Hanan Nur r i0111048 - Wood Structures

WOOD-BASED PRODUCTS Wood Structures 2014

HANAN NUR RAHMAHI0111048

WOOD-BASED PRODUCTS I0111048

I. IntroductionThere are many consideration to choose a building material.

It depends on technical character, economic trait and the building aesthetics.

If we want to choose wood as the building material, of course we have to understand the character of the wood itself. Wood has many positive characteristics, including low embodied energy, low carbon impact, and sustainability. In the UnitedStates, a little more than half the wood harvested in the forest ends up as building material used in construction.

Until today, wood is still becoming the most used and needed building material. Wood's general characteristics are:

1. Wood is a renewable resources2. Wood is easy to process3. Wood has specific quality that can't be imitated by

others materials.

Throughout history, the unique characteristics and abundance of wood have made it a natural material for homes and other structures, furniture, tools, vehicles, and decorative objects. Today, for the same reasons, wood is prized for a multitude of uses.

II. Wood-Based ProductsA. Type of woods

The more one knows about the unique characteristics of wood and its source, the better one can understand the degree of warmth and beauty that it brings to our everyday needs.

The classification of wood has historically always been either hard wood; any leaf bearing tree, and soft wood; any cone bearing tree. These terms can be confusing since some leaf bearing trees can have very soft wood and some coniferous can have very hard woods.

1. SoftwoodsSoftwoods are available directly from sawmills, wholesale

and retail yards, or lumber brokers. Softwood lumber and plywood are used in construction for forms, scaffolding, framing, sheathing, flooring, moulding, paneling, cabinets, and many other building components. Softwoods may also appear in the form of shingles, sashes, doors, and other millwork, in addition to some rough products such as timber and round posts.

1.1. Example of Softwoods1.1.1. PinePine is a softwood which grows in most

areas of the Northern Hemisphere. There are more than 100 species worldwide.

Pine is a soft, white or pale yellow wood which is light weight, straight grained and lacks figure. It resists shrinking and swelling. Knotty pine is oeffect. Pine is often used for country or provincial furniture. Pickled, whitened, painted and oil finishes are often used on this wood.

1.1.2. AshThere are 16 species of ash which grow in

the eastern United States. Of these, theash is the largest and most commercially

WOOD-BASED PRODUCTS

The classification of wood has historically always been either hard wood; any leaf bearing tree, and soft wood; any cone bearing tree. These terms can be confusing since some leaf bearing trees can have very soft wood and some coniferous

y hard woods.

SoftwoodsSoftwoods are available directly from sawmills, wholesale

and retail yards, or lumber brokers. Softwood lumber and plywood are used in construction for forms, scaffolding, framing, sheathing, flooring, moulding, paneling, cabinets, poles and piles, and many other building components. Softwoods may also appear in the form of shingles, sashes, doors, and other millwork, in addition to some rough products such as timber and round posts.

1.1. Example of Softwoods

oftwood which grows in most areas of the Northern Hemisphere. There are more than 100 species worldwide.

Pine is a soft, white or pale yellow wood which is light weight, straight grained and lacks figure. It resists shrinking and swelling. Knotty pine is often used for decorative

Pine is often used for country or provincial furniture. Pickled, whitened, painted and oil finishes are often used on this

There are 16 species of ash which grow in the eastern United States. Of these, the white ash is the largest and most commercially

I0111048

The classification of wood has historically always been either hard wood; any leaf bearing tree, and soft wood; any cone bearing tree. These terms can be confusing since some leaf bearing trees can have very soft wood and some coniferous trees

Softwoods are available directly from sawmills, wholesale and retail yards, or lumber brokers. Softwood lumber and plywood are used in construction for forms, scaffolding, framing,

poles and piles, and many other building components. Softwoods may also appear in the form of shingles, sashes, doors, and other millwork, in addition to some rough products such as timber and round posts.

which is light weight, straight grained and lacks figure. It resists ften used for decorative

Pine is often used for country or provincial furniture. Pickled, whitened, painted and oil finishes are often used on this

important.

Ash is a hard, heavy, ring porous hardwood. It has a prominent grain that resembles oak, and a white to light brown color. Ash can be differentiated from hickory (pecan) which it also resembles, by white dots in the darker summerwood which can be seen with the naked eye. Ash burls have a twisted, interwoven figure. Ash is widely used for structural frames and steam bent furniture pieces. It is often less expensive than comparable hardwoods.

