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- Wooden Houses of Anatolia
- Wood as a Edifice Cloth; It's Benefits and Disadvantages
Wood as a Building Material; It's Benefits and Disadvantages
Wooden Houses of Anatolia
Wood as a Edifice Material; It'south Benefits and Disadvantages
INTRODUCTION
For the long term durability of historical wooden buildings, constructors and users who deal with this subject have to know forest properties exactly.
Wood is an organic, hygroscopic and anisotropic material. Its thermal, acoustic, electrical, mechanical, aesthetic, working, etc. backdrop are very suitable to use information technology is possible to build a comfortable firm using only wooden products. With other materials, information technology is almost impossible. Merely wood has some disadvantages besides. Following is some very short information nigh this subject.
BENEFITS OF WOOD
Thermal Backdrop:
As we know, many, materials modify in size and book as the temperature changes. They aggrandize with increasing of the temperature. This ways linear and volumetric expansion. The expansion. The expansion causes decrease in the strength of materials. Steel, which is inorganic and not-combustible and therefore has an advantage against burn down, but when used in buildings, it expands and collapses as a upshot of increase in heat.
Wood does non practically aggrandize confronting heat. On the opposite, by the consequence of heat, it dries out and gains strength. The only time woods expands a little is when the humidity level is below 0%, and this is merely scientifically significant. In do, the humidity level of woods does non drop under v% even in the driest climate.
The coefficient of thermal conductivity of the wood is very depression. Aluminium transmits heat 7000 times, steal 1650 times, marble 90 times and drinking glass 23 times faster than wood. For this reason, forest is used for making matches, handles of hardware equipment, ceilings and wall coverings.
Specific estrus of wood is high. That means loftier amount of energy is needed to increase and decrease the temperature of ane-kilogram of wood. Wood requires nearly twice amount of heat energy than stones and concrete; similarly, 3 times of free energy is needed for heating or cooling steel.
Acoustic Properties:
Sound isolation is based on the mass of the surface. Wood, every bit a light fabric, is non very perfect for sound isolation; But it is platonic for sound assimilation. Wood prevents repeat and dissonance by absorbing sound. For this reason it is extensively used in concert halls.
Audio velocity is faster in woods than gases and liquids, and it is close to that of metals. Sound energy loss as a result of friction is likewise significantly depression in woods due to its lightness and structure. Considering of such backdrop, wood is extensively used in musical instruments.
Electric Properties:
Resistance to electrical current of a completely dry wood is equal to that of phenol formaldehyde. An oven stale forest is a very good electrical insulator. To some extent air dried wood is the same. Unfortunately electrical resistance of wood is lowered by increasing the moisture content. The resistance of wood saturated with h2o. Static electricity that is dangerous for human health is non observed in wood unlike metal, plastic and other materials. For this reason wood is preferred as a healthy material.
Mechanical Backdrop:
Although forest is a lite fabric, its strength is quite loftier. For instance, while the tensile forcefulness of wood with 0,6/cm3 specific gravity is 100 N/mm2, the tensile strength of steel with 7,89/cm3 specific gravity is 500 Due north/mm2. Dividing tensile force by specific gravity gives the breaking length and quality of material. This figure means the breaking length of the material, when hung as a effect of its own weight. While the breaking length of steel is used for construction is 5.iv km, chrome mobile steel is half-dozen.8 km, hardened bow steel is 17.5 km, breaking length of spruce woods is 19.8 km, and laminated wood made of beech is 28.three km. For this kind of backdrop, woods and laminated woods is used in wide-gap constructions like health centers and sport halls.
Aesthetic Properties:
Wood is a decorative cloth when considered as an aesthetic textile. Each tree has its own color, design and olfactory property the design of a tree does modify according to the mode it is sliced. It is possible to find dissimilar wooden materials according to colour and design preference. It can be painted to darker colors of varnished, and can exist given bright or mat touches.
Oxidation Properties:
Although woods has oxidation characteristics in some fashion, information technology is not the kind of oxidation seen in metals. Metals become rust, forest doesn't. For such characteristics, utilize of wood is preferred to avoid rust when necessary.
Working Properties:
Information technology is easy to repair and maintain wood. While one-time woods can be renewed by special touches other materials are highly hard and plush to maintain and to repair. Therefore they are ordinarily tending of.
Variation:
At that place are more than 5000 kinds of woods in the earth. Their specific gravity, macroscopic and microscopic structures are unlike. Accordingly, their concrete, thermal, acoustic, electrical and mechanical properties are too different. Because of this variety, it is possible to find forest suitable for needs. For example, for rut isolation and sound absorption woods in lightweight are used. Similarly, heavy ones are used for structure purposes.
DISADVANTAGES OF WOOD AND WAYS TO ELIMINATE THEM
There are some disadvantages of wood just they are easy to condone, and eliminate as long as the cause is known.
