fiber ◽  
Modulus Of Rupture ◽  
Vertical Load ◽  
Fiber Volume ◽  
Fiber Concrete

This paper experimentally presents the behavior and strength of slurry infiltrated fiber concrete (SIFCON) corbels. The program included 3 specimens in which steel fiber volume fractions were varied (6,8, and 10) %. All specimens had a constant shear span to depth ratio (a/d=0.7) and were of the same width, length, and thickness. The corbel specimens were examined under the effect of concentrated vertical load only. It was found that the compressive strength, splitting tensile strength, modulus of rupture, modulus of elasticity, and failure mode were improved with the increase in steel fiber content for all SIFCON corbels.

scholarly journals Draining cement concrete for hydrotechnical, road and airport сonstruction

2021 ◽  
pp. 88-102
Author(s):  
Igor Gameliak ◽  
◽  
Anzori Shurgaya ◽  
Yaroslav Yakimenko ◽  
Andrii Mysko ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Water Permeability ◽  
Modulus Of Elasticity ◽  
Hydraulic Structures ◽  
Mechanical Parameters ◽  
Cement Concrete ◽  
Environmental Friendliness ◽  
Drainage Capacity ◽  
Selection Of

The article is devoted to the selection of the composition of the cement-concrete mixture and the determination of physical and mechanical parameters of the draining cement concrete for the arrangement of the pavement of footpaths, parking lots and hydraulic structures with high drainage capacity. The object of research is the processes of composition design and ensuring the strength and capacity of draining cement concrete. The aim of the work is to select the composition and determine the physical and mechanical (compressive strength, tensile bending, deformable (modulus of elasticity), operational (abrasion), frost resistance, water permeability of draining cement concrete. Research methods - scientific and experimental. The results of the article can be used in the operation of road and airfield pavements in the culverts and foundations to improve the environmental friendliness of cities.

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