2. HardwooHardwoods are used in construction for flooring,

architectural woodwork, interior woodwork, and paneling. These items are usually available from lumberyards and building supply dealers. Most hardwood lumber and dimension stock are remanufactured into dunnage, and blocking.

Hardwood lumber and dimension stock are available directly from manufacturers, through wholesalers and brokers, and from some retail yards. Both softwood and hardwood products are distributed throughout the United States. Local preferences and the availability of certain species may influence choice, but a wide selection of woods is generally available for building construction, industrial uses, remanufacturing, and home use.

2.1. Example of Hardwoods2.1.1. OakOak is the most widely used hardwood.

There are more than

WOOD-BASED PRODUCTS

Ash is a hard, heavy, ring porous hardwood. It has a prominent grain that resembles oak, and a white to light brown color. Ash can be differentiated from hickory (pecan) which it also

white dots in the darker summerwood which can be seen with the naked eye. Ash burls have a twisted, interwoven

Ash is widely used for structural frames and steam bent furniture pieces. It is often less expensive than comparable

HardwoodsHardwoods are used in construction for flooring,

architectural woodwork, interior woodwork, and paneling. These items are usually available from lumberyards and building supply dealers. Most hardwood lumber and dimension stock are remanufactured into furniture, flooring, pallets, containers, dunnage, and blocking.

Hardwood lumber and dimension stock are available directly from manufacturers, through wholesalers and brokers, and from some retail yards. Both softwood and hardwood products are

ted throughout the United States. Local preferences and the availability of certain species may influence choice, but a wide selection of woods is generally available for building construction, industrial uses, remanufacturing, and home use.

le of Hardwoods

Oak is the most widely used hardwood. There are more than 60 species of oak grown in

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Ash is a hard, heavy, ring porous hardwood. It has a prominent grain that resembles oak, and a white to light brown color. Ash can be differentiated from hickory (pecan) which it also

white dots in the darker summerwood which can be seen with the naked eye. Ash burls have a twisted, interwoven

Ash is widely used for structural frames and steam bent furniture pieces. It is often less expensive than comparable

Hardwoods are used in construction for flooring, architectural woodwork, interior woodwork, and paneling. These items are usually available from lumberyards and building supply dealers. Most hardwood lumber and dimension stock are

furniture, flooring, pallets, containers,

Hardwood lumber and dimension stock are available directly from manufacturers, through wholesalers and brokers, and from some retail yards. Both softwood and hardwood products are

ted throughout the United States. Local preferences and the availability of certain species may influence choice, but a wide selection of woods is generally available for building construction,

the U.S., which can be separated into two basic varieties; white and red. The red variety is also known as black oak (a reference to its bark).

Oak is a heavy, strong, light colored hardwood. It is ring porous, due to the fact that more and larger conductive vessels are laid down early in the summer, rather than later. Prominent rings and large pores give oak a course texture and promigrain. Oak also has conspicuous medullary rays which can be seen as "flakes" in quarter sawed oak lumber.

Oak is the most popular wood used to craft American and English country designs. It is also used for Gothic and William & Mary reproductions,contemporary pieces.

2.1.2. TeakTeak (Tectona grandis

commercial quantities in India, Burma,Laos, Cambodia, Vietnam, and the East Indies.

Teakwood has a coarse,usually straight grained,heartwood has excellentdegree of natural durability.

Teak is generally worked with moderate ease with handmachine tools. However, the presence of sFinishing and gluing are satisfactory, althoughbe necessary to ensure good bonding of

Teak is one of the most valuable woods, but its use is limitedby scarcity and high cost. Because teak corrosion when in contact with metal, it is extremely

WOOD-BASED PRODUCTS

the U.S., which can be separated into two basic varieties; white and red. The red variety is also known as black oak (a reference to

Oak is a heavy, strong, light colored hardwood. It is ring porous, due to the fact that more and larger conductive vessels are laid down early in the summer, rather than later. Prominent rings and large pores give oak a course texture and promigrain. Oak also has conspicuous medullary rays which can be seen as "flakes" in quarter sawed oak lumber.

