Bricks

BRICKS MASONRY

INTRODUCTION TO HISTORICAL INTRODUCTION TO HISTORICAL DEVELOPMENTS IN MASONRYDEVELOPMENTS IN MASONRY

• It is the simplest of all the building techniques - Mason stacks It is the simplest of all the building techniques - Mason stacks pieces of material (bricks, stones, concrete blocks, etc.) over the pieces of material (bricks, stones, concrete blocks, etc.) over the top of one another to make walls, with mud or mortar as binding top of one another to make walls, with mud or mortar as binding material in between themmaterial in between themHistoryHistory

• Began as low walls of stones or caked mudBegan as low walls of stones or caked mud• Sun-dried bricks - With the availability of fire became burnt bricksSun-dried bricks - With the availability of fire became burnt bricks• Invention of kilns made mass production of bricks easyInvention of kilns made mass production of bricks easy• Limestone turned into lime mortar replaced mud as mortarLimestone turned into lime mortar replaced mud as mortar• In Mesopotamia, palaces and temples were built of stone and sun-In Mesopotamia, palaces and temples were built of stone and sun-

dried bricks in 4000 B.C.dried bricks in 4000 B.C.• The Egyptians erected their temples and pyramids of stones by The Egyptians erected their temples and pyramids of stones by

3000 B.C.3000 B.C.• By 300 B.C., Greeks perfected their temples of limestone and By 300 B.C., Greeks perfected their temples of limestone and

marblemarble• Romans made the first large-scale use of masonry arches and roof Romans made the first large-scale use of masonry arches and roof

vaults in their basilica, baths and aqueductsvaults in their basilica, baths and aqueducts

INTRODUCTION TO HISTORICAL INTRODUCTION TO HISTORICAL DEVELOPMENTS IN MASONRYDEVELOPMENTS IN MASONRY (Cont’d)(Cont’d)

• Medieval and Islamic civilizations perfected masonry vaulting Medieval and Islamic civilizations perfected masonry vaulting to a high degree of development - Islamic craftsmen built to a high degree of development - Islamic craftsmen built palaces, markets, and mosques of bricks and often faced palaces, markets, and mosques of bricks and often faced them with brightly glazed tilesthem with brightly glazed tiles

• Europeans built fortresses and cathedrals using pointed vaults Europeans built fortresses and cathedrals using pointed vaults and flying buttressesand flying buttresses

• In America and Asia other cultures were building with stonesIn America and Asia other cultures were building with stones• During industrial revolution, machines were developed to During industrial revolution, machines were developed to

quarry and cut stones, mould bricks, and speed the quarry and cut stones, mould bricks, and speed the transportation of these materials to site of buildingtransportation of these materials to site of building

• Portland cement came into wide use and this enabled the Portland cement came into wide use and this enabled the construction of masonry building of greater strength and construction of masonry building of greater strength and durabilitydurability

• Late in 19th century tall buildings were built, of steel and Late in 19th century tall buildings were built, of steel and reinforced concrete (pored into simple forms), economically reinforced concrete (pored into simple forms), economically

• Development of hollow concrete forms in 19th century Development of hollow concrete forms in 19th century averted the extinction of masonry as a building material - averted the extinction of masonry as a building material - Cavity wall, developed by the British during the earlier part of Cavity wall, developed by the British during the earlier part of the 19th century also contributed to the survival of masonry the 19th century also contributed to the survival of masonry as a building materialas a building material

• This facilitated the introduction of thermal insulationThis facilitated the introduction of thermal insulation• High strength mortars, high-strength masonry units, and High strength mortars, high-strength masonry units, and

complex shapes of masonry units extended the use of complex shapes of masonry units extended the use of masonry for buildingsmasonry for buildings

INTRODUCTION TO HISTORICAL INTRODUCTION TO HISTORICAL DEVELOPMENTS IN MASONRYDEVELOPMENTS IN MASONRY (Cont’d)(Cont’d)

Masonry - Primary Uses TodayMasonry - Primary Uses Today Concrete Masonry Units (CMU)Concrete Masonry Units (CMU) Foundation WallsFoundation Walls Structural Support Walls (low rise)Structural Support Walls (low rise) Backup Walls for Exterior FacingBackup Walls for Exterior Facing Brick & StoneBrick & Stone Facing Materials - VeneersFacing Materials - Veneers Decorative WallsDecorative Walls

CMU Structural Walls on a Low Rise Building

Reinforcing Structural CMU Walls

• Bricks will categorized with different used: – load bearing wall– Non-Load bearing wall– Insulation wall– Covering wall.

• Selection of bricks based on their using.• Brick shape : 4 side geometric with length 2 x from

width. The thickness is 2/3 of width• Standard size of bricks is 215 x 102.5 x 65 mm• It’s can be made from clay, sand & lime, cement

mortar

Brick will not burn, buckle or melt. Brick will not rot and allow Termites to invade. Brick will not rust and corrode. Brick will not dent. Brick will not fade from the Sun's UV (ultra-violet) Rays. Brick will not be damaged by high winds, rain or hail. Brick will not require constant maintenance. Brick will not devalue. Brick will not limit your personal expression. Brick will not limit your design options. 

Clay Bricks• Manufactured from clay. The basic

compositions of clay brick are:

i. Silica (Si O2) – 60%ii. Alumina (Al2 O2) – 20%iii. Remaining ingredients – 20%

• Remaining ingredients such as: i. Calcium oxideii. Iron oxide – give pleasing red colouriii. Manganeseiv. Magnesium oxide

Functions of Ingredients• Silica – Free silica (sand), if added to clay in

suitable proportion makes a brick hard and prevents it from warping and shrinking on drying.

