13 MATERIALS AND FINISHES: BUILDING MATERIALS – TYPES, ADVANTAGES, DISADVANTAGES

K. Sudha Rani

INTRODUCTION

A building is a relatively permanent structure over a plot of land, usually enclosed by a roof, along with doors and windows in one or more levels, which forms an essential component in any life space planning. Traditionally, buildings were constructed from naturally available resources such as thatch, mud, sand, woods etc., but today, the advancement of technology has led to the evolution of more refined and complex building materials.

LEARNING OBJECTIVES

This chapter will enable the students to

F Know the different types of building materials available
F Understand the merits and demerits of each material
F Become aware of the application of each material.

TYPES OF BUILDING MATERIALS

Any material which contributes to the construction of a structure is called as a building material.
Building materials are classified based on

3.1.1 Origin:

Natural – thatch, mud, rock, etc

Man-made – cement, lime, bricks, stones, etc

3.2. Utility/Purpose:

Abrasive – diamond, silicon, garnet, etc

Adhesive – glues

Binding – Clay, lime, Cement, Bitumen, Mortar, Fly- ash, etc.

Covering – Asbestos, Cement sheets, roof tiles

Flooring – brick, ceramic, rubber, plastic, timber, glass, cement, concrete

Protective – paints , varnishes, etc.

Reinforcing – mild steel, tor steel

Solid material – Bricks, stone, iron, timber

Sound absorbent – Hair, felt, Plaster of Paris, Acoustic plaster,

Transparent – glass, plastic

3.3. Composition:

Rock -marble, granite, slate, and arids

Binder –lime, gypsum and Cement

Concrete – mixture of arids, agglomerates and water

Ceramic – bricks, tiles, porcelain, etc.

Others – Steel, Wood, Plastic, Glass

Major building materials

4.1. Stone

It is a non metallic naturally available material obtained from rocks. They are further classified as follows:

4.1.1 Geological – Based on the mode of formation, they are

Igneous rocks: formed by the cooling and solidifying of magma. Eg: Granite, quartz, basalt
Sedimentary rocks: The weathering action of natural agents like wind, frost, rain and flowing water disintegrate rocks and form deposits on the pre-existing rocks which get carried away from their place of origin. Eg: Gravel, sandstone, limestone.
Metamorphic Rocks: are rocks formed by the metamorphism of preformed rocks due to effect of high heat and pressure and chemicals Eg., Marble, Schitz and gneiss.

4.1.2 Physical – is based on their general structure,

Stratified rocks: have distinct layers and planes of formation. eg. Sedimentary
Unstratified: will not be in distinct layers and are typically granular eg Igneous
Foliated: are cleaved but only along one definite direction. eg Metamorphic

4.1.3 Che mical – Based on their chemical composition,

Siliceous are composed primarily of silica and are highly durable and strong.. Eg: quartzite and granites.
Argillaceous contain argil or clay as the major constituent. They are hard and durable. Eg: Slates and laterite.
Calcareoushave calcium carbonate as the chief component. Eg: Limestone and

Advantages of stone as a building material

Possess good compressive strength and are durable.
More economical
Do not cause any toxic emissions.
Reflects the ethnicity of a locality.

Disadvantages

Have poor tensile strength
May decay if not preserved properly.
Transportation and maintenance are expensive
Require skilled workforce.

Applications

For the construction of foundations, walls, columns, and arches of buildings.
Crushed stones as blocks in construction of dams, abutments, piers, bridge, etc.
As slabs and blocks are used for retaining walls, footpaths, roofing and paving around buildings.

2. Ceramics

Derives its name from the Greek word “keramos” which means potter’s earth.

Classification

4.2.1. Clay products: are obtained from the chemical weathering of igneous rocks. eg :Tiles, Terra-cotta, earthenware, stoneware, porcelain and bricks.

Tiles: are thin slabs of brick burnt in a kiln. Available in two categories: common tiles and encaustic tiles.

Common tiles are available in different varieties, such as drain tiles, floor/paving tiles and roof tiles, which are used for paving, flooring and roofing.
Encaustic tiles are primarily used for decorative purposes on floors, walls, roofs and ceilings. They contain colouring materials and finer clay particles to give a specific print or colour after manufacture.

