all the engineering structures are made from some materials these materials are know as engineering...

All The engineering Structures are made from some materials

These materials are know as engineering materials; building

materials or materials of Construction .

No material, existing in the universe is useless. Every material has its own field ofapplication

StoneStone

StoneStoneAn engineer has to be conversant with the An engineer has to be conversant with the

properties of most of them .properties of most of them .stone, bricks, timber, steel, lime, cement, stone, bricks, timber, steel, lime, cement,

and metals are some commonly used and metals are some commonly used materials by a civil engineer .materials by a civil engineer .

In order to carry out safe constructions , some standards for the materials to be used are fixed

stone :stone :

RockRock is the term is the term

used to name a solid used to name a solid

portion of the earth's portion of the earth's

crust . crust .

It has no definite It has no definite

shape and chemical shape and chemical

composition . composition .

It is generally very It is generally very

big in site .big in site .

The rocks have one The rocks have one

or more than one or more than one

materials .materials .

Rock and stone

stone :stone :

Rock and stone

stone :stone :

Stone :Stone : The stone The stone is always obtained is always obtained from rock, The rock from rock, The rock quarried from quarried from quarries is called quarries is called stone .stone .Quarried stone may Quarried stone may be in form of stone be in form of stone blocks, Stone blocks, Stone aggregate , stone aggregate , stone slabs, stone lintels , slabs, stone lintels , Stone flags ,etc . Stone flags ,etc .

Rock and stone

stone :stone :

Rock and stone

Classification of rocksClassification of rocks

1. Geological classification

2. Physical classification

3. Chemical classification

4. Classification based on stone

hardness:

StoneStone

Classification of rocksClassification of rocksAccording to this classification stone

may be classified As soft, medium, hard and very soft, medium, hard and very

hardhard.-Very hard rocks as Granite, Trap and

Taconite.-Hard rocks as Granite, Basalt, Gravel

and Quartzite.- Medium rocks as Dolomite and Lime

Stone.- Soft rocks as Talc, Gypsum and Sand

stone.

StoneStone

StoneStone

Uses of stone following are the various uses , of stones

1.For masonry work

2.for lintels and vertical columns

3.for covering floors of building

4.for paving of roads and foot paths

5.As a covering material for buildings.

StoneStone

Uses of stone following are the various uses , of stones

6.for the construction of roads in form of boulders and aggregate

7.as an aggregate in cement as well as lime concretes

8.Base material for water and sewage filters.

9.For the manufacture of cement and lime.

10.In the construction of masonry dams , stones of good quality and durability are of vital importance.

StoneStone

StoneStoneNatural bed of Natural bed of stonestone

The plane along which stones can be easily split is known

as natural bed of natural bed of stonestone

In stone masonry work , the stone

should be used in such away that the

direction of applied load is

perpendicular to the natural bed of the

stone .

Walls

B

Cornice

Arch

-In the case of the walls the position of the

stone blocks should be same in which they

were originally deposited .

This position gives maximum strength to

the stone work in the walls .

-In the case of arches , the bedding plane

should be radial and at right angles to the

face of the arch .

-In the case of cornices the bed should be

vertical .

StoneStone

Seasoning of stones :

-In makes the stone hard and compact , by

exposing the stone to open air for a period

of six to twelve mouths .

All the stones should be seasoned before

they are used in structural work .

StoneStone

StoneStone

Characteristics and qualities of good building stone :

1.The stone should be easily and

economically obtainable in bulk .

2.The stone should be hard, strong and

durable .

3.It should weather well.

4.It should have fine compact texture .

StoneStone

Characteristics and qualities of good building stone :

5.It should be capable to withstand

the effects of smoke and acidic

atmosphere.

6.The stone should be free from soft

patches, flaws, cavities and cracks .

7.It should be well seasoned and

easily workable .

StoneStone

Tests for stones:Tests for stones:

Building stones are required to be tested

for their different properties before they

may be recommended for any specific case.

1-Acid test:

2- Water absorption test .

3- Impact test .

4- Crushing test .

5- Hardness test .

StoneStone

Acid test:

This test is carried out on sand stone .

In this test , a sample of stone about

100gm is taken and put in a solution having

1% strength of hydrochloric acid for seven

days . After this the specimen is taken out

and its surface examined .

