Understanding Wood: Properties, Defects, and Chilean Species
WOOD
Introduction: comes from trees, which are natural elements are therefore organic wood as raw material for man is subject to climatic variations is therefore to different consistency, density and thickness
Veins and structure
The veins correspond to the drawings showing all varieties of wood and keep a relationship or n with its own structure.
est timber to you ñ formed by small tubes that carry water and dissolved minerals in them from the t ra ces to the leaves. These vessels est á n drivers arranged vertically on the trunk. When we cut a tree in parallel to the axis of the wood has straight grain, but in some trees to the drivers est á n arranged in a spiral, that is wound around the axis of the trunk.
Cambium
In temperate areas the growth is not constant. The wood produced by the cambium in the spring and summer is more porous and lighter in color than that produced in winter. Thus, the tree trunk is composed of a pair of concentric rings new every year, one lighter than the other. Why they are called annual rings.
Growth, decay and decomposition
Over the years, trees are becoming increasingly high and bulky, not easy to cope with the process considering that wood is a solid material that can not be extended without breaking. The cambium is the tissue that allows the growth in thickness of stems and branches and is a thin layer of living cells that are forming a ring. As stated at the outset this structure produces two types of cells that form conductive tubes, xylem and phloem inward out. The xylem conducts wise gross (water, salts and minerals) to the leaves, while the phloem distributes the wise prepared (water, food starches and other substances) from the leaves to the rest of the individual. When phloem cells reach the surface, forming a crust die
Other information data the trees to have solved the weight problem of his own wood through the forms adopted in support types, allowing them to absorb and compensate for high growth.
its thickness is not always with the same intensity, depending on the species and climate conditions policies. Its annual growth in thickness is observed in so-called growth rings to see a stump
The time indicator rings
The growth rings of trees are superimposed to each other. Then you can determine its age by looking at a log in cutting the number of its rings and its width depending on whether the little é growth was favorable or unfavorable
Stages are distinguished in the cycle to trees
_Etapa Development
_Fase Equilibrium
_Descomposici Or No
Stage of development is generally the m to s long and during the tree to grow evenly and increase the wood produced. At the end of growth cycle is m s to slow and stop mass increase, bringing the tree to enter a second stage or phase.
Equilibrium phase
Ng can last many years. Renewing annual growth losses, otherwise, with increasing age and increasing losses, is to eliminate s I am a wood (as a result of fen or less of decomposition or n) that can be replaced.
thus the tree to rot and hollow inside, then multiply fungi penetrate and destroy the wood of the trunk.
No decomposition or final stage is the mineral that the tree he has met along his life begin to break free, contributing to the formation or n dehumus
Some trees in the forest to Chile
Araucaria
Scienti fic name is Araucaria araucana. It grows in the mountains, including volcanoes and Ian Antuco t n. Alsoé n you can find in the mountains of Nahuelbuta.
ICRP é s of guaitecas
Cient name is Pilgerodendron uvifera fic. Valdivia grows from ground fire and is especially on the islands of the province of Chiloe, Aisen and Magallanes
Cipro é s of the range
Scienti fic Name Austrocedrus chilensis. Grows between the Rio Maipo and Rio Palena, mainly in the foothills of the Andes mountains and the coast.
Man i o
are three species which are known coln this name: saxegothea conspicua, Podocarpus saligna nubigena podocarpus. Bosrques grow in the south and its wood is highly prized.
Oak
His name is scienti fic Nothofagus obliqua. Grows between Curic or y Puerto Montt.
Raul í
Scienti fic name is nothofogus alpina. It grows in the Andes Mountains, from or to Valdivia Curic.
Í pathology and defects as wood
The wood can be defined in t é general Terms, as commercially important as a hard and durable substance that forms the trunks of the trees to and has been used for thousands of years old pop as fuel and as building material or n.
Is a material that is familiar, but not high-tech í a, contributes to the manufacture of m or n ú multiple objects from home and in the construction or n for its great variety and beauty .. For strength and lightness prevails in many paí countries in the construction industry or taking a walk by n strove to enhance their properties and protect their weaknesses.
wood can be considered as a complex fiber reinforced composite material, consisting of long tubular cells rich polymorphic é, unidirectionally aligned in a polymorphic matrix rica. In addition to polymorphic s tubes est á n é rich compounds beam partially crystalline cellulose fibers, aligned to various angles relative to the axes of the tubes
The wood is composed of four main components:
Cellulose fibers, representing approximately 40% to 50% of the wood.