Shrinkage and Swelling of Forest:
Wood is a hygroscopic material. This ways that it will adsorb surrounding condensable vapors and loses moisture to air below the cobweb saturation signal.
Deterioration of Wood:
The agents causing the deterioration and destruction of wood fall into two categories: Biotic (biological) and abiotic (non-biological).
Biotic agents include decay and mold fungi, bacteria and insects.
Abiotic agents include sun, wind, water, certain chemicals and burn.
Biotic Deterioration of Wood:
Woods are organic goods. Like any organic expert, wood is a nutritional product for some plants and animals. Humans tin not digest cellulose and the other fiber ingredients of wood, but some fungi and insects tin digest information technology, and utilise it as a nutritional product. Insects drill holes and bulldoze lines into wood. Even more than dangerously, fungi crusade the forest to decay partially and even completely.
Biological deterioration of wood due to attack by disuse fungi, woodboring insects and marine borers during its processing and in service has technical and economical importance.
Fungi:
Information technology is necessary to give some short data about fungi agents to have measures confronting the wood deterioration.
Physiological requirements of wood destroying and wood inhabiting fungi:
A favorable temperature.
The temperature must exist 25-30°C for optimum growth of most forest rotting fungi. But some of them can tolerate temperature betwixt 0-45°C.
An adequate supply of oxygen
Oxygen is essential for the growth of fungi. In the absence of oxygen no fungi will grow. It is well known that storage of forest under water will protect them against attacks past fungi.
Moisture
By and large wood will not exist attacked by the common fungi at moisture contents beneath the cobweb saturation point. The fiber saturation point (FSP) for different wood lies between xx to 35% but 30% is accepted more often than not.
It is recommended that wood in service must have a moisture content at to the lowest degree 3% less than FSP to provide desirable rubber against fungi.
Nutrients
Woods is an organic chemical compound and consists of 50% carbon. That means that wood is a very suitable nutrient for fungi because fungi derive their free energy from oxidation of organic compounds. Disuse fungi wood rotters tin can use polysaccharides while stain fungi plainly require simple forms such as soluble carbohydrates, proteins and other substances present in the parenchyma prison cell of sapwood. Additionally, the presence of nitrogen in wood is necessary for the growth of fungi in wood.
Insects:
Insects are merely second to decay fungi in the economic loss they crusade to lumber and woods in service. Insects can be separated into four categories: Termites, powderpost beetles, carpenter ants and marine borers.
Termites
There are two types of termites: Subterranean termites impairment forest that is untreated, moist, in direct contact with continuing water, soil, other sources of moisture.
Dry out woods termites assail and inhabit wood that has been dried to wet contents every bit depression as 5 to 10%. The damage by dry wood termites is less than subterranean termites.
Powderpost beetles
Powderpost beetles set on hardwood and softwood. At risk is well seasoned woods every bit well equally freshly harvested and undried wood.
Carpenter ants
Carpenter ants exercise non feed on woods. They tunnel through the woods and create shelter. They attack most often woods in ground contact or wood that is intermittently wetted.
Carpenter bees
They cause damage primarily to unpainted wood by creating large tunnel in society to lay eggs.
Marine borers
They attack and can rapidly destroy wood in salt h2o and stagnant h2o.
Minimizing the Bug of Wood:
Almost of the commonly employed strategies for protecting woods involve drying, blanket and or impregnation.
Careful pick of wood
Some species have naturally decay resistant heartwood. Such species include sweet chestnut (Castanea sative Factory.), oak (Quercus spp.), juniper (Juniperus spp.). Sapwood is never naturally durable species has little or no decay resistance and must be treated if long-term durability is desired.
Coating
Coating provides protection to wood used both indoors and outdoors. Coating prevents rapid uptake and loss of moisture and reduces shrinking and swelling that tin can pb to surface bully and other problems. But coating does non totally prevent changes in moisture content. Coating slows, but does non halts moisture level. Coating with solid color or pigmented stains protects wood confronting ultraviolet rays.
The addition of fungicides to coating provides some protection confronting evolution of decay and mold fungi.
Deteriorating paint motion-picture show really increases the disuse take chances. Cracked paint allows moisture to come into contact with woods surface, and poses a bulwark to rapid and consummate redrying.
Drying
More often than not forest volition not be attacked by the mutual fungi at moisture content beneath the fiber saturation point (FSP). FSP for dissimilar wood prevarication between 20-35%, but 30% is accepted generally: Fungi can not set on wood used indoor and in heated rooms, since the equilibrium moisture content (EMC) is much more below than FSP. e.yard. 6%
If wood is soaked in water, wood absorbs h2o and is saturated with it. Finally at that place will exist no more oxygen in woods. In this situation fungi tin non grow in them. This is the main reason why woods are kept in water for a while. Besides underwater constructions, it is impossible to use woods completely wet; so when they are used out of water, they have to be completely dried out to EMC in order to protect them against fungi assault. In heated rooms, where the EMC lie between v-10%, fungi can not survive on them.