Terracotta : refers to baked earth. It has a soft, porous texture made from local clay with glazes containing galena. It is used in the form of blocks, arches, columns, ornamental work, etc. It is strong and durable, easy to clean and available in different colours.
Earthenware: is manufactured by mixing required quantities of clay, sand and crushed pottery which are burnt at low temperatures followed by cooling. It is soft and porous but can be glazed to make them impervious.
Stoneware: are articles prepared from refractory clays mixed with stone and crushed They are denser, compact, strong, impervious, durable and resistant to corrosive fluids. Frequently used as wash basins, sewer pipes, water closets etc.
Porcelain: indicates fine earthenware that is white thin, semi transparent, hard, brittle and porous, obtained from a mixture of clay, feldspar, quartz a nd minerals. Generally used as sanitary ware, electric insulators, storage vessels etc.

4.2.2. Refractory products: are ceramics that can stand high temperatures. They are classified based on their chemical properties and resistance to temperature as

Acidic refractory materials which include fire clay, quartzite and silica. These find use as fire bricks, silica bricks and hollow tiles.
Basic refractory materials which are dolomite and magnesia that find use as refractory bricks and magnesia bricks.

4.2.3. Glass: is made from mixtures of sand and silicates, in a very hot fire stove called a kiln. It is amorphous, transparent and brittle. Certain additives are added to the mixture to produce glass with shades of various colours, characteristics or varieties.

Soda lime glass is a mixture of sodium silicate and calcium silicate.
Potash lime glass contains a mixture of potassium silicate and calcium silicate
Potash lead glass is a mixture of potassium silicate and lead silicate.
Common glass is produced from silicates of sodium, calcium and iron.
Borosilicate glass is made up of silica (70-80 percent), boric oxide (7-13 percent) and smaller amounts of aluminium oxide and alkalis like sodium and potassium oxides.

Advantages of ceramic

Offers good resistance to chemicals
Available in elegant colours
Usually not affected by air or water
Can be cleaned easily

Disadvantages

They are expensive
Cannot ensure building security
Unsafe for earthquake prone areas
Extra care required to handle ceramics

Applications

Tiles are generally used for paving, flooring and roofing and on interior walls.
Terracotta is mainly used for fireplaces and flooring and as a decorative material in place of stones for ornamental parts of building.
Earthenware is used for making drain pipes, cable conduits and partition blocks.
Glass is used as roofs, doors, windows and facades etc.

4.3. Bricks

They are one of the main clay products, which are rectangular blocks of uniform size made by moulding and subsequent drying and burning. Bricks were traditionally handmade, but at present, they are machine made.

Classification

Depending on the type of heat treatment given after the moulding of clay, bricks can be classified as

4.3.1. Sundried : are those dried in the sun after the moulding process. They are of inferior quality and can be used only for the construction of provisional a nd economical structures.

4.3.2. Burnt: are those subjected to high temperatures after the process of moulding. They are categorised as:

First class –the most superior quality with sharp, smooth and regular edges and
Second class – are considerably rough and irregular in shape, and are used in places where plastering is done.
Third class – have irregular rough surfaces with distorted and uneven edges
Fourth class- Over burnt bricks that have a very compact structure and are frequently used as aggregate for concrete.

To give interest and to suit various structures, bricks are available in different forms such as bull nose bricks, channel, coping, cow nose, curved sector hollow bricks, paving, perforated and purpose-made ones.

Advantages

Very economical since the raw materials used for brick is indigenous
Compared to stone work, brickwork construction and maintenance is less expensive
Does not require sophisticated mechanical devices at the work site.
Fire resistance qualities.
Prospects for reuse and recycling.

Disadvantages

Time consuming.
Possess very low tensile strength.
Absorbs water easily and can be a source of dampness in the building.
Cleaning brick surfaces is a tedious job.

Applications

For constructing walls and partitions and in foundations.
For building different structures such as lining sewer lines, furnaces and chimneys.
Pavers for footpaths and aggregates in concrete.
For developing architectural effects and aesthetic purposes

Alternatives to stone and bricks

Fly ash bricks- made of fly ash which is the waste by product of thermal plants
Sand lime bricks – prepared from sand, lime, water and pigment.
Concrete blocks -also called artificial stones made with cement, sand and solid

4.4. Cement

It refers to a fine powder which sets and hardens when mixed with water; it is obtained by burning a mixture of lime stone and clay at high temperatures, followed by grinding with small quantity of gypsum.