Cellulose:
It is a natural thermoplastic polymer with a degree of polymerization of about 10,000.
The extracts are organic impurities such as oils, which provide color to the wood or that act as preservatives against the environment and insects.
Inorganic minerals such as silica, which cause deterioration of saw blades or axes when sawing wood.
Fibrous structure, the basic component of wood is cellulose polymer chains configured to form long fibers. Much of each fiber is in the crystalline state, the crystalline regions are separated by small stretches of amorphous cellulose.
Cell structure:
the tree is composed of elongated cells often have a relationship so 100 or more and constitute approximately 95% of solid material in the timber.
The empty cells are formed by several layers constructed from micro fibrils. The first wall of the cell contains randomly oriented micro-fibrils. As thickened cell wall, are formed three distinct layers.
Both external and internal walls contain micro-fibrils oriented in two directions that are parallel to the cell
WOOD PROPERTIES
MOISTURE
The wood contains water of constitution, inert organic nature, water saturation, which permeates the walls of woody elements and free water absorbed by capillary vessels and tracheids. (Type xylem conducting cells that circulate crude sap) the humidity of the wood can be seen, besides the heavy procedure, specimens, and wet and dried colorimetric, by electrical conductivity, using electric gyrometers.
These variations in humidity cause wood to swell or shrink, changing its volume and therefore its density.
DENSITY
The actual density of the wood is approximately equal for all species, about 1.56. Kg / dm 3 bulk density varies not only from one species to another, but still the same with the moisture content and tree and site to find the average density of a tree must be removed specimens of samples at several sites.
As the apparent density of a timber includes the volume of voids and clumps, the higher the bulk density of wood, the greater the surface of the resistive elements and the smaller the pores of
Shrinkage and swelling
L change the volume of wood as the moisture content. When you lose or drop water contracts, to be minimal in the axial direction or the fibers that comprise it. Is no more than 0.8%, from 1% to 7.8% radial and 5% to 11.5% in the tangential.
The contraction is greater in sapwood than in the heart, causing tensions desiccation crack and warp the wood.
The swelling occurs when it absorbs moisture. Submerged wood volume increases little axial or fiber and 2.5% to 6%. Perpendicular, but the increase in weight ranges from 50% to 150%.
The timber volume increases to the point of saturation (20% to 25% water) and leave it no more volume increases, while still absorbing water.
We must take these changes in the volume of parts that are to be subjected to fluctuations of dryness and moisture, allowing the necessary space for the push to occur without compromising the stability of the work.
Hendibilidad
é n also called the crack easily and the ability of wood to split in the longitudinal direction under the action or a cu n ñ a.
the splitting is more easy to f in the direction of the spokes. Wood very hendible as is customary to cite the caste ñ or, as hendible wood, oak wood and as little hendible, hornbeam.
Conductivity
dry wood is a bad conductor of heat and electricity, as no t when wet. Conductivity is greater in longitudinal than in the radial or transverse mto s in heavy timber in the light and porous, which are used as insulators t é rmico on pavements and walls.
Dilation or NT and rmic
dilation coefficient of linear or n is very small timber ñ or can be neglected.
Duration or No
Wood is by its nature a very durable suistancia. If not attack living organisms, can be kept hundreds or even thousands of years old pop.
have found remains of wood used by the Romans nearly intact thanks to a combination of circumstances or n that have been protected from external attacks.
organisms that attack wood, m to s important is a fungus that causes desacemiento called the ra t z, s or what happens when wood est to h ú meda.
WOOD DEFECTS OR PATHOLOGIST Í A WOOD
Í defects are anomalies as modifying the structure of wood and alterations are diseases that affect their composition or n qu í mica and reduce their resistance.
to continuation or No defects referred to s m common.
Defects and wood diseases
It is considered as defects of the wood, all abnormalities of the structures, textures and color prejudice or n. Its use
The defects may have the wood may have an origin in t:
a. – deformation of fibrous structure during growth of the tree to
b. – infections due to parasitic diseases, insect attacks and vertebrates.