Oak is the most popular wood used to craft American and English country designs. It is also used for Gothic and William & Mary reproductions, as well as many transitional and contemporary pieces.

Tectona grandis) occurs in quantities in India, Burma, Thailand,

Vietnam, and the East Indies.

Teakwood has a coarse, uneven texture (ring porous), isusually straight grained, and has a distinctly oily feel. The heartwood has excellent dimensional stability and a very high degree of natural durability.

Teak is generally worked with moderate ease with handmachine tools. However, the presence of silica oftenFinishing and gluing are satisfactory, although pretreatment may be necessary to ensure good bonding of finishes and glues.

Teak is one of the most valuable woods, but its use is limitedby scarcity and high cost. Because teak does not causecorrosion when in contact with metal, it is extremely

I0111048

the U.S., which can be separated into two basic varieties; white and red. The red variety is also known as black oak (a reference to

Oak is a heavy, strong, light colored hardwood. It is ring porous, due to the fact that more and larger conductive vessels are laid down early in the summer, rather than later. Prominent rings and large pores give oak a course texture and prominent grain. Oak also has conspicuous medullary rays which can be seen

Oak is the most popular wood used to craft American and English country designs. It is also used for Gothic and William &

as well as many transitional and

uneven texture (ring porous), isand has a distinctly oily feel. The

dimensional stability and a very high

Teak is generally worked with moderate ease with hand and ilica often dulls tools.

pretreatment may finishes and glues.

Teak is one of the most valuable woods, but its use is limiteddoes not cause rust or

useful in the

shipbuilding industry, for tanks and vats, andrequire high acid resistance. Teak is currentlyconstruction of boats, furniture, flooridecorative veneer.

2.1.3. MerbauMerbau (Malaysia) is name

species of the genus bijuga. Intsia is distributed throughoutMalaysian region, Indonesia,many western Pacific islands, as well

Freshly cut yellowish to orangebrown or dark red–coarse, and the grain is straight to interlocked orstrength of air-dried merbau(Carya), but density is somewhat lower12% moisture content). Thebut stains black in the

Merbau is rather difficult toteeth and dulls cutting edges.smoothly in most operationsdurability and high resistanceresists treatment,preservatives. Merbaucabinets, flooring, musical instruments, and specialty items.

B. Wood Based MaterialsThe term “wood

shaped products made from various intermfrom wood. The best known products of this type in Europe are

WOOD-BASED PRODUCTS

shipbuilding industry, for tanks and vats, and for fixtures that require high acid resistance. Teak is currently used in the construction of boats, furniture, flooring, decorative objects, and decorative veneer.

2.1.3. MerbauMerbau (Malaysia) is name applied to

genus Intsia, most commonly I. distributed throughout the Indo–

region, Indonesia, Philippines, and Pacific islands, as well as Australia.

Freshly cut yellowish to orange–brown heartwood turns–brown on exposure to air. The texture

coarse, and the grain is straight to interlocked ordried merbau is comparable with that of hickory

), but density is somewhat lower (800 kg m–3 (50 lb ft12% moisture content). The wood dries well with little degrade but stains black in the presence of iron and moisture.

Merbau is rather difficult to saw because it sticks to saw teeth and dulls cutting edges. However, the wood dresses smoothly in most operations and finishes well. Merbau has good durability and high resistance to termite attack. The heartwood resists treatment, but the sapwood can be treapreservatives. Merbau is used in furniture, fine joinery, turnery,

musical instruments, and specialty items.

Wood Based MaterialsThe term “wood-based materials” usually stands for panel

shaped products made from various intermediate products gained from wood. The best known products of this type in Europe are

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for fixtures that used in the

decorative objects, and

brown heartwood turnsbrown on exposure to air. The texture is rather

coarse, and the grain is straight to interlocked or wavy. The that of hickory 3 (50 lb ft–3) at

wood dries well with little degrade

because it sticks to saw However, the wood dresses

and finishes well. Merbau has good to termite attack. The heartwood

but the sapwood can be treated with is used in furniture, fine joinery, turnery,

musical instruments, and specialty items.

based materials” usually stands for panel-ediate products gained

from wood. The best known products of this type in Europe are


most easily categorised under the terms “plywood”, “flake board” and “fibre board”.