Types

4.4.1. Ordinary Portland Cement (OPC): the most extensively used type

4.4.2. Portland Pozzolana Cement (PPC): contains 10 – 30 percent of Pozzolana, a volcanic powder. Due to its lesser compressive strength, used mainly for plastering buildings and sewer lines.

4.4.3. High alumina: composed of lime and bauxite. It offers more resistance to sulphate and acid attack.

4.4.4. Acid resistant: contains acid resistant compounds like sodium silicate, quartz and quartzite.

4.4.5. Expanding: has the ability of expanding due to the presence of an expanding medium and a stabilising agent.

4.4.6. Hydrophobic: contains substances such as stearic acid, oleic acid, and oxidised petrolatum, that form a fine lining around the cement particles.

4.4.7. Quick setting: sets very quickly after adding water due to the presence of fine aluminium sulphate with reduced amounts of gypsum

4.4.8. White: lacks colouring oxides like iron, manganese, chromium and chlorine. This variety has become absolutely essential nowadays.

4.4.9. Rapid hardening: Has a higher percentage of lime in the cement composition and is burned at great temperatures which hastens the hardening.

4.4.10. Coloured: obtained when 5 to 10 percent of mineral pigments of the required colour are mixed to ordinary cement.

Advantages

Adds strength to masonry work.
Have relatively stable properties.
Offers good moisture resistance.

Disadvantages:

Not an eco friendly material
High transportation costs
Being cold, it is an unyielding material to live in
Long time storage is problematic

Applications

Construction of strong structures like dams, bridges etc
For making of cement concrete*
Joints for pipes, drains, etc.
For foundations, foot paths etc.
As mortar** for masonry work, plastering and pointing

*Cement concrete- a mixture of cement, sand, crushed rock, pebbles and water in suitable proportions. As it comprises of both coarse (broken bricks, broken stones, gravel) and fine (sand#, surki) aggregates##, along with cement (binder), when mixed with water, it produces a plastic mass that hardens on curing. Variations of cement concrete are water proofing, coloured, light weight, no- fines, pre-cast, ready mix and transit mix.

**Mortar- a paste obtained from mixing a binding material like lime or cement and a fine aggregate like sand with some amount of water.

#Sand – a natural resource that contains small grains of silica. Usually sand is categorised based on the size of the particles as fine sand (used in plastering), coarse sand (used in masonry work) and gravelly sand (used in concrete work). Recently, hard stones are crushed down to create sand artificially,

##Aggregate- inert or chemically inactive materials that develops a bonding with cement to form concrete; they are classified as coarse aggregate and fine aggregate. Mostly they are from natural sources such as crushed stones, gra vel or sand. Aggregates could also be obtained artificially from broken bricks, crushed blast furnace slag and from foamed slag, coke, or saw dust also.

4.5. Timber

Wood used for construction purposes is referred to as timber. It is one of the most widely used building materials across the world owing to its reasonable costs, ease of working, attractive appearance, and good life if maintained properly. Three forms of wood commonly found are,

Standing timbe r– the wood of a living tree that is good for construction.
Rough timbe r –obtained after felling a tree
Conve rted timber – Processed rough timber made into planks, battens, posts and beams.

Classification based on

4.5.1. Mode of growth: Trees which grow outwards in the form of concentric circles are classified as Exogenous trees. They are of two types, namely, the coniferous trees (deodar, pine, etc) and deciduous trees (oak, teak, etc) which yield soft and hard wood respectively. Trees which grow inwards to form longitudinal mass are called Endogenous trees, Eg: Bamboo and cane.

4.5.2. Durability: High durability trees with an average life of >10 years, Moderate durability trees with an average life of 5-10 years, and Low durability trees with an average life of 5 year

4.5.3. Modulus of elasticity (E): It is determined by conducting the bending test on the standard tree specimen.

4.5.4. Grading: are found as Special grade, Grade I and Grade II. The grading is done by studying certain criteria of the wood such as permissible stress, defects and so on

4.5.5. Availability: as most common, common and less common. The availability of the trees varies from 335-1415 m3 per year approximately

Advantages

C Have good heat, sound and electrical resistance
C Easily workable.
C Wooden houses are cool in summer and warm in winter
C Relatively cheap and economical
C High strength in proportion to weight

Disadvantages

D Not fire resistant
D Likely to crack, warp and decay if not maintained well
D Not suitable for cyclonic weather and regions subjected to natural calamities.

