Ritik KhandelwalINTERIOR DESIGN2nd SEMESTER

9782134439/9024262644

CONSTRUCTION MATERIALS

WOOD

What is construction material?•Construction material is any material which is used for construction purposes.•Many naturally occurring substances have been used to construct buildings :oClayoRocksoSandoWoodoTwigs oLeaves

Clay

Stone

Sand Twig

What is wood ?•Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants• It has been used for thousands of years for both fuel and as a construction

material.• It is an organic material, a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which resists compression. 

Classification of wood

WOOD

NATURAL WOOD

ENGINEERED WOOD

NATURAL WOOD

Where do we generally find wood ?

fuel

flooring

furniture

fuel

utensils musicalinstruments

sports equipments

Wood processing

Physical Properties 

Wood rings Water content Colour

Grains Knots

Classification of natural wood

NATURAL WOOD

HARD WOOD SOFT WOOD

Hard wood•Hardwood is wood from dicot angiosperm trees•The term may also be used for the trees from which the wood is derived; these are usually broad-leaved.•In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen• Hardwoods are not necessarily harder than softwoods

Hard woodCharacteristics •Hardwoods have a more complex structure than softwoods•Dark in colour •Expensive •Slower growth rate•Higher density•Heavy in weight•More fire resistant than soft wood•Strong in compression and tension

Hard woodExamples - Oak •Light in colour•Heavy •Ring porous•Open grain•Hard to work with.•When treated it looks classy and elegant

Hard woodExamples - Oak products

Hard woodExamples - Maple• Maple is so hard and resistant to shocks that it is often used for bowling alley floors.• Its diffuse evenly sized pores give the wood a fine texture and even grain.•Maple that has a curly grain is often used for violin backs.•Burls, leaf figure, and birds-eye figures found in maple are used extensively for veneers.

Hard woodExamples - Maple products

Hard woodExamples - Mahogany•  An easy to work wood•reddish brown in colour•Expensive•Strong• poorly defined annual rings•may display stripe, ribbon, broken stripe, rope, ripple, mottle, fiddle back or blister figures•excellent carving wood and finishes well

Hard woodExamples - Mahogany products

Hard woodExamples - Cherry•  hard•Strong•Light to red-brown wood•Resists warping and checking•Easy to carve and polish

Hard woodExamples – Cherry products

Hard woodExamples – Rubber wood• light colour•Medium density•Usually from the tree of rubber plantation•Advertised as eco-friendly woodoBecause It is not grown specially for timber but instead have timber as by product

Hard woodExamples – Rubber wood products

Soft wood•Softwood is wood from gymnosperm trees such as conifers• Softwood is the source of about 80% of the world's production of timber• Softwoods are not necessarily softer than hardwoods•The woods of long leaf pine, douglas fir, and yew are much harder in the mechanical sense than several hardwoods

Soft woodCharacteristics •Cheap comparative to hard wood•Faster rate of growth•Lower density•Softer than hardwood•Light in colour•Light in weight•Poor fire resistant•Strength in tension but week in sheer

Soft woodExamples - Ash •Hardwoods have a more complex structure than softwoods•Dark in colour •Expensive •Slower growth rate•Higher density•Heavy in weight•More fire resistant than soft wood•Strong in compression and tension

Soft woodExamples – Ash wood products

Soft woodExamples - Pine•  soft •White or pale yellow in colour•Light weight•Straight grains•Lack figures•Resists shrinking and swelling•knotty

Soft woodExamples – pine wood products

Soft woodExamples -Cedar• Knotty soft wood•Red brown colour with light steaks•Aromatic and moth repellant•Popular wood for lining drawers, chests and boxes• Brittle wood

Soft woodExamples – cedar wood products

Soft woodExamples –Red wood• The best quality redwood comes from the heartwood which is resistant to deterioration due to sunlight, moisture and insects•Redwood burls have a "cluster of eyes" figure. •They are rare and valuable.

Soft woodExamples – redwood products

NATURAL WOODseasoning

•Reduces moisture content of wood•There are two main reasons :i. Woodworking: when wood is used as a construction material,

whether as a structural support in a building or in wood working objects, it will absorb or desorb moisture until it is in equilibrium with its surroundings. Equilibration (usually drying) causes unequal shrinkage in the wood, and can cause damage to the wood if equilibration occurs too rapidly. The equilibration must be controlled to prevent damage to the wood.

ii. Wood burning: when wood is burned, it is usually best to dry it first.

Over exploitation of natural wood on nature•Deforestation•Desertification•Extinction of species•Forced migration•Soil erosion•Ozone depletion•Greenhouse gas increase•Natural hazard and desert

So Need for engineered wood

arises

ENGINEERED WOOD

• Also called composite wood, man-made wood, or manufactured board•Includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibers, or veneers or boards of wood, together with adhesives, or other methods of fixation to form composite materials• Engineered wood products are used in a variety of applications, from home construction to commercial buildings to industrial products.

Engineered woodPlywood• Plywood is a sheet material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another•This alternation of the grain is called cross-graining and has several important benefits: o it reduces the tendency of wood to split when nailed at the edgeso It reduces expansion and shrinkage, providing improved dimensional stabilityoIt makes the strength of the panel consistent across all directions.

Engineered woodBlock board• Blockboard is a wood based panel, made up of a core of softwood strips glued together• The strips may be up to about 28mm wide and are placed edge to edge and sandwiched between veneers of softwood, hardwood or thin MDF or particleboard, glued under high pressure•The internal strips are generally made of light weight poplar wood or spruce•To achieve maximum strength, it is important to ensure that the core runs lengthways•has very good screw holding•it has a good resistance to warping.

Engineered woodVeneers •  veneer refers to thin slices of wood, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels •Veneer is obtained either by "peeling" the trunk of a tree or by slicing large rectangular blocks of wood known as flitches• The appearance of the grain and figure in wood comes from slicing through the growth rings of a tree and depends upon the angle at which the wood is sliced

Engineered woodLaminates •  Lamination is the technique of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance or other properties from the use of differing materials•A laminate is usually permanently assembled by heat, pressure, welding, or adhesives

•   also known as chipboard•manufactured from wood chips, sawmill shavings, or even sawdust, and a synthetic resin or other suitable binder, which is pressed and extruded•It is a composite material

Engineered woodParticle board

•   made by breaking down hardwood or softwood residuals into wood fibres, often in a delibrator, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure• MDF is generally denser than plywood•It is made up of separated fibres• stronger and much denser than particle board

Engineered woodMedium Density Fiber board

•  also called hardboard• made out of exploded wood fibres that have been highly compressed• It differs from particle board in that the bonding of the wood fibres requires no additional materials,

although resin is often added•Unlike particle board, it will not split or crack

Engineered woodHigh Density Fiber board

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