Comparison of mechanical properties of recent and 400-year-old European larch

Wood is considered the leading building material throughout the history of mankind. Wood has several advantages over other construction materials, which also makes it one of the most promising materials of the future. The environmental aspect also plays a major role today, as wood is a natural, renewable resource whose processing is very energy-intensive. Due to its repeated and widespread use in construction, the prediction of mechanical properties and their change over time is also very well known, as the overall safety of all buildings also depends on it. Therefore, we compared the mechanical properties of fresh European larch (Larix decidua) and 400-year-old larch found in the Ruard manor house on the Stara Sava in Jesenice, where the renovation of Upper Sava Museum is currently underway. In order to predict what will happen to the wood in the long term, it is necessary to expose the wood to the same conditions, i.e. to change it with dynamic loads or material fatigue. The effect of aging on flexural strength has not been confirmed. Fatigue results show that old wood withstood about 18 times fewer load cycles than recent larch wood.

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Economics and evolution

The Paleontological Society Special Publications ◽

10.1017/s2475262200008583 ◽

1992 ◽

Vol 6 ◽

pp. 298-298

Author(s):

Geerat J. Vermeij

Keyword(s):

Energy Use ◽

Construction Materials ◽

Ripple Effect ◽

Use Of Resources ◽

Economic Interpretation ◽

History Of ◽

Long Term Trends ◽

Random Nature ◽

Antagonistic Interactions

Individual organisms compete for resources. Among competitive dominants, per-capita energy use has generally increased through time. This increase has had a ripple effect on all other species by increasing the number of competitive and predatory encounters among individuals. Species unable to cope with such biological rigors have become restricted to environments where resource supply is low and where encounters with enemies are few. Among species that hold their own in biologically rigorous habitats, construction materials that are cheap to produce and that enable individuals to grow and respond quickly have generally been favored over those that exact a high cost in energy and time. Extinction interrupts but does not reverse or fundamentally alter these long-term between-clade evolutionary trends. The availability of resources to organisms, as well as the opportunity for evolutionary change, depends on extrinsic events and factors as well as on the competitive abilities of organisms.Those who have raised methodological and theoretical objections against this economic interpretation of the history of life deny the overriding importance of organisms as agents of natural selection, emphasize the random nature of extinction, deny the existence of long-term trends, favor a larger role for mutualistic as opposed to antagonistic interactions, or accord a larger role to species-level attributes in evolution that are not reducible to the properties of individual organisms. These arguments are either unpersuasive or incorrect. The long-term economics of life may have important lessons for our own use of resources.

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Physico-Mechanical Properties and Long-Term Creep Behavior of Wood-Plastic Composites for Construction Materials: Effect of Water Immersion Times

Case Studies in Construction Materials ◽

10.1016/j.cscm.2021.e00791 ◽

2021 ◽

pp. e00791

Author(s):

Thanate Ratanawilai ◽

Chainarong Srivabut

Keyword(s):

Mechanical Properties ◽

Creep Behavior ◽

Water Immersion ◽

Construction Materials ◽

Wood Plastic Composites ◽

Effect Of Water ◽

Plastic Composites ◽

Term Creep

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Elastic Properties of Thermo-Hydro-Mechanically Modified Bamboo (Guadua angustifolia Kunth) Measured in Tension

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.600.111 ◽

2014 ◽

Vol 600 ◽

pp. 111-120 ◽

Cited By ~ 6

Author(s):

Hector Fabio Archila-Santos ◽

Martin Philip Ansell ◽

Peter Walker

Keyword(s):

