Course Code: CE – 115

Course Credit: 3

There are no secrets to success. It is the result of preparation, hard work, and

learning from failure.

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Engr. Abdur Rehman

(M.Sc. Urban Infrastructure Engineering, UET

Peshawar),

Permanent Faculty Member,

SARHAD University Of Information & Technology

(SUIT), Peshawar.

Visiting Faculty Member

Peshawar College of Engineering (PCE), Peshawar.

To develop an understanding of the properties, uses and behavior of the building materials, standards for material quality, various tests on materials.

To develop the basic understanding of construction techniques and methods of building construction with particular reference to R.C. work, brick work, flooring, damp-proofing, roofing and stairs.

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BRICKS, BLOCKS & TILES

STONES

AGGREGATE

WATER, LIME, CEMENT & TIMBER

PAINTS & VARNISHES

METALS

GLASS & PLASTICS

MASONRY

CONSTRUCTION

Materials of Construction by R. C. Smith and C. K. Andres, ISBN:0070585040, McGraw Hill. January 1987 (Latest Edition).

Building Construction Vol. I to Vol. IV by Mckay (Latest Edition).

Building Construction by Mitchall (Latest Edition). Building Construction by Huntington (Latest Edition). Civil Engineering Materials by Neil Jackson (Latest Edition). Construction Materials by P. D. Domone, University

College, London (Latest Edition). Materials of Construction by Z. H. Syed (Latest Edition). Fundamental of Building Construction: Material and

Methods, by Edward B. Allen, (Latest Edition).

LECTURE # 01

An artificial masonry unit in the form of a rectangular block of prepared clay is called a brick

Bricks are manufactured by molding brick earth in rectangular blocks of uniform size and shape and then by drying or burning these blocks in a suitable clamp or kiln.

The bricks simply dried in the sun are known as dried or kacha bricks, and those burnt in the clamp or kiln are known as burnt or puccabricks. Bricks are burnt to provide them strength and durability

Brick earth: Earth used in manufacture of brick (20-30% clay, 35-50% sand, 20-35% silt, 1-2% of lime, oxide of iron, manganese etc)

A concrete block is primarily used as a building material in the construction of walls. It is sometimes called a concrete masonry unit (CMU). A concrete block is one of several precast concrete products used in construction. The term precast refers to the fact that the blocks are formed and hardened before they are brought to the job site. In use, concrete blocks are stacked one at a time and held together with fresh concrete mortar to form the desired length and height of the wall.

The production of concrete blocks consists of four basic processes: mixing, molding, curing, and cubing.

Mixing

The sand and gravel are stored outside in piles and are transferred into storage bins in the plant by a conveyor belt as they are needed. The portlandcement is stored outside in large vertical silos to protect it from moisture.

As a production run starts, the required amounts of sand, gravel, and cement are transferred by gravity or by mechanical means to a weigh batcher which measures the proper amounts of each material.

The dry materials then flow into a stationary mixer where they are blended together for several minutes. There are two types of mixers commonly used. One type, called a planetary or pan mixer, resembles a shallow pan with a lid. Mixing blades are attached to a vertical rotating shaft inside the mixer. The other type is called a horizontal drum mixer. It resembles a coffee can turned on its side and has mixing blades attached to a horizontal rotating shaft inside the mixer.

After the dry materials are blended, a small amount of water is added to the mixer. If the plant is located in a climate subject to temperature extremes, the water may first pass through a heater or chiller to regulate its temperature. Admixture chemicals and coloring pigments may also be added at this time. The concrete is then mixed for six to eight minutes.

Molding

Once the load of concrete is thoroughly mixed, it is dumped into an inclined bucket conveyor and transported to an elevated hopper. The mixing cycle begins again for the next load.

The hopper conveys the material to the block machines and from there it is conveyed to the molds. When the blocks are full, the concrete is compacted, supplemented by air compaction and vibration

The blocks are pushed down into a flat steel pallet and conveyed through conveyor belt along with the application of brushes over the blocks, to remove the loose material or dirt

Curing:

The blocks are conveyed to the curing racks. Each rack holds several hundred blocks. When the rack is full, it is moved into the curing kilns

The kiln is an enclosed room with the capacity to hold several racks of blocks at a time. There are two basic types of curing kilns. The most common type is a low-pressure steam kiln. In this type, the blocks are held in the kiln for one to three hours at room temperature to allow them to harden slightly. Steam is then gradually introduced to raise the temperature at a controlled rate of not more than 60°F per hour (16°C per hour).