In their applications, a general differentiation is made between those used in the construction industry (mostly static load carrying) and those used in furniture and packaging (non-load or low-load carrying). Countless new developments – mainly from America and Scandinavia – now mean the above categorisation is no longer accurate. Besides the traditional panel-shaped materials, pole or beam-shaped materials or composite products, like I-girders, have now been developed to make up for the decreasing availability of high quality solid wood or veneer wood.

Table II–1. Classification of woodbased compositesa

Veneer-based materialPlywoodLaminated veneer lumber (LVL)Parallel-strand lumber (PSL)LaminatesGlue-laminated timbersOverlayed materialsLaminated wood–nonwood compositesb

Multiwood composites (COM-PLYc)Composite materialFiberboard (low-, medium-, or high-density)Cellulosic fiberboardHardboardParticleboardWaferboardFlakeboardOriented strandboard (OSB)


Laminated strand lumber (LSL)Oriented strand lumber (OSL)Wood–nonwood compositesWood fiber–polymer compositesInorganic-bonded compositesaAdapted from Maloney (1986).bPanels or shaped materials combined with nonwoodmaterials such as metal, plastic, and fiberglass.cRegistered trademark of APA–The Engineered Wood Association.

Table II–2. Commercial product or performance standards for wood-based composites


Figure II–1. Basic wood elements, from largest to smallest (Kretschmann and others 2007).

Figure II–2. Examples of various composite products.


1. Conventional Wood-Based Composite PanelsConventional wood-based composites are manufactured

products made primarily from wood with only a few percent resin and other additives.

1.1. PlywoodPlywood is a panel product built up wholly or primarily of

sheets of veneer called plies. It is constructed with an odd number of layers with the grain direction of adjacent layers oriented perpendicular to one another. A layer can consist of a single ply or of two or more plies laminated with their grain direction parallel. A panel can contain an odd or even number of plies but always an odd number of layers.

The outside plies are called faces, or face and back plies. Inner plies are plies other than the face or back plies. The outerlayers and all odd-numbered layers have their grain directionoriented parallel to the long dimension of the panel. The grain in even-numbered layers is perpendicular to the length of the panel. Inner plies whose grain direction runs parallel to that of the faces are termed “centers” whereas inner plies whose grain direction runs perpendicular to that of the faces are termed “crossbands.”

To distinguish the number of plies (individual sheets of veneer in a panel) from the number of layers (number of times the grain orientation changes), panels are sometimes described as three-ply, three-layer or four-ply, three-layer, etc. The center layer may be veneer, lumber, particleboard, or fiberboard; however, all-veneer construction is most common in construction and industrial plywood. Plywood panels are used in various


applications, including construction sheathing, furniture, and cabinet panels.

Plywood is also used as a component in other engineeredwood products and systems in applications such as prefabricatedI-joists, box beams, stressed-skin panels, and panelized roofs.

1.2. Oriented StrandboardOriented strandboard (OSB) is an engineered structural-use

panel manufactured from thin wood strands bonded togetherwith water-resistant resin, typically PF or pMDI. It is usedextensively for roof, wall, and floor sheathing in residential and commercial construction.

The wood strands typically have an aspect ratio (strand length divided by width) of at least 3. OSB panels are usually made up of three layers of strands, the outer faces having longer strands aligned in the long-direction of the panel and a core layer that is counteraligned or laid randomly using the smaller strands or fines.

The orientation of different layers of aligned strands givesOSB its unique characteristics, including greater bending strength and stiffness in the oriented or aligned direction. Control of strand size, orientation, and layered construction allows OSB to be engineered to suit different uses.

OSB technology and the raw material used originally evolved from waferboard technology, for which aspen was the predominant wood species used. As the industry learned to control strand size, placement, and orientation, the performanceand utility of OSB products improved to the point that their performance was similar to that of structural plywood.


As a result, product acceptance and the industry expanded as OSB began to replace softwood plywood in construction applications.

Figure II–3. Schematic of OSB manufacturing process. (Courtesy of TECO, Sun Prairie, Wisconsin.)

1.3. ParticleboardParticleboard is produced by mechanically reducing the

wood raw material into small particles, applying adhesive to the particles, and consolidating a loose mat of the particles with heat and pressure into a panel product.

The particleboard industry initially used cut flakes as a raw material. However, economic concerns prompted development ofthe ability to use sawdust, planer shavings, and to a lesser extent, mill residues and other waste materials.


