The materials which are used for construction purpose or to construct different types of structure like a building, bridge, culvert, road, etc are known as construction and building materials. The materials used as construction materials are cement, sand, aggregate, stone, steel, and other types of metal.
Different types of materials are used also for decorative purpose as well as to make the structure attractive in appearance. These types of materials are tiles, marble, carped, pains, glass, etc.
So, let us describe one by one in detail of construction and building materials used.
1. Stones – as construction and building materials
Stones have used for building purpose from time immemorial. Building stones are obtained from rocks occuring in nature.
Different types of Rocks
Geologically the rocks are divided into three main types :-
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
a) Igneous Rocks:- These rocks are of volcanic origin which resultant of solidification of molten materials. Solidification may have occurred either in the interior of earth’s crust or upon its surface. They represent a crystalline glassy or fused texture. these rocks are hard, tough, dense, impervious, strong, and durable. Principle stones obtained from these are granite, basalt, trap, and dolerite.
b) Sedimentary Rocks:- The rocks which are formed from sediments through the agency of water, wind or glacier are called sedimentary rocks. Sedimentary rocks consist of grains of minerals which are cemented together by a binding material which may be calcarious, ferruginous, siliceous or argillaceous (clay).
They usually show the bedded structure arranged in layers. Principal stones obtained from these rocks are sandstone, shale, limestones, and laterite. Gravel, sand, silt, and clay considered as uncemented and unconsolidated sedimentary rocks.
c) Metamorphic rocks:- These are the rocks originally formed in either of the above two processes but, subsequently, changed or metamorphosed in colour, structure and texture due to intense heat and pressure below earth’s crust. The rocks have a foliated structure in general and also show layers of stratification which are not always uniform. Principal stones obtained from these Tocks are, quartzite, schist, slate, marble and gneisses.
Characteristics of a Good Building Stone
- The principal requirements of good building stone are hardness, toughness, uniformity in texture and colour and compact grained composition.
- Stones presenting uniform colour and texture are generally durable.
- Red and brown shades and mottled colour indicate the presence of injurious materials.
- the heaviest and compact grained stones are the strongest and most durable. A crystalline stone is superior to a non-crystalline one. Igneous and metamorphic rocks are generally heavier and more durable stronger and more durable than sedimentary rocks.
- A good stone should be free from, flaws, decay, veins, cracks and sand holes.
- A stone absorbing less water is stronger and more durable.
- The surface of the freshly broken stone should be bright, clean and sharp and should show the uniformity of texture without loose grains.
- It should be free from any dull chalky or earthy appearance.
- Stones showing mottled colour should not be used for face work. Free-stones are useful for carve work.
- Stones should have good weathering properties and only well-seasoned stone should be used in structural work. Seasoning is of special importance as far as limestone, sandstone, and laterites are concerned.
- The approximate life of granite, gneiss and good sandstone buildings is considered over 300 years while limestone and other weaker types of sandstones hardly last for 100 years.
Suitability of Stones
(1) Building on sea shore – granite and fine grained sandstone.
(2) Building in industrial town-granite and compact sand- stone.
(3) Bridge piers, docks and Breakwaters+granite and gneiss.
(4) Road metal-granite and basalt.
(5) Railway Ballast-sandstone, quartzite and compact lime- stone.
(6) For fire resistance-compact sandstone
2) Bricks – as construction and building materials
Bricks are blocks of tampered clay molded to suitable shapes and sizes while still in a plastic condition, dried in sun and burnt if desired so as to make them more strong, hard and durable.
Brick moulds are about 1/10th larger than the required size of the brick to allow for shrinkage on burning. The length of the brick is equal to twice the width plus the mortar joint. Brick shall be hand or machine moulded.
- They should be free from cracks and flaws and nodules of free lime.
Classes of bricks.
Depending upon their quality bricks can be classified into three classes.
(a) Class I Bricks:- They shall have a uniform color, shall be thoroughly burnt but not overburnt and shall have plane rectangular faces with parallel sides and sharp straight right-angled edges. They should have a fine compact and uniform texture and emit a clear ringing sound when struck.
(b) Class II Bricks:- They shall have uniform color and may be slightly overburnt. The bricks may be slightly distorted and have round edges. emit a clear ringing sound when struck. They should have a fine compact, uniform texture and emit a clear ringing sound when stuck.
(c) Class III Bricks:- They may be slightly overburnt or under- burnt. They may be distorted and have round edges. The defect in uniformity and shape shall not be such as to cause difficulty in obtaining courses with their use.
Composition of earth for bricks.
Good brick-earth is roughly constituted of about 60% silica and 20% alumina (clay). Oxides of calcium, iron, sodium, potassium, magnesium, and manganese form the remaining 20%. Functions of constituents are given below.