Standard weight blocks are usually cured at a temperature of 66-74°C, while lightweight blocks are cured at 77-85°C. When the curing temperature has been reached, the steam is shut off, and the blocks are allowed to soak in the hot, moist air for 12-18 hours. After soaking, the blocks are dried by exhausting the moist air and further raising the temperature in the kiln. The whole curing cycle takes about 24 hours.

Another type of kiln is the high-pressure steam kiln, sometimes called an autoclave. In this type, the temperature is raised to 149-191°C, and the pressure is raised to 80-185 psi. The blocks are allowed to soak for five to 10 hours. The pressure is then rapidly vented, which causes the blocks to quickly release their trapped moisture. The autoclave curing process requires more energy and a more expensive kiln, but it can produce blocks in less time.

Cubing:

The racks of cured blocks is pushed out of the kiln and programmed for conveying new sets of fresh cubes for the kiln

The blocks pass through a cuber which aligns each block and then stacks them into a cube three blocks across by six blocks, by three or four blocks high. These cubes are carried outside with a forklift and placed in storage.

First class bricks:

Color is deep red, cherry or copper.

Surface is smooth and rectangular with parallel, sharp and straight edges.

It is free from flaws, cracks and stones.

It has uniform texture.

No impression should be left when scratched with nail.

Metallic or ringing sound should be produced when two bricks are struck.

Water absorption should be less than 20 percent of its weight when immersed in cold water for 24 hours.

Minimum crushing strength should be 10 N/mm^2.

It is used for pointing, exposed face work, flooring and reinforced brick work.

Second class bricks:

Small cracks and distortions are permitted.

Water absorption should be less than 22 percent when immersed in water for 24 hours.

Crushing strength should be between 7-10 N/mm2.

It is used for all purposes.

Third class bricks:

These are under burnt bricks.

These are light in color.

These produce dull sound when are struck to each other.

Water absorption should be less than 24 percent when immersed in water for 24 hours.

These are used for building temporary structures.

Fourth class bricks:

These are over burnt bricks.

These are badly distorted.

These are brittle in nature.

Ballast of bricks are used for foundation and floors in lime, concrete and road material.

Compressive strength: Fairly obviously, this is the ability of the masonry unit (brick or block) to resist crushing loads, eg the weight of the roof that the wall is supporting, plus the weight of the wall itself. The designer of the structure needs to be sure that the masonry unit will be able to carry the load being placed upon it, including any live loads.

Salt attack resistance: In some situations, bricks can be attacked by salts from ground water, swimming pools , spas etc. How resistant a given brick is to the effects of salt crystallization will depend on things like the porosity of the paver and the strength of the material the paver is made from, as well as the concentration and type of salt, and moisture and temperature conditions.

Moisture expansion: All fired clay bricks expand slowly after their manufacture, by taking up moisture out of the atmosphere. The expansion continues for many years, and needs to be taken into account in building design. To predict the long-term expansion, a brick length can be accurately measured before and after a laboratory steam treatment and the change in length used to estimate how much the brick will expand in 15 years. These expansion characteristics depend on the clays used in making the bricks, and on the manufacturing process itself.

Potential to effloresce: Efflorescence is a deposit of salts, usually white, on the surface of bricks and blocks after being laid. The salts usually come from ground water or out of the mortar, but may come from within the masonry units themselves.

This test predicts the likelihood that the units will display such unsightly deposits from salts that they already contain.

Water absorption: A standard soaking-in-water test can determine the porosity of bricks and blocks, which can then be used as an indication of the potential for the development of problems related to the penetration of salts and other materials into the units, such as salt attack and efflorescence.

Initial rate of absorption: The Initial Rate of Absorption test measures the amount of water a dry brick can soak up during the first minute of contact with water.To get the best bond, it’s important to match the “suction” of the brick to the water-retaining properties of the mortar. If the initial rate of absorption of the brick is too high for the mortar that’s being used, the mortar may dry out too quickly and stiffen before the next course can be laid. If it’s too low, not enough cementitiousmaterial is drawn up into the brick pores. In either case, the bond strength will suffer.