One of the well-nigh effective ways to prevent degradation of forest is to thoroughly dry information technology and go on it dry out. The concluding instance is very important since even wood that has been kiln dried will readily regain moisture if placed in a humid environment.
Wood can be dried in air or in some blazon of dry kiln. Air drying alone is not sufficient for wood items which are used in heated rooms. Therefore kiln drying is necessary. Kiln drying has many advantages: One of them is the killing of staining or woods destroying fungi or insects that may be attack the wood and lower its grade.
Forest that will exist used indoor need only exist dried to provide for long term protection against rot.
Treating With Wood Preservatives
We tin forestall decaying of wood past treating it with forest preservatives. But some of the wood preservatives may impairment humans and other creatures. For this reason if wood is used outdoor in situations where it is ofttimes wet or in close proximitly to liquid water, so wood must exist treated with wood preserving chemicals to achieve long term durability.
Wood preservatives are divided into two groups: Waterborne and oilborne chemicals.
About %75 of wood that is commercially treated today is treated with waterborne salts, and CCA is the compound used in treating for the greatest volume of wood.
Only creosote and pentachlorophenol are constructive protecting wood in directly ground contact. These are also the only two oilborne preservatives that provide general protection against disuse causing fungi, termites, marine tapping and other insects.
Oil based or oilborne preservatives are generally used for treating of wood used outdoors in industrial applications; such as ties, piling and poles.
In a serious situation, wood is treated with waterborne preservatives for example chromated copper arsenate and, later thorough seasoning, is retreated with creosote.
Remedial handling
Wood in service must be periodically retreated by brushing or a variety of other methods.
Retreatment of wood window frames, door frames and forest timber and beams is sometimes carried out past drilling holes in areas where disuse has begun and filling these holes with a suitable treating compound. Treating compound in the course of solid rods are more often than not preferred since it provides a boring release of active ingredients.
Retreatment of wood used in ground contact must be realized by application of pastes and wrapping with preservative impregnate bandages.
Abiotic Deterioration of wood:
Fire:
Another disadvantage of woods is that it easily catches fire. Wood consists of organic compounds which are composed mainly of carbon and hydrogen. They can combine with oxygen and burns. Because of these properties, woods is classified as a combustible material.
If the temperature of a inflammable gas is between 225°-260°C, it burns with a touch of flame. Later on the withdrawal of flame information technology will finish burning. If the temperature increases to 250°-270°C, it burns with a bear on of flame and goes on to burn down without a flame. If the temperature increases to 330°-520°C, wood begins to fire spontaneously. Chemical materials, specially extractives in woods structure crusade the burning point to change. For example, a resinous piece of pinewood can take hold of fire in lower temperatures. In addition to this, specific gravity and surface mass (m2/kg) touch the duration of flame. Wood burns harder when the specific gravity and surface mass and moisture content increment, and vice versa.
Using thick wood as a structure element is another style of extension of burning point. Outer surface burns and turns into charcoal. Charcoal, which forms on the surface of woods as it burns is a very effective heat insulator. Therefore big timbers burn very slowly. In add-on to this, woods is very practiced oestrus insulator besides. The outer surface of the wood is g°C and the interior part is all the same 40°C when a piece of thick woods is burning. For this reason, buildings with thick structure elements such as beams and columns do not collapse easily on fire. On the other manus, in steel constructions, as rut increases, steel faces deformation, and their resistance decreases and collapses, where wood is used preventive measures must be taken for condom against burn. In this example wood is not a dangerous textile.
Fire Retardants:
It is impossible to make wood noncombustible like inorganic materials. In club to prevent potential dangers, wood can be processed in some fire retardants.
Fire retardants may be divided into two categories: Coating and chemicals-water soluble salts-that are impregnated into the wood structure.
Coatings are used to reduce the formation of volatile, flammable gases by promoting rapid decomposition of the forest surface to charcoal and water. They also protect wood surface against loftier temperature water soluble salts e.thousand. diammonium phosphate, ammonium tetraborate, sodium acetate, alkali silicates, borax are used against fire hazards in wood. Wood tin can be impregnated past these chemicals. This type of process can contribute to the increment of the burning betoken and retard spread and penetration of flame.
Burn retardants only reduce the flammability of woods and irksome or eliminate progressive combustion. They do non prevent called-for totally in the presence of an external source of fire. In this case, wood does not go on burning once an external source of flames is removed.
Prof. Dr. Ramazan ÖZEN
President, Zonguldak Karaelmas University
Source: https://www.ktb.gov.tr/EN-98769/wood-as-a-building-material-it39s-benefits-and-disadvan-.html