StoneStone

Natural (Rock) stoneNatural (Rock) stoneStone classification:

•According to its contents •According to place which refer to•According to its texture

Natural stone properties (advantages) Natural stone properties (Disadvantages)Stoning Manufacturing Stone construction:Stone finishing

Selection of Stone as building Material • Importance of Preliminary Investigation.-

– When an important masonry structure is to be built, it is essential to select a stone that is strong and durable. Probably nothing in engineering construction is so neglected as the preliminary inspection of building stone.

• Inspection of Stone at Quarry• Careful inspection at the quarry will frequently reveal much information

regarding the durability and uniformity of the stone. Exposed quarry faces will sometimes indicate the weathering properties of the stone, as well as its liability to disintegration caused by moisture and running water containing injurious acids and alkalis.

• Inspection of Stone in Buildings.- If, after years of exposure in the atmosphere of an industrial city situated in the temperate zone, the building stone shows no disintegration and has retained its original luster and color, except for the soil of dust and smoke stains, it certainly can be considered of the best structural value for building purposes. If a stone from a certain quarry shows poor weathering qualities in a structure, an investigation should be made to determine whether the best grade from the quarry has been used, before the product of the quarry is condemned.

21

• Laboratory Investigation.- When the stone to be used is from a new quarry, the characteristics of the product are little known, and this investigation is then necessary. The laboratory investigation of stone usually consists of chemical analysis, microscopic examination, and mechanical tests.

22

Tests on Stones: • Specific Gravity test.• Amount of water absorbed ( Absorption Test) • Fire resistance ( Fire tests) • Abrasion and Hardness tests • Resistance to Acids• Color • Compressive Strength • Cohesive Properties ( Barad’s test) • Resistance to Acids ( Acid tests) • Structure Crystalline or not ( Smith’s test)•

23

Preservation of Stones: • Pointing ( Struck or raised) • Plaster • Paints oils and chemical solutions

• Linseed oil boiled • Melted paraffin

• Ransome’s process • Potassium or Sodium Chloride is fed into the pores of stones by repeated application

• Use of Solution of Barium Hydrate (Bayrta) in atmosphere charged with Carbonic and Sulpur acids • Szerelmeys Stone Liquid

• Silicates of Sodium and potassium applied with chlorides of Calcium and Barium

• Cleaning and washing etc.

24

QuarryingQuarrying is a form of mining similar to open-pit mining, involving the

extraction of useful natural stone from a man-made open pit called a quarry by cutting, digging, or blasting.

Rock is either quarried as solid blocks or slabs, or crushed and broken. Minerals produced from quarries include coal, clay, gypsum, marble, gritstone, limestone, sand, and sandstone.

The industry is distinguished by dimension-stone and crushed-stone quarrying. The dimension-stone process involves the quarrying of solid blocks or slabs of stone used for decorative and ornamentation purposes. In the crushed-stone process, materials such as granite, limestone, sandstone, and basaltic rock are crushed for use in concrete aggregate or road stone for road construction.

The method used to quarry stone depends on the stone’s composition, hardness, structure, cleavage, and other physical properties. The characteristics and placement of rock mass deposits is also an important consideration. For stone that is deposited in relatively accessible beds, hand tools such as drills, hammers, and wedges are employed. The demand for crushed rock such as limestone has actually led to the development of new kinds of quarrying techniques and quarrying is a less selective process than it used to be 25

Hardness of Stone - Hardness is the most important single factor for suitability of stone as building

material. - Hardness is measured by scratching of stone and compared with the following: - Talc: Easily scratched by the thumb nail - Gypsum and Rock salt: Can be scratched by Thumb nail - Calcites: Cannot be scratched by thumb nail but can be easily cut by knife. - Fluorite or Fluorspar: Can be cut with a knife but difficultly. - Apatetite: Can be cut only with difficulty with a knife. - Feldspar and orthoclase: Can be cut only with great difficulty with a knife in

thin edges. - Quartz: Cannot be scratched by steel but scratches glass- Topaz: Corrundun or SapphireDiamond. The harness factor

26

Characteristics of Building Stones:

- Availability: To be reasonably available near construction sites. - Durability: Wind, rain and temperature and pressure affect the

strength of rocks. The best way is to observe the old buildings. - Strength against crushing: The texture and specific gravity

affect the crushing strength of stones. Stones with even texture and specific gravity more than 2.7 is considered as strong enough.

- Appearance and colour: Stones with uniform colour are durable. Good weathering stone should always be free flaws and clay holes.