Applications

ü Door and window frames, shutters, roofing materials
ü Framework of cement concrete, scaffolding, centering of an arch etc
ü Temporary bridges

4.6. Metals

These are defined as opaque, fusible, ductile, and typically lustrous substances that are good conductors of electricity and heat. It is a chemical element that distinguishes it from an alloy.

Classification

Cast iron, steel and wrought iron which contain iron as their chief constituent are called ferrous metals. Metals that do not have iron as a main constituent are non ferrous metals.

4.6.1. Ferrous metals

Cast iron: manufactured by re- melting pig iron (crude form of iron ore) with coke and limestone. It comprises of carbon (2-4 percent)
Steel: forms an intermediate stage between cast iron and wrought iron, with 0.25 – 1.50 percent of carbon.
Wrought iron: purest form of iron containing less carbon (about 0.15 percent). It is unaffected by saline water.

4.6.2. Non ferrous metals have limited use only. eg aluminium, cobalt, copper

Ferrous metals- Advantages

High strength to weight ratio
Facilitates easy modification and repair
High durability
Recycling possibilities.

Disadvantages

Vulnerable to corrosion (except stainless steel)
Requires more energy and strength to form or to re-work into a required shape.
High cost of final finishing & polishing

Non ferrous metals- Advantages

More malleable facilitating greater potential to restructure
Good tensile strength
High conductivity of electric current
Resistance to corrosion

Disadvantages

Light-weight and have limited strength capabilities.
Are costlier than ferrous metals.

Applications

Ferrous metals

Cast iron- Cisterns, pipes, sanitary fittings, ornamental castings
Wrought iron – Rivets, chains, ornamental iron work, handrails, roofing sheets, etc.
Steel -Stone mason’s tools and wood working tools, sheet metal and tin plate.

Non Ferrous metals

Brass – water taps, ornaments
Tin –used for coating steel to form tinplate
Zinc –galvanised items

4.7. Miscellaneous building materials

Plastic is a natural or synthetic organic material made from resin with or without the use of fillers, plasticizers and solvents. Plastic sheets or tiles are used in flooring and pipes for water supply in buildings. Other uses are taps, bath tubs and cistern ball floats.
Asbestos is a flexible, non porous and naturally occurring fibrous mineral, composed of silicates of calcium and magnesium with small amounts of iron oxide and alumina, mainly used in roofing, and pipes.
Rubber either natural or synthetic after necessary processing are used to produce polymer concrete, flooring tiles, etc.
Gypsum is a hydrated sulphate of calcium with other elements like silica, carbonate of lime, magnesia and iron oxide. The plaster of Paris, is a product of gypsum powder.
Accessory ite ms for joining

Adhesive is used to join two or more surfaces into a single unit.
Solder is an alloy used to join metal pieces
Sealants are materials that can seal cracks or joint.
Joint fillers helps to fill the sides of joints subjected to relative movements.

Wate r proofing materials

Asphalt which consists of inert mineral matters such as lime and silica
Bituminous materials composed of bitumen and vegetable or animal fibres.
Epoxy materials are useful for making damp proof courses, on pavements, terraces and tanks.

Electric insulators

Non metallic materials highly resistant to the conduction of electricity like glass, plastics, mica, asbestos, porcelain, bakelite, rubber and wax, are used as electrical fittings.

Thermal insulators

Aerated concrete, hollow bricks, gypsum boards, fibre boards and asbestos cement boards are used in buildings to minimise heat losses in the structures through the walls.

Sound insulators

Porous materials like cellular concrete, asbestos, glass and mineral wool find application in ceilings and floorings to control noise.

Building mate rials utilised for the various components of a building

CONCLUSION:

The main idea of constructing a building is to last a lifetime. Thus knowing in detail about the merits and demerits of all building materials helps one to judge the apt material suitable for the environment. Without the choice of the right building material, the infrastructure could well falter. Therefore, the role of these materials in the construction of a healthy infrastructure is huge, in providing a safe and secured habitat.

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BIBLIOGRAPHY/ REFERENCES

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