- Silica or sand:- It is present either free as sand or in combination as silicate of alumina. Silica is infusible except at very high temperature but in the presence of alumina in nearly equal proportion and the oxide of iron, it fuses at lower temperatures. Unlike silicate of alumina, its presence in clay produces hardness, resistance to heat, durability and prevents shrinkage and warping. Excess of it makes the bricks brittle.
- Alumina or clay:- It is a tenacious finely-grained mineral compound present in brick earth. It is plastic when wet and is capable of being moulded to any shape. On drying it loses its elasticity and becomes hard, shrinks, warps and cracks. Burning causes the fusion of its constituents thereby making it homogeneous, harder and stronger.
- Lime:- When present in small quantities in the finely divided state it reduces shrinkage of bricks and acts as a flux causing silica to melt. It results in binding the particles of brick together resulting in greater strength of bricks. Excess of lime causes the brick to melt and lose its shape.
- Magnesia:- In the presence of iron, it gives a yellowish tint to the bricks. It should not be present in excess. However, the presence of a small quantity of manganese with an iron will give the brick darker or even black colour.
- Oxide of iron:- In the presence of silica and alumina, it helps the fusion of brick particles. It also influences the colour of brick. It produces a tint varying from light yellow to red, depending upon the percentage of iron present in the clay. Excess of it makes the colour dark blue. It should not be present in the form of iron pyrite.
3) Cement – as construction and building materials
Commonly used cement for normal construction work is known as ordinary Portland cement. However, for use under specific conditions variety of cement are available these days.
Its quick setting, strength, and ease with which it can be used under a variety of conditions has revolutionized the concept of construction and made it the most popular binding material. On setting, the color of cement resembles the color of rocks available Portland in England and hence, the name of this cement has been given as Portland cement.
Composition of ordinary Portland
Cement Approximate composition is as follows:
- 20 to 25% Silica
- 4 to 8% Aluminium oxide
- 60 to 65% Calcium oxide –
- 2 to 4% Ferrous oxide
- 1 to 3% Magnesium oxide
Different kinds of Cements
Besides Portland cement, following are some important types of cements manufactured to suit the diffrerent requirements.
Quick Setting cement
It sets faster than the ordinary Portland cement. Its initial setting time is 5 minutes and the final setting time is 30 minutes.
It is used for making concrete that is required to set early as for laying underwater or in running water.
Initial setting time is very little there is always the danger of concrete having undergone initial set during mixing and placing. As such this cement is used only in exceptional circumstances.
High early strength or Rapid hardening cement
This cement gains strength faster than ordinary cement. Ita initial and final setting times are the same as those of ordinary cement. It contains more tri-calcium silicate and is more, finely ground. It gives out more heat while setting and is as such, unsuitable for mass concrete work. It is used for such structures are subjected to loads early, for example, repair of roads and bridges, etc. It is more costly than ordinary cement.
High alumina cement
It is together a mixture of Bauxite and limestone in correct proportions and at high temperature. The resulting product is ground finely. It develops strength rapidly. It is black in color and resists well the attack of chemicals especially of sulfates and of Sea Water. its ultimate strength is much higher than that of ordinary cement. its initial setting time is more than 2 hours and the final set takes place immediately thereafter. Most of the heat is given out by it in the first 10 hours as a result of which it can be conveniently used in freezing temperatures but is used in thin layers in normal temperature.
Low heat cement
The heat generated by cement while setting may cause the structure to crack. The heat generated is controlled by keeping the percentage of Tricalcium aluminates and of Tricalcium silicate low. Its initial and final setting times are nearly the same as those for ordinary cement but the rate of its developing strength is very slow.
It is not very suitable for use in ordinary structure as this will prolong the shuttering and also prolonged curing will have to be done.
Blast furnace cement
To get this cement 65% blast furnace slag obtained from ironworks is ground with clinker of ordinary cement. A little gypsum is added to the clinker and slag at the time of grinding. Its rate of hardening is slow otherwise the rest of its properties are similar to those of ordinary cement. Because of the lower heat evolution, it is more durable.
Air entraining portland cement
It is ordinary cement, mixed with small quantities of air entraining substances at the time of grinding. Usual air entraining materials used are resin oils, fats, vinsol resin, etc. Vinsol resin and dares are most commonly used. These materials have the property of entraining air in the form of a fine air bubble in concrete. These bubbles render the concrete more plastic, more workable and more resistance to freezing.
It is cement with pure white color and has the same properties as those of ordinary cement. Greyish color of ordinary cement is due to iron oxide. This cement is manufactured from white chalk and clay free from iron oxide. For burining, this cement, oil fuel should be used instead of coal. It is much more costly than ordinary cement.
By mixing suitable pigments ordinary portland cement could be given red or brown color. For other colours 5% to 10% of pigments are ground with white cement. Pigments used in cement should be chemically inert and also durable so as not to fade due to the effect of light, sun or weather.