-

27

- Texture, Hardness and Toughness: Stones with homogenous and crystalline texture are coarse grained hard and compact. Stones quarried from greater depths are durable and suitable for building construction as it has been compacted. Harness combined with toughness are specially important for stones used in road metal, floor slabs, door steps, paving blocks etc.

- Porosity and Absorption: The volume of pores to the total volume of stone. Clayey verities have 5-8% of their weight. Porous stones shouldn't be used in the facing of the buildings.

28

-

Facility of Working: Economy seems to be an important consideration. The cost of dressing the stone is a major component.

Weight: Heavy stones are suitable for marine works and retaining walls, whereas light stones are best adopted for aches.

Fire resistance: The difference in temperature between exposed surface and inner surface of stone may cause its disintegration . Traps and basalts are good fire resisting but granite disintegrate quickly when exposed to temp difference due to free quartz as at 600 C quartz expands suddenly and disintegrate granite. Limestone disintegrate at 800 C. Sandstones are good in fire resisting.

Seasoning quality: Freshly quarried stones contains some moisture and hence it can be cut easily. Hence it must be dressed roughly as early as possible. Its final dressing is done at site.

29

Name of Stone Porosity= (Volume of water absorbed /Volume of stone)*100

1. Marble Practically Nil

2. Trap or Basalt 1%

3. Granite 0.5-2%

4. Good Sandstone 8% -10%

5. Lime Stone 14-16%

• The sap one must be removed which is called seasoning and the stones are placed in the open for 6-12 months. But at site this precaution is not taken.

• Natural Bed: The original position of the stone during its formation is called its bed. The natural bed of sedimentary rocks can be easily identified. Stones should be placed at right angle to its bed. The lamination of the stone must be at right angle to the load.

• Appearance• The appearance of stone is often a matter of importance, especially in the face

work of conspicuous buildings.• In order that the appearance may be preserved, a good weathering stone should

of course be selected, free from flaws, clay holes, etc. All varieties containing much iron should be rejected, or they will be liable to disfigurement from unsightly rust stains caused by the oxidation of the iron under the influence of the atmosphere.

• Stones of blotched or mottled color should be regarded with suspicion. There is probably a want of uniformity in their chemical composition, which may lead to unequal weathering 30

Important Building Stones: Granite, Gneiss and SyeniteThe granites are massive rocks occurring most frequently as the central

portions of mountain chains. They are a hard, granular stone, composed principally of quartz, feldspar and mica, in varying proportions. When the stone contains a large proportion of quartz it is very hard and difficult to work. When there is a considerable proportion of feldspar the stone works more easily.

The color of the granite is principally determined by the color of the feldspar, but the stone may also be light or dark, according as it contains light or dark mica. The usual color of granite is either a light or dark gray, although all shades from light pink to red are found in different localities.

Gneiss (pronounced like nice) has the same composition as granite, but the ingredients are arranged in more or less parallel layers. On this account the rock split in such a way as to give parallel flat surfaces, which renders the stone valuable for foundation walls, street paving and flagging. Gneiss is generally taken for granite, and is frequently called by quarrymen stratified or bastard granite.

Syenite is a rock also resembling granite, but containing no quartz. It is a hard, durable stone, generally of fine grain and light gray color.

32

GraniteGranite

Non-porous, hard, strong, durableNon-porous, hard, strong, durable

Color RangeColor Range

Surface TexturesSurface Textures

SourcesSources

Primary UsesPrimary Uses

33

Polished Surface

Rough Texture

34

ShapeFlat to Round

35

Limestone & SandstoneLimestone & Sandstone

Porous, relatively weakPorous, relatively weak Color RangeColor Range Surface TexturesSurface Textures SourcesSources Primary UsesPrimary Uses

36

Limestone with Granite

37

Marble - Exterior Application

38

Slate Flooring

LimestoneThis name is commonly used to include all stones which contain lime, though

differing from each other in color, texture, structure and origin. All limestone used for building purposes contain one or more of the following substances, in addition to lime :

Carbonate of magnesia, iron, silica, clay, bituminous matter, mica, talc and hornblende.

There are three varieties of limestone used for building purposes, viz.: Oolitic limestone, magnesian limestone and dolomite.

Oolitic limestones are made up of small rounded grains (resembling the eggs of a fish) that have been cemented together with lime to form a solid rock.

Magnesian limestone include those lime stones which contain 10 per cent, and over of carbonate of magnesia.