Mechanical Properties ◽

High Performance ◽

Sheet Material ◽

Construction Materials ◽

Uniform Density ◽

Structural Applications ◽

Saturated Sample ◽

Prediction Of Mechanical Properties ◽

Water Saturated ◽

Poissons Ratio

Guadua angustifolia Kunth (Guadua) was subjected to thermo-hydro-mechanical (THM) treatments that modified its microstructure and mechanical properties. THM treatment was applied to Guadua with the aim of tackling the difficulties in the fabrication of standardised construction materials and to gain a uniform fibre density profile that facilitates prediction of mechanical properties for structural design. Dry and water saturated Guadua samples were subjected to THM treatment. A densified homogenous flat sheet material was obtained. Mechanical properties of small clear specimens of THM modified Guadua were evaluated by testing in tension and compared to the results of the same test on a control specimen. Samples were tested in the elastic range to determine values for Modulus of Elasticity (MOE) and Poissons ratio. There was a significant increase in the tensile MOE values (parallel to the direction of the fibres) for densified samples. MOE values measured were 16.21 GPa, 22.80 GPa and 31.04 GPa for control, densified dry and densified water saturated samples respectively. Oven dry densities for these samples were 0.54 g/cm3, 0.81 g/cm3 and 0.83 g/cm3. Despite a 50 % reduction in the radial Poissons ratio for the water saturated sample, no further variation in the Poissons ratio as a result of densification was observed for control and densified dry samples. This paper presents the results of the first phase of a study focussed on the manufacturing of flat Guadua sheet (FGS) by THM treatment and the characterization of its mechanical properties. The achievement of a dimensionally stable FGS by THM modification, with a uniform density and achieved with reduced labour effort during manufacture, will be of key importance for the development of structural applications, and could have a significant impact in the bamboo industry. The final aim of the research at the University of Bath is the development of Cross Laminated Guadua (CLG) panels using THM modified and laminated FGS glued with a high performance resin.

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Modeling and Optimization of Technology and Physics-Mechanical Properties of Composite Materials

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.864.59 ◽

2020 ◽

Vol 864 ◽

pp. 59-65

Author(s):

Larysa Trofimova

Keyword(s):

Mechanical Properties ◽

Composite Materials ◽

System Development ◽

Experimental Studies ◽

Construction Materials ◽

Stick Slip ◽

Structure Changes ◽

History Of ◽

Topological Models ◽

Practical Nature

To this day, there is a large volume collected of the results of experimental studies on structure changes in various dispersions serving as base for production of most construction materials. The analysis of collected information revealed that there is an entire category of stick-slip phenomena, the case history of which is represented by N-and S-type inflections on rheological, kinetic and other curves. We should emphasis that the view of such non-trivial charts is alike with geometry of standard curves of standard conditions. And this alikeness predetermines the possibility of applying topological models of «fold» and «ruffle» types for studying various abnormal effects. We must also note that besides N- and S-types there is a range of other characteristics («flags») pointing to applicability of the methods of catastrophe theory to studying certain processes initiating the apparition of interruptions in system development. Recognition of above-mentioned particularities allows determining the fact and type of catastrophe, the standardised structure of which facilitates finding strict patterns and thus defines directions of optimisation of various situations of research and practical nature. This work shows that pieces of evidence and consistent patters are reliably interpreted within the framework of the proposed concept.

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Enhancement of Waste Foundry Sand Mechanical Properties Through Stabilization Using Slag Based Geopolymer Binder

10.21203/rs.3.rs-366174/v1 ◽

2021 ◽

Author(s):

Thandiwe Sithole ◽

Tebogo Mashifana ◽

Nelson Tsotetsi

Keyword(s):

Mechanical Properties ◽

Construction Materials ◽

Foundry Sand ◽

Minimum Requirement ◽

Granulated Blast Furnace Slag ◽

Waste Foundry Sand ◽

Materials Used ◽

Corrosive Environments ◽

Geopolymer Binder

Abstract It is of paramount importance to minimize carbon emission generated from production of major building and construction materials used worldwide such as bricks and Ordinary Portland cement to achieve sustainability requirements. In this paper, the binding properties of the synthesized granulated blast furnace slag (GBFS) geopolymers were assessed by developing eco-friendly waste foundry sand bricks. Four different mix designs were prepared by blending GBFS based geopolymer binder with aggregates (waste foundry sand and crushed stones). The amount of GBFS geopolymer binder was varied from 0 to 40 %. The developed specimens were evaluated for mechanical properties, durability, structural performance, and environmental impact. The specimens synthesised with 40 % GBFS geopolymer binder at a L/ S ratio of 15 % and cured at 80 ℃ achieved the highest UCS of 12 MPa. The results showed that the developed specimens are acid resistant which suggest that they can be used in corrosive environments and do not pose any threat of environmental pollution for long-term use. In conclusion, GBFS-based geopolymers can be used as binders to fabricate building bricks that meet the minimum requirement of ASTM C62-10 that can be used in negligible weathering conditions.