Pozzolana cement is produced either by grinding together cement clinker and Pozzolana or by intimately and uniformly blending portland cement and fine Pozzolana. This cement has similar properties as the ordinary Pozzolana cement produces less heat of hydration and offers greater resistance to the attack of aggressive waters or sulphate. It also reduces the leaching of calcium hydroxide liberated during the setting and hydration of cement. This cement is particularly useful in marine works and also in mass concrete structures.
This cement takes a little longer than ordinary cement to gain strength. It is therefore recommended that when pozzolana cement is used in R.C.C works, the centering be left in position a little longer than in the case of ordinary cement. The ultimate strength of this cement is more than that of ordinary cement but initial and final setting times are the same.
How to Store Cement on site?
Cement if comes in contact with moisture, sets. Therefore in Its storage care should be taken to keep cement away from moisture.
Following precautions should be taken in storing cement.
- Walls, roofs, and floors of the cement store should be completely waterproof and dry.
- Doors and windows should be properly fitted and should be kept shut
- Cement bags should not directly be stored on the floor but wooden planks should be put on the floors first and the cement bags should be stored over them.
- Each incoming new consignment should be stacked Separately. This would help in using cement in the same order as it arrives, thereby avoiding dead storage.
- Bags should be piled close together and piled in beader stretcher fashion and each slake being not more than 15 bags high.
4) Aggregates – as construction and building materials
Aggregates are inert materials. They are used by mixing with binding material like cement, lime or mud, in the preparation of mortar or concrete Depending upon the size of their particles the aggregates are classified as fine aggregates, coarse aggregates, and cyclopean aggregates.
Most commonly used fine aggregate are sand, crushed stone, ash, and cinder. If the aggregate passes through 4.75 mm meshes and entirely retained on 0.15 mm, it is said to be a fine aggregate.
Aggregate whose particles are bigger than 475 mm but smaller than 75 cm s known as coarse aggregate. Stone, ballast, gravel or shingle, brick ballast, breeze, and clinker are the commonly used coarse aggregates. Stones that are free from undesirable mineral constituents and are not soft or laminated are broken and screened to have stone ballast. It is an excellent aggregate.
Mortar is a mechanical mixture in varying properties of a binding material like lime or cement and an inert material like sand, cinder, etc. Mortars are of three types
(a) Cement mortar
(b) Lime mortar and
(c) Cement lime mortars or composite mortar
Besides these mortars, there is mud mortar also which is used in the construction of kachha houses. We will not give much notice to the mud mortar.
Cement mortar can be mixed by hand but a lime mortar and composite mortar should be ground mechanically. The object of grinding mortar is to crush particles of unslaked lime if any, so, as to ensure their slaking and to make an intimate mixture of the binding material and the inert material.
Cement mortars are somewhat harsh and to improve their workability, 10% of the cement in cement mortar is often replaced by lime.
Mortar are used as a binding materails in stone or brick masonry, or concrete and as a covering materlal to walls in the form of plaster to provide a smooth, hard and decorative surface.
6) Concrete – as construction and building materials
Concrete is an artificial compound generally made by mixing lime, cement mortar wuth some hard materials such as broken stone, gravel shingle, broken bricks, slag, breez, burnt clay, etc. The mortar used in concrete is called matrix and the hard briken materaiks is known as aggregate.
Aggregate should not have smooth rounded pieces of stone but should have angular and rough pieces. Angular pieces fit into one another better. The aggregate should be thoroughly soaked in clean water before it is mixed with the mortar for concrete, otherwise, it will suck moister of the matrix and thereby, greatly reduce its strength. The size of aggregate differs greatly to the nature of the work. So, for different structure different sizes of aggregate should be used.
The natural it artificial mixture in which bitumen is associated with inert minerals matter is known as asphalt.
There are two varieties of asphalt.
- Natural asphalt and
- Residual asphalt.
A crystalline solid or viscous material having adhesive properties. It is derived from petroleum either by natural or refinery process, substantially soluble in carbon disulphide, but are usually made as end products from distillation of or as extract from selected petroleum oils.
These are the substances used for binding the surface of wood, metal, plastics and glass. Adhesives are classified into two categories.
1) Organic adhesives
2) Synthetic adhesives.
10) Glass – as construction and building materials
It is manufactured by fusing together in a pot or tank furnace an intimate mixture of one or more of oxides of silicon, boron or phosphorous and one or more of the basic oxides of soda potash, lime and magnesia and a tittle broken glass.
The product is cooled rapidly to avoid formation of crystals. Its melting point is from 850 to 950°C. It is hard, brittle and transparent materials having a very wide field of application.
Types of glasses are described below
It is stronger than sheet glass and also more transparent. It is made in thickness varying from 3 to 32 mm (approximately). It is ground and polished.