Color: The color of good brick should beuniform. It may deep red, cherry or coppercolored

Shape: Bricks should be uniform in shape withsharp straight right angled edges.

Size: Size of the bricks should be standard asprescribed by Indian standards. [19cm x 9cm x9cm]

Soundness: A good brick should give metallicringing sound when struck with another brick.'

Hardness: A good brick should be sufficientlyhard which can be tested by a finger nail. Nomark should be left on the surface of the brickwhen scratched with thumb-nail.

Crushing strength: The crushing strength of abrick should not be less than 35 kg/sq.cm

Water absorption: First class brick should notabsorb water more than 20% of its dry weightwhen soaked in water for 24hrs.

Structure: A good brick should show fine,compact and uniform structure in broken form.

Fire resistance & Thermal conductivity: Itshould have thermal conductivity. A goodbrick should have adequate fire resistance.Ordinary brick can resist temperature upto12000C

Strength: Bricks should not break whendripped on hard ground from a height of about1m.

Durability: A good brick should be able toresist the effects of weathering agencies liketemperature, rain, etc.

A tile is a manufactured piece of hard-wearingmaterial such as ceramic, stone, metal, oreven glass, generally used for covering roofs,floors, walls, showers, or other objects such astabletops. Alternatively, tile can sometimesrefer to similar units made from lightweightmaterials such as perlite, wood, and mineralwool, typically used for wall and ceilingapplications.

The word is derived fromthe French word tuile, which is, in turn, fromthe Latin word tegula, meaning a roof tilecomposed of fired clay.

Tiles are most often made of ceramic, typicallyglazed for internal uses and unglazed forroofing

Tiles are manufactured in the following stages:

Raw Materials:

The raw materials used to form tileconsist of clay minerals mined from the earth's crust,natural minerals such as feldspar that are used tolower the firing temperature, and chemical additivesrequired for the shaping process. The minerals areoften refined or beneficiated near the mine beforeshipment to the ceramic plant.

The raw materials must be pulverized(crushed) and classified according to particlesize. Primary crushers are used to reduce largelumps of material. Either a jaw crusher orgyratory crusher is used.

The initial step in ceramic tile manufactureinvolves mixing the ingredients. Sometimes,water is then added and the ingredients arewet milled or ground in a ball mill. If wetmilling is used, the excess water is removedusing filter pressing followed by spray drying.The resulting powder is then pressed into thedesired tile body shape.

Secondary crushing reduces smaller lumps toparticles. Hammer or muller mills are often used.A muller mill uses steel wheels in a shallowrotating pan, while a hammer mill uses rapidlymoving steel hammers to crush the material. Rolleror cone type crushers can also be used.

A third particle size reduction step may benecessary. Tumbling types of mills are used incombination with grinding media. One of the mostcommon types of such mills is the ball mill, whichconsists of large rotating cylinders partially filledwith spherical grinding media.

Screens are used to separate out particles in aspecific size range. They operate in a slopedposition and are vibrated mechanically orelectromechanically to improve material flow.Screens are classified according to meshnumber, which is the number of openings perlineal inch of screen surface. The higher themesh number, the smaller the opening size.

A glaze is a glass material designed to meltonto the surface of the tile during firing, andwhich then adheres to the tile surface duringcooling. Glazes are used to provide moistureresistance and decoration, as they can becolored or can produce special textures.

Batching:For many ceramic products, including tile, the body

composition is determined by the amount and type of rawmaterials. The raw materials also determine the color of thetile body, which can be red or white in color, depending onthe amount of iron-containing raw materials used.Therefore, it is important to mix the right amounts togetherto achieve the desired properties. Batch calculations arethus required, which must take into consideration bothphysical properties and chemical compositions of the rawmaterials. Once the appropriate weight of each rawmaterial is determined, the raw materials must be mixedtogether.

Mixing and grinding:

The ingredients are weighed,they are added together into a shell mixer,ribbon mixer, or intensive mixer. A shell mixerconsists of two cylinders joined into a V, whichrotates to tumble and mix the material. Thisstep further grinds the ingredients, resulting ina finer particle size that improves thesubsequent forming process

Sometimes it is necessary to add water toimprove the mixing of a multiple-ingredientbatch as well as to achieve fine grinding. Thisprocess is called wet milling and is oftenperformed using a ball mill. The resultingwater-filled mixture is called a slurry or slip.The water is then removed from the slurry byfilter pressing (which removes 40-50 percent ofthe moisture), followed by dry milling.