To manufacture particleboard with good strength, smooth surfaces, and equal swelling, manufacturers ideally use a homogeneous raw material. Particleboard is typically made in layers. But unlike OSB, the faces of particleboard usually consist of fine wood particles and the core is made of coarser material. The result is a smoother surface for laminating, overlaying, painting, or veneering.

Particleboard is readily made from virtually any wood material and from a variety of agricultural residues. Low-density insulating or sound-absorbing particleboard can be made from kenaf core or jute stick. Low-, medium-, and high-density panels can be produced with cereal straw, which has been used in North America. Rice husks are commercially manufactured into medium-and high-density products in the Middle East. All other things being equal, reducing lignocellulosic materials to particles requires less energy than reducing the same material into fibers.

However, particleboard is generally not as strong as fiberboard because the fibrous nature of lignocellulosics (that is, their high aspect ratio) is not exploited as well.

Particleboard is widely used in furniture, where it is typically overlaid with other materials for decorative purposes. It is the predominant material used in ready-toassemble furniture. Particleboard can also be used in flooring systems, in manufactured houses, and as underlayment.

Thin panels can also be used as a paneling substrate. Sincemost applications are interior, particleboard is usually bonded with a UF resin, although PF and MF resins are sometimes used for applications requiring more moisture resistance.


1.4. FiberboardThe term fiberboard includes hardboard, medium-density

fiberboard (MDF), and cellulosic fiberboard. Several things differentiate fiberboard from particleboard, most notably the physical configuration of the wood element. Because wood is fibrous by nature, fiberboard exploits the inherent strength of wood to a greater extent than does particleboard. To make fibers for composites, bonds between the wood fibers must be broken. Attrition milling, or refining, is the easiest way to accomplish this.

During refining, material is fed between two disks with radial grooves. As the material is forced through the preset gap between the disks, it is sheared, cut, and abraded into fibers and fiber bundles. Refiners are available with single- or double-rotating disks, as well as steam-pressurized and unpressurized configurations. Refining can be augmented by steaming or chemical treatments.

Steaming the lignocellulosic weakens the lignin bonds between the cellulosic fibers. As a result, fibers are more readily separated and are usually less damaged than fibers processed by dry processing methods. Chemical treatments,usually alkali, are also used to weaken the lignin bonds.

Although treatments help increase fiber quality and reduce energy requirements, they may also reduce yield and modify the fiber chemistry. For MDF, steam-pressurized refining is typical.Fiberboard is normally classified by density and can be made by either dry or wet processes.

Dry processes are applicable to boards with high density(hardboard) and medium density (MDF). Wet processes are


applicable to both high-density hardboard and low-densitycellulosic fiberboard. The following subsections briefly describethe manufacturing of high- and medium-density dryprocessfiberboard, wet-process hardboard, and wet-process low-density cellulosic fiberboard.

2. Structural Composite LumberStructural composite lumber (SCL) was developed in

response to the increasing demand for high-quality lumber at a time when it was becoming difficult to obtain this type of lumber from the forest resource.

Structural composite lumber products are characterized by smaller pieces of wood glued together into sizes common for solid-sawn lumber. One type of SCL product is manufactured by laminating veneer with all plies parallel to the length. This product is called laminated veneer lumber (LVL) and consists of speciallygraded veneer.

Another type of SCL product consists of strands of wood orstrips of veneer glued together under high pressures and temperatures. Depending upon the component material, this product is called laminated strand lumber (LSL), parallel strand lumber (PSL), or oriented strand lumber (OSL).

These types of SCL products can be manufactured from raw materials, such as aspen or other underutilized species, that are not commonly used for structural applications. Different widths of lumber can be ripped from SCL for various uses.

Compared with similar size solidsawn lumber, SCL often provides a stronger, more reliable structural member that can often span greater distances and has less dimensional change.


Structural composite lumber is a growing segment of the engineered wood products industry. It is used as a replacementfor lumber in various applications and in the manufacture of other engineered wood products, such as prefabricated wood I-joists, which take advantage of engineering design values that can be greater than those commonly assigned to sawn lumber.

2.1. Laminated Veneer LumberToday LVL is commonly used as the flanges in composite I-

joists. Veneer for the manufacture of LVL must be carefully selected for the product to achieve the desired engineering properties.