Flat drawn sheet glass
This is most commonly used glass for engineering purposes. This types of glass has fire finished surface and as the two surface parallel, there is always a certain degree of distortion of vision and reflection.
This glass is made with welded wire mesh embedded in its body to prevent it from shattering. It is available in 6’5mm thickness.
Laminated safety glass
Two or more plates of glass with interlayers of touch transparent plastics are bounded tightly together with the aid of heat and pressure so that even though the laminated plate is broken, practically no part of the glass will fly off and no sharp splinter or cutting edge will be exposed to inflict injuries. This types of glass are used mainly in vehicles.
It is fitted in windows to prevent heat loss. This glass consist of two or more hermetically sealed sheet
, separated by 6 to 12 mm off hydrated air.
Heat absorbing glass
It has a bluish green color and has the property of absorbing the infra-red rays of the sun. “Colorec” glass is one if such glasses.
It is a clear sheet of polished plate glass on the back of which is precipitated layers of a solution of silver nitrate and ammonia. The back of the layer is protected from dampness with a coat of shellac or varnish and two cats of lead or of tar paint.
11) Plastics – as construction and building materials
The term plastic denotes synthetic organic polymers. They are prepared from resins (natural or synthetic) with or without fillers, plasticizers, pigments or hardeners, etc. It is capable of bringing moulded to any shape in some stage of its manufacture. Wax, shellac, bitumen, pitch rubber, etc. are some of the natural resins used in the manufacture of plastics. Synthetic resins are prepared from raw materials in laboratories. These do not depend upon the natural resources of a country and their properties can be changed as desired by making adjustments in their constituents.
Plastic can be divided into two principal classes.
(1) Thermosetting, and
Thermosetting materials are either originally soft or liquid or they soften once upon heating. But upon further heating, they harden permanently. Phenol formaldehyde, melamine formaldehyde, Alkyd, and urea formaldehyde are some of the thermosetting plastics.
The thermoplastic may be softened by heating and hardened by cooling any number of times without changing the properties of the materials. Crylucs, polyethylene chloride, and polystyrene are some of the thermoplastic materials.
12) Timber – construction and building materials
Stone and timber are the oldest building materials known to mankind. Until the industrial revolution and the adoption of cast iron as a building frame, timber was unchallenged as the only material to be employed as building and structural material. With the development of synthetic adhesives and improved connectors, timber is, fast regaining its lost position as primary structural materials.
The timber is used for making furnitures, doors, and windows, flooring, roofing, beam, and column, etc.
Classification of Timber
Botanically the trees can be classified in two groups.
These trees are also called outward growing trees. All the commercial timber used for building purposes. is obtained from this class of trees.
These trees are also called inward growing trees. Palm and bamboo are examples if endogenous trees. Even though the stem of trees of this class is light tough yet it is too flexible and slender to furnish material suitable for Engineering works, with the exception of Bamboo.
Paints are the most essential materials used in construction and building materials for decorative purpose. It is a mixture of solid and liquid and is used to cover surface for decorative and preservative purpose. The solid is the pigments or base, and the liquid the medium or vehicle to enable the solid particles to be applied to the surface.
14) Metals – as construction and building materials
Metals are grouped into two classes (i) Ferrous metals and (ii) non-ferrous metals.
Ferrous metals have iron as their principal constituent whereas non-ferrous metals are those whose principal element is not iron.
Ferrous Metals Ferrous metals comprise three general classes :
(1) Cast iron
(2) Wrought iron, and
All of them are prepared by conversion of iron ores into pig iron and then subsequently metallurgical. treatments.
Iron products are classified as follows:
It is the product obtained by reducing iron ores in the blast furnace. Carbon content ranges from 2.5 to 4.5 percent. The iron is cast into rough bars termed ‘Pigs’.
It is remelted pig iron after being cast or about to be cast in final form. Its composition need not necessarily differ from pig iron. Cast iron is not malleable at any temperature. Malleable cast iron can be produced by rendering malleable, partly or wholly by annealing.
This is the purest form of iron used for construction and building materials. It is a form of iron aggregated from a solidifying mass of pasty particles of highly refined metallic iron, with which, without subsequent fusion, is incorporated a minutely and uniformly distributed a quantity of slag. The carbon content is from a trace to 0.25% and slag from 0.6 to 3%. It is malleable initially but will not harden rapidly when rapidly cooled due to low carbon content.
It is a type of Iron of extremely low carbon has been cast from a molten condition.
It is an alloy of iron and carbon which is cast from molten mass, It is malleable in some range of temperature and may not harden upon sudden cooling. The carbon content is usually less than 1.5% but not greater than 2%. Steel which owes its properties due to carbon is known as “carbon steel”. and others that have distinct properties due to elements other than carbon are termed as “Alloy steels”.
I hope this article on “Different construction and building materials used for all types of structure” remains helpful.