Spray drying:

If wet milling is first used, the excesswater is usually removed via spray drying.This involves pumping the slurry to anatomizer consisting of a rapidly rotating diskor nozzle. Droplets of the slip are dried as theyare heated by a rising hot air column, formingsmall, free flowing granules that result in apowder suitable for forming.

Forming:

Most tiles are formed by dry pressing.In this method, the free flowing powder—containing organic binder or a low percentageof moisture—flows from a hopper into theforming die. The material is compressed in asteel cavity by steel plungers and is thenejected by the bottom plunger. Automatedpresses are used with operating pressures ashigh as 2,500 tons.

Several other methods are also used where the tile body is in a wetter, more moldable form. Extrusion plus punching is used to produce irregularly shaped tile and thinner tile faster and more economically.

Ram Pressing:

Ram pressing is often used forheavily profiled tiles. With this method, extrudedslugs of the tile body are pressed between twohalves of a hard or porous mold mounted in ahydraulic press. The formed part is removed byfirst applying vacuum to the top half of the moldto free the part from the bottom half, followed byforcing air through the top half to free the top part.Excess material must be removed from the partand additional finishing may be needed.

Pressure glazing:

Another process, called pressure glazing, has recently been developed. This process combines glazing and shaping simultaneously by pressing the glaze (in spray-dried powder form) directly in the die filled with the tile body powder. Advantages include the elimination of glazing lines, as well as the glazing waste material (called sludge) that is produced with the conventional method.

Drying:Ceramic tile usually must be dried (at

high relative humidity) after forming, especially ifa wet method is used. Drying, which can takeseveral days, removes the water at a slow enoughrate to prevent shrinkage cracks. Continuous ortunnel driers are used that are heated using gas oroil, infra red lamps, or microwave energy. Infrareddrying is better suited for thin tile, whereasmicrowave drying works better for thicker tile.Another method, impulse drying, uses pulses ofhot air flowing in the transverse direction insteadof continuously in the material flow direction.

Glazing:After a batch formulation is calculated, the

raw materials are weighed, mixed and dry or wetmilled. The milled glazes are then applied using one ofthe many methods available. In centrifugal glazing ordiscing, the glaze is fed through a rotating disc thatflings or throws the glaze onto the tile. In thebell/waterfall method, a stream of glaze falls onto thetile as it passes on a conveyor underneath. Sometimes,the glaze is simply sprayed on. For multiple glazeapplications, screen printing on, under, or between tilethat have been wet glazed is used. In this process, glazeis forced through a screen by a rubber squeegee orother device.

Firing:

After glazing, the tile must be heatedintensely to strengthen it and give it thedesired porosity. These kilns move the wareson a roller conveyor. Firing times in roller kilnscan be as low as 60 minutes, with firingtemperatures around 2,102 degrees Fahrenheit(1,150 degrees Celsius) or more.

Inorganic, non-metallic materials made fromcompounds of a metal and a non metal.Ceramic materials may be crystalline or partlycrystalline. They are formed by the action ofheat and subsequent cooling. Clay was one ofthe earliest materials used to produce ceramics,as pottery, but many different ceramicmaterials are now used in domestic, industrialand building products. Ceramic materials tendto be strong, stiff, brittle, chemically inert, andnon-conductors of heat and electricity, but theirproperties vary widely.

Crystalline ceramics:

Crystalline ceramic materials arenot amenable (willing) to a great range ofprocessing. Methods for dealing with themtend to fall into one of two categories - eithermake the ceramic in the desired shape, byreaction in situ, or by "forming" powders intothe desired shape, and then sintering to form asolid body.

Non-crystalline ceramics:

Non-crystalline ceramics, beingglasses, tend to be formed from melts. Theglass is shaped when either fully molten, bycasting, or when in a state of toffee-likeviscosity, by methods such as blowing to amold. If later heat-treatments cause this glass tobecome partly crystalline, the resultingmaterial is known as a glass-ceramic.

Thank You!

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