Dolomite is a crystalline granular aggregation of the mineral dolomite, and is usually whitish or yellowish in color. It is generally heavier and harder than limestone.

All varieties of limestone are liable to contain shells, corals and fossils of marine animals, more or less pulverized. A limestone can be identified by its effervescence when treated with a dilute acid.

All kinds of limestone are destroyed by fire, although some varieties will stand a greater degree of heat without injury than others.

MarbleMarble is simply a crystallized limestone, capable of taking a good polish.The scarcity and consequent expense of good marbles have in the past

prevented them from being used in constructional work, except occasionally for columns. Most of the marbles obtained from the older quarries also stain so easily that they are considered undesirable for exterior work.

Since the rapid development of the Georgia and Tennessee marble quarries, however, stone from these quarries has been much used for exterior finish, and even for the entire facing of the walls. These marbles will probably be more extensively used for exterior work in the future, as they are exceedingly strong and durable and do not stain readily.

Nearly all varieties of marble work comparatively easy, and the fine-grained varieties are especially adapted for fine carving.

They generally resist frost and moisture well, and are admirably suited for interior decoration, sanitary purposes, etc., and in clear, dry climates make a splendid material for exterior construction.

The strength of marble varies from 5,000 to 20,000 pounds per square inch, and only when used for columns need its strength be considered.

40

SlateAlthough slate is not strictly a building stone, yet it is largely used for

covering the roofs of buildings, for blackboards, sanitary purposes, etc., and the architect should be familiar with its qualities and characteristics.

The ordinary slate used for roofing and other purposes is a compact and more or less metamorphosed siliceous clay. Slate stones originated as deposits of fine silt on ancient sea bottoms, which in the course of time became covered with thousands of feet of other materials and finally turned into stone.

"The valuable constituents in slate are the silicates of iron and alumina, while the injurious constituents are sulphur and the carbonates of lime and magnesia."

One of the most valuable characteristics of slate is its decided tendency to split into thin sheets, whose surfaces are so smooth that they lie close together, thus forming a light and impervious roof covering. These planes of cleveage are caused by intense lateral pressure, and are generally at very considerable though varying angles with the ancient bedding.

The most valuable qualities of slate are its strength, toughness and non-absorption.

41

Masonry• Masonry is a process of building with stone, brick, concrete masonry

units, and other similar material.• Stone is one of the oldest building materials. Most stonework today is

installed as non load bearing decorative surfaces on interior and exterior walls.

• Granite is hard and durable. Sandstone varies in hardness and durability. Limestone is a light grey stone (buildings and monuments in Washington, D.C.). Marble is less resistant to weathering and more prone to staining than granite. Slate is used for floor tile and roofing.

• Manufactured stone is made from lightweight concrete and resembles natural stone.

• Stone is used for fireplace surrounds, accent walls, and floor surfaces.

Mortar

• Mortar is a binding agent that binds masonry units together. It must be durable and water resistant. Mortar is made from Portland cement, masonry cement, hydrated lime, sand, and water.

• Ties are wire or sheet metal pieces used to join different wall material.

• Leads are corners of a masonry wall. They are laid first as a guide for laying the remainder of the masonry units between two leads.

• Mason’s line is a light strong cord that is stretched between leads as a guide for laying blocks between corners.

44

MortarMortar

Pre-packagedPre-packaged

Color rangeColor range

Testing / Testing /

SpecificationsSpecifications

CuringCuring

““Shelf” lifeShelf” life

• A brick is a block of ceramic (Clay) material molded to suitable shape and size and is used in masonry construction.

• After stone and clay, it is oldest construction material used for light and heavy structures.

• It has been regarded as one of the longest lasting and strongest building materials used throughout history.

• Quality of bricks depends on the parent material, finishing and quality of burning.

45

04/21/23 02:01 CE-115 Civil Engineering Materials 46


Length 9 inch

Height 3 inch

Stretcher

Frog

Width 4.5 inchHeader

Riser

Brick


Brick Mold

49

Classification of Bricks

Bricks are broadly classified in to two categories:1.Sun Dried bricks/Unburnt Bricks

2. Burnt bricks or pacca Bricks

Sun Dried bricks/Unburnt BricksThese bricks after molding have been dried in the

sun.These are used only for temporary and light

structures.

50

Classification of Bricks

• When exposed to rain or other climatical agents are readily disintegrated.