Veneers are often sorted using ultrasonic testing to ensure that the finished product will have the desired engineering properties. End joints between individual veneers may be staggered along the product to minimize their effect on strength. These end joints may be butt joints, or the veneer ends may overlap for some distance to provide load transfer. Some producers provide structural end joints in the veneers using either scarf or fingerjoints.

LVL may also be made in 2.4-m (8-ft) lengths, having no end joints in the veneer; longer pieces are then formed by end-jointing these pieces to create the desired length. Sheets of LVL are commonly produced in 0.6- to 1.2-m (2- to 4-ft) widths in a thickness of 38 mm (1.5 in.).

Continuous presses can be used to form a potentially endless sheet, which is cut to the desired length. Various widths of lumber can be manufactured at the plant or the retail facility.


2.2. Parallel Strand LumberParallel strand lumber (PSL) is defined as a composite of

wood strand elements with wood fibers oriented primarily along the length of the member.

The least dimension of the strands must not exceed 6.4 mm (0.25 in.), and the average length of the strands must be a minimum of 150 times the least dimension. PSL is a proprietary product, sold as Parallam ®.

It is often used for large beams and columns, typically as a replacement of solid-sawn lumber or glulam. Parallel strand lumber is manufactured using veneer about 3 mm (1/8 in.) thick, which is then clipped into strands about 19 mm (3/4 in.) wide. These strands are commonly at least 0.6 m (24 in.) long.

The manufacturing process was designed to use the material from roundup of the log in the veneer cutting operation as well as other less than full-width veneer.

Thus, the process can utilize waste material from a plywood or LVL operation. Species commonly used for PSL include Douglas-fir, southern pines, western hemlock, and yellow-poplar, but there are no restrictions on using other species.

The strands are coated with a waterproof structural adhesive, commonly phenol-resorcinol formaldehyde, andoriented in a press using special equipment to ensure properorientation and distribution. The pressing operation results in densification of the material, and the adhesive is cured using microwave technology.

Billets larger than those of LVL are commonly produced; a typical size is 0.28 by 0.48 m (11 by 19 in.). This product can then


be sawn into smaller pieces, if desired. As with LVL, a continuous Press is used so that the length of the product is limited by handling restrictions.

2.3. Laminated Strand Lumber and Oriented Strand LumberLaminated strand lumber (LSL) and oriented strand lumber

(OSL) products are an extension of the technology used to produce oriented strandboard (OSB) structural panels.

The products have more similarities than differences. The main difference is that the aspect ratio of strands used in LSL is higher than for OSL (AF&PA 2006).

One type of LSL uses strands that are about 0.3 m (12 in.) long, which is somewhat longer than the strands commonly used for OSB.

Waterproof adhesives are used in the manufacture of LSL.One type of product uses an isocyanate type of adhesive that is sprayed on the strands and cured by steam injection.

This product needs a greater degree of alignment of the strands than does OSB and higher pressures, which result in increased densification.

Both LSL and OSL are proprietary products; LSL is sold as TimberStrand®. Applications such as studs and millwork are common.


Figure II–4. Generalized process for manufacturing PSL. (Courtesy of Level by Weyerhaeuser, Federal Way, Washington.)

III. ConclusionWood is something that really important as a material.

Wood still be a major choice of building material. With the right process, human can make wood to help them to build their life. There are many wood-based product that human created.

Even when wood is a renewable source, wood should be use carefully and wisely. To maintain the availability of wood, human should take care the woods and keep growing the tree. Also, human should know the characteristics of the wood first before they decide to use it so the wood will be useful in the right way.


References

Forest Product Laboratory. (2010), Wood Handbook, Wood as Engineering Material, Centennial Edition, USDA, Madison, Wisconsin.Frick, Ir. Heinz. (2003), Ilmu Konstruksi Bangunan Kayu, Kanisius, Yogyakarta, Indonesia.http://www.hoovedesigns.com/woods.htmlhttp://kontruksibangunan-kb1.blogspot.com/2013/03/jenis-dan-ciri-kayu-untuk-bahan-konstruksi.htmlhttp://www.wolman.de/en/infocenter_wood/the_raw_material_wood/wood_based_materials/index.php

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Hanan Nur r i0111048 - Wood Structures