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Atypical Femoral Fracture in McCune-Albright Syndrome

Journal of Research in Orthopedic Science ◽

10.32598/jrosj.7.3.711.1 ◽

2020 ◽

Vol 7 (3) ◽

pp. 147-152

Author(s):

Salman Ghaffari ◽

◽

Mehran Razavipour ◽

Parastoo Mohammad Amini ◽

◽

...

Keyword(s):

Femoral Fracture ◽

Dynamic Compression ◽

Plate Fixation ◽

Medullary Canal ◽

Mccune Albright Syndrome ◽

Café Au Lait Spots ◽

History Of ◽

Albright Syndrome ◽

Mccune Albright

McCune-Albright Syndrome (MAS) is characterized by endocrinopathies, café-au-lait spots, and fibrous dysplasia. Bisphosphonates are the most prescribed treatment for reducing the pain but their long-term use has been associated with atypical fractures of cortical bones like femur in patients. We present a 23-year-old girl diagnosed with MAS. She had an atypical mid-shaft left femoral fracture that happened during simple walking. She also had a history of long-term use of alendronate. Because of the narrow medullary canal, we used 14 holes hybrid locking plate for the lateral aspect of the thigh to fix the fracture and 5 holes dynamic compression plate (instead of the intramedullary nail) in the anterior surface to double fix it, reducing the probability of device failure. With double plate fixation and discontinuation of alendronate, the complete union was achieved five months after surgery

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Prediction of Mechanical Properties of Microalloyed Medium-Carbon Wire Rods and Bars

AISTech2019 Proceedings of the Iron and Steel Technology Conference ◽

10.33313/377/204 ◽

2019 ◽

Author(s):

L. Lima ◽

R. Lino ◽

J. Barbosa ◽

H. Ferreira ◽

E. Costa ◽

...

Keyword(s):

Mechanical Properties ◽

Medium Carbon ◽

Prediction Of Mechanical Properties

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European Integration

10.3366/edinburgh/9781474455893.001.0001 ◽

2020 ◽

Author(s):

Johann P. Arnason

Keyword(s):

European Integration ◽

Eastern European ◽

The European Union ◽

Historical Processes ◽

History Of ◽

External Conditions ◽

Eastern European Countries ◽

Totalitarian Regimes ◽

The Eu

Different understandings of European integration, its background and present problems are represented in this book, but they share an emphasis on historical processes, geopolitical dynamics and regional diversity. The introduction surveys approaches to the question of European continuities and discontinuities, before going on to an overview of chapters. The following three contributions deal with long-term perspectives, including the question of Europe as a civilisational entity, the civilisational crisis of the twentieth century, marked by wars and totalitarian regimes, and a comparison of the European Union with the Habsburg Empire, with particular emphasis on similar crisis symptoms. The next three chapters discuss various aspects and contexts of the present crisis. Reflections on the Brexit controversy throw light on a longer history of intra-Union rivalry, enduring disputes and changing external conditions. An analysis of efforts to strengthen the EU’s legal and constitutional framework, and of resistances to them, highlights the unfinished agenda of integration. A closer look at the much-disputed Islamic presence in Europe suggests that an interdependent radicalization of Islamism and the European extreme right is a major factor in current political developments. Three concluding chapters adopt specific regional perspectives. Central and Eastern European countries, especially Poland, are following a path that leads to conflicts with dominant orientations of the EU, but this also raises questions about Europe’s future. The record of Scandinavian policies in relation to Europe exemplifies more general problems faced by peripheral regions. Finally, growing dissonances and divergences within the EU may strengthen the case for Eurasian perspectives.

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