51

• After sun drying, these bricks are burnt in Kiln for certain period then cooled and removed from kiln and supplied to markets.

53

Burnt Bricks

54

These bricks are stronger and have larger compressive strength than unburt bricks.

These bricks are classified into four types:

1.First Class Bricks2.Second class Bricks3.Third class Bricks4.Over burnt Bricks

• These are well burnt and uniform color.• Its all faces are uniform, smooth and sharp.• These are very solid and are free from cracks

and flaws.• This is used for the construction of superior

work i-e heavy foundation and structures.• If it stuck against the same type of brick, good

metallic sound is obtained without any breeding.

55

First Class Bricks

• If it is fractured, the interior surface of the bricks shows the uniform textures.

• They do not absorb water of more than 15% of the dry weight.

• They have of the minimum crushing speed strength of 10.5N/mm2.

• Efflorescence presence is very little.

56

• This brick is used for sound work of permanent nature, construction of load bearing walls, facial work, reinforced brick work, pavements, walk-a-ways and flooring.

First class bricks Uses

57


First class bricks

• This kind of bricks are also well burnt but have reasonable smooth surface with fine hair cracks and mild distortion.

• They are well burnt or slightly over burnt.• If the struck against the same type of brick

they use to emit ringing sound.• They are rectangular in shape and have well

defined edges but not in equal size mm2.

Second Class Bricks

59

• They have clean surface but with certain small irregularities

• They are free from major cracks but have slight flaws and chips

• Even if it soaked for 24hours it will absorb less than 22% of water.

• They have the minimum crushing strength of 7 N/mm2.

60

• The second class bricks are used in masonry constructions, where faces are to be plastered, is used for the construction of load bearing walls of single storey houses, used as brick ballast in R.C.C work and in lime concentrate.

Uses of Second Class Bricks

61


Second class bricks

• These bricks are under burnt and have some cracks and rough surface.

• They are light colored and are relatively soft.• When they stuck with the same type of brick it

emits dull sound. • They are not in uniform sizes and slightly

distorted. • They do not have well defined sharp edges and

corners.

Third Class Bricks

63

• They are not in uniform sizes and slightly distorted. • They do not have well defined sharp edges and

corners. • They may show intensive sign of efflorescence • In the fractured surface of the bricks they don’t have

the proper uniform textures, it may show pebbles. • These bricks will have the water absorptions of 20 %

to 25 %. They have the minimum compressive strength of 3.5 N/mm2.

64

• This third class bricks are used in the construction of unimportant structures; they are used in the constructions of low height structures, where the loads are much less, such as construction of huts, sheds, etc; used in the construction of boundary walls; used in the areas where it is not exposed to rain.

Third class bricks uses

65

• As their name shows, these are over burnt since remained near fire in Kiln so get fused and loose their shape.

• These may have bulging surfaces.• They have very light or very dark color like

black/grey.• Their compressive strength is very low and

can not be used for civil structures.

Over burnt Bricks

68

• These are used for inferior construction works like aggregate, road metal, water bound and gravels for floor works.

Over burnt bricks uses

69

• Preparation of Brick Earth– Un-soiling– Digging– Weathering– Blending– Tempering

• Molding of Bricks• Drying of Bricks• Burning of Bricks

71

Manufacturing of Bricks

Excavation of soil

Carting of Water from Source for mixing in the soil

Mixing of sand in the soil

Mixing of clay with Feet to form clay paste

Preparation of Bricks by inserting lump of clay paste in the mould

Placing the newly moulded bricks on the ground for drying

Tools and equipments require for brick making

Transportation of fully dried bricks for placing in the kiln

Arranging the bricks in the Kiln for firing

Fully prepared Kiln ready for firing

Un-soiling – Removal of top 20 cm organic matter and free from gravel, coarse sand, lime etc.

Digging –soil excavated, additives spread, puddle, watered and left over for weathering.

Weathering – heaps left for one month for oxidation and washing away of excessive salts in rain.

Blending – sandy earth and calcareous earth mixed in right proportions with right amount of water.

Tempering – kneading of blended soil with feet or with a pug mill to improve plasticity and homogeneity.

82

Preparation of Brick Earth


Blending brick clay

84

Pug Mill

Molding – giving right shape ◦ Hand molding

Ground molding. Molded on sand. No frog in bricks

Table molding. Molded on stock boards with frog

◦ Machine molding Plastic method or Stiff-Mud process. Molded stiff clay bar cut by wire into

brick size pieces.

Dry Press method. Moist powdered clay fed into machine to be molded into bricks.

Drying Natural drying: also known as hack drying, bricks are dried in open air and

sunlight.

Artificial drying: brick are dried in Kiln chamber or tunnel.

85

Manufacturing of Burnt Bricks


Hand molding of bricks

87

Brick Molds

88

Table Molding

89

Strikes


Extruded – Wire Cut Extruded – Smooth

Wood MoldExtruded – Raked

91

Method of Drying Bricks


Drying of bricks


Protecting dry bricks

• Burning Stages– Dehydration (400-650 °C). Water smoking stage in which

water from pores is driven off

– Oxidation (650-900 °C). Carbon eliminated and ferrous iron oxidized to ferric form. Sulphur is removed

– Vitrification (900-1250 °C). Mass converted into glass like substance

95


Clamp or Pazawah Burning◦ Alternate layers of bricks and fuel encased in mud plaster.◦ Fuel consists of grass, cow dung, wood, coal dust◦ Brick layer consists of four to five courses of brick◦ 25,000 to 100,000 bricks in three months cycle

Kiln Burning◦ Intermittent kiln. Loaded, fired, cooled and unloaded

before next loading◦ Continuous kiln. Bricks are loaded, fired, dried and cooled

simultaneously in different chambers. Example: Bull’s trench kiln and Hoffman’s kiln

96


97

Clamp Burning


Burning of bricks in kilns


Burning fuel

100

Hoffman’s Continuous

Kiln

Loading raw bricks

Removing cooled bricksCooling bricks

Fuel supply

Preheating

Cool air entering

Hot air leaving

101

Bull’s Trench

Kiln

Loading raw bricks

Unloading cooled bricks

Cooling bricks

Preheating bricks

Size and shape – uniform size, rectangular surfaces, parallel sides, sharp straight edges

Color – uniform deep red or cherryTexture and compactness – uniform texture,

fractured surface should not show fissures, holes, grits or lumps of lime

Hardness and soundness – not scratch able by finger nail. Produce metallic ringing sound

Water absorption – should not exceed 20% wtCrushing strength – not less than 10.5 N/mm2

Brick earth – free from stones, organic matter

102

Characteristics of Good Bricks

• Heavy duty bricks• Perforated bricks• Paving bricks• Hollow bricks• Clay tiles• Fire-clay or refractory bricks

103

Miscellaneous Brick Types

These Bricks are made from fire-clay, using same process as an ordinary clay.

The color of the Brick is yellow or light brown.The water absorption varies from 4-10 %.The compressive strength b/w 150-200

N/mm2

Used for the lining blast furnaces, Ovens, Kiln, Boilers and Cimneys.

104

Fire clay (refractory bricks)

105

Refractory bricks

106

Specially Shaped Bricks

Compressive strength Test. Specimen brick is immersed in water for 24 hoursThe frog of brick is filled flush with 1:3 mortar and

brick is stored under damp jute bags for 24 hours followed by immersion in clean water for three days.

The specimen is then placed between plates of compression testing machine.

Load is applied axially at uniform rate till failure. Maximum load at failure divided by average area of bed face gives compressive strength.

107

Testing of Bricks

Absorption Test.◦ 24 hours immersion cold water test.

Dry bricks are oven dried at 105° ± 5° C Room temperature cooled bricks weighed W1 Bricks immersed in water at 27° ± 2° C for 24 hrs Soaked bricks weighed W2 Water absorption in % = (W2 – W1)/W1 x 100

◦ Five hours boiling water test Oven dried bricks weight : W1 Bricks immersed in water and boiled for 5 hours and then

cooled down at room temperature in 16-19 hours Cooled down weight as W2 Water absorption in % = (W2 – W1)/W1 x 100

108

Testing of Bricks

Efflorescence Test. The soluble salts if present in bricks cause efflorescence on the surface of brick.

Brick is immersed in water for 24h. It is then taken out and allowed to dry in shade. The absence of grey or white deposits on its surface indicates absence of soluble salts.◦ Nil imperceptible efflorescence◦ Slight deposit covers area < 10% of exposed area◦ Moderate deposit covers exposed area 10% to 50%◦ Heavy deposit covers exposed area > 50%◦ Serious deposits are heavy and powder or flake away

the surface

109

Testing of Bricks

Structure Test. A specimen is broken and its structure is examined.

It should be homogeneous, compact, and free from defects e.g., lumps and holes, etc.

Soundness test. This test is performed by striking two specimen bricks with each other. The bricks should not break and a clear ringing sound should be produced.

Hardness test. This test is performed by making a scratch on brick surface with the help of finger nail. If no impression is left on surface, the brick is considered to be sufficiently hard.

110

Testing of Bricks

Over-burning. Burnt beyond complete vitrification

Under-burning. Burnt less not to cause complete vitrification

Bloating. Spongy swollen mass over the surface due to excess carbonaceous matter and sulphur

Black Core. Due to bituminous matter or carbon

111

Defects of Bricks

112

Efflorescence. Grey of white crystallization of alkalis on the surface, due to water absorption

Spots. Dark sulphur spots due to iron sulphidesBlisters. Broken blisters due to air entrapped during

moldingLaminations. Thin lamina produced due to air

entrapped in voids of clay

• Concrete Hollow Block (CHB) is a hollow masonry unit, with two or three cells or cores, made of the following ingredients: water, Portland cement, and various types of aggregate such as sand, gravel, and crushed stone.

• Lightweight concrete hollow blocks are also manufactured with such aggregates as cinders, expanded slag, expanded shale or clay. Expanded blast furnace slag rates the highest in fire resistance, and due to its cellular structure, has high sound and thermal insulation quality.

• These are manufactured by machine-mixing the ingredients, pouring the mix into molds, and curing the block by air drying. A steam-and-pressure curing process is also used which can produce concrete hollow block in a few hours.

CONCRETE HOLLOW BLOCK

• Standard CHB sizes are from thicknesses of 100mm (4”), 150mm (6”) and 200mm (8”) x height of 200mm (8”) x length of 400mm (16”).

• CHB of 100mm (4”) thickness should be used only for interior partition walls where weather-tightness is not required.


• The different types of concrete hollow block include:


a. Stretchers

b. Headers

c. Corner blocks

d. Jamb blocks

e. Beam or lintel blocks

• Concrete hollow blocks should be laid on a full bed of mortar with horizontal and vertical joints 10mm (3/8”) thick.

• Reinforcement for 100mm (4”) and 150mm (6”) thick wall shall be 10mm vertical bars at 600mm on centers and 10mm horizontal bars every third course.


• Reinforcement for 200mm (8”) thick walls shall be 12mm vertical bars at 600mm on center and 12mm horizontal bars every third course.

• All horizontal reinforcement shall be tied to the vertical reinforcement at their intersections.

• Dowel bars should be placed into the piers, columns, slabs, leaving 20 bar diameters exposed to splice with the reinforcement of the hollow blocks.

• Block cells with reinforcement are filled with cement mortar.

• Concrete hollow block walls should have a reinforced concrete lintel or beam block course every twelfth course; and a concrete column stiffener at every 4.80 meters length.


- “DURISOL” block is lightweight block made from fiber and cement.

- “DURISOL” block units are two-core, 100mm (4”) or 150mm ( 6”) x 87mm (7-1/2”) x 600mm (24”).

- Reinforcement shall be 10mm vertical bars at 720mm (36”) on center and at every 4th course. Every 4th course should be a beam block course. Cores shall be solidly filled with cement mortar.

“DURISOL” BLOCK

PLASTER BLOCK

- also known as gypsum partition blocks, are usually made of gypsum, vegetable fibers as binders, and reinforcement.

- used for lightweight, fire-resistant interior partitions and for furring and fireproofing columns.

- Gypsum hollow blocks are manufactured in units of 75mm (3”), 100mm (4”) or 150mm ( 6”) thicknesses, x 300mm (12”) height x 700mm (30”) length.

- Gypsum solid block is manufactured only with a 50mm (2”) thickness.

STRUCTURAL CLAY TILE

- Structural clay tile are hollow masonry units, open at two ends with interior webs or partitions 19mm (¾”) to 25mm (1”) dividing the block into longitudinal cells.

- In its manufacture, the various shapes of clay tile are formed through special dies and then wire-cut into the required lengths.

- It may have a smooth or scored (grooved) surface. Structural clay tile is classified into:

a. Load-bearing wall tile. 300mm x 300mm x 300mm (12” x 12” x 12”)

b. Non-load bearing, fireproofing, partition, and furring tile. 100mm (4”) or 125mm (5”) x 200mm x 300mm