• Alumina – Alumina is main constituent of every clay. On the addition of water clay becomes plastic and can be moulded into shape.

• Lime – It helps to lower the fusion temperature, i.e. it helps silica to fuse at lower temperature and thus helps to bind the particle together. It also prevents shrinkage of raw bricks

Harmful ingredients• Alkalise – The alkalise lower the fusion

temperature and melts the brick, changes it shape or get twisted. Also these salts have hygroscopic action.

• Iron pyrites – during burning, iron pyrites due to high temperature oxidise, decompose and disintegrate brick into pieces.

• Organic matter – Although the presence of organic matter in brick helps it burning, this causes porosity in the bricks. The presence of organic matter such as roots, dry leaves, in brick should be avoided.

Characteristics of good bricks

1. Appearance and colour –  A good brick should have a uniform rectangular shape with even surfaces and sharp corners. It should be free from cracks. It should have a uniform brick-red colour.

2. Hardness and soundness – Good bricks should be hard and should not be scratched by fingernail. Also, should give a metallic sound when two brick are struck to each other.

3. Durability – A good brick should be able to withstand weathering actions of Sun, rain wind etc.

4. Fire resistance – A good brick should be able to withstand a temperature up to 1500˚ F or 816˚ C.

5. Strength – A good brick is strong enough to not to break, when dropped on another brick from a height of about 1.25 Meters.

• Engineering bricks :-

6. Water absorption – A good brick should not absorb more than 20% of water by weight, when placed in water for 24 hours.

7. Efflorescence – It should not contain much alkaline salts which causes efflorescence on the surface and decays the brick.

Min. Compressive Strength

Max. water absorption

Class A 70 N/mm2 4.5%

Class B 50 N/mm2 7.0%

Types of clay bricks• Common type or common bricks

– These are ordinary bricks, which are not designed to provide good finishes appearance or high strength

• Facing bricks– These are designed to give attractive appearance;

hence they are free from imperfections such as cracks

• Engineering bricks– These are designed primarily for strength and

durability. They are usually of high density and well fired.

• Facing bricks are used primarily in the construction of external walls in domestic and commercial applications.

• They are chosen for their aesthetic appeal and technical characteristics, including their speed of use in construction.

• They must also meet minimum standards for weather resistance.

• Facing bricks are made using either soft mud or extruded techniques.

• Soft mud bricks are generally more expensive to produce than extruded bricks.

• Soft mud bricks are made by throwing clay into a mould.

• This throwing process is generally automated, but some soft mud bricks are hand-made

• Engineering bricks are designed for use where the strength of the brick or the need for a brick to have a low level of water absorption is paramount (eg in the construction of retaining walls or for ground works.

• Engineering bricks are usually extruded bricks. The majority of engineering bricks sold are smooth red Class B bricks, which are also among the cheapest bricks sold. Class A engineering bricks have lower water absorption than Class B engineering bricks and are more expensive to buy.

• They are often blue-grey in appearance, and are generally used in facing applications on account of their distinctive appearance.

• In most, but not all, facing applications, Class B engineering bricks are considered to be less attractive than facing bricks, and their colour may be less uniform.

Different between facing bricks & engineering bricks

Manufacture - 4 stages◦ Material preparation◦ Moulding◦ drying◦ Firing

Material Preparation: material (clay) washed and

grinding (fineness)

Sample of grinding machine for clay

Sample of crushing machine

Materials / Clay preparation• Clay is prepared by crushing and/or

grinding and mixing with small quantities of sand, ash and lime until it is of a uniform consistency.

• Water may be added to increase plasticity (a process known as ‘tempering’). In some cases chemicals such as barium carbonate is added to reduce the problem of efflorescence, crystallisation damage or chemical attack of the mortar.

Materials preparation Weathering • The soil is left in heaps and exposed to weather for at

least one month in cases where such weathering is considered necessary for soil.

• The soil is turned at least twice and it is ensured that the entire soil is wet throughout the period of weathering.

• The purpose of weathering is to disintegrate big boulders of clay under the action of atmospheric agencies to make it a uniform mass and also to eliminate the impurities which get oxidized.

Materials preparation (Cont’d)Tempering • After weathering, the required quantity of water

should be mixed with the soil to obtain the right consistency for moulding. Addition of sand and other materials, if necessary, may be made at this stage to modify the composition of the soil.

• The quantity of water to be added, may range from ¼ to 1/3 of the weight of soil, sandy soils requiring less water and clayey soils more water. But the nature and degree of wetness of the soil at this stage should also be duly considered.

• There are 4 methods of moulding;

– Semi-dry process

– Stiff plastic process

– Wire-cut process

– Soft mud process

• Used in manufacture of bricks having a moisture content of around 10% in the clay

• The ground and the screened material has a dry granular consistency which is still evident in the fractured surfaces of the fired brick

• Applicable to clays having a moisture content of about 15%

• Should possess stiff plasticity

• Clay is extruded and then compacted into a mould under higher pressure

• Many engineering blocks are made by this process

• Clay is tempered to 20% moisture content

• Extruded to a size which allows for drying and firing shrinkage

• Units are cut to the correct thickness by tensioned wires

• For clays having very high moisture content

• Clay is pressed into moulds having sanded surfaces to prevent the clay from sticking to the surfaces of the mould

After bricks become in form, then the identification or perforation will occur to the bricks.

Drying : Wet unit bricks will be drying

in space or room with control temperature to make sure that the bricks completely dry.

Brick compile before taking to the kiln

Drying• Drying is essentially evaporation of moisture either in

a normal atmosphere or with controlled humidity and temperature.

• Drying is done prior to burning of bricks. The purpose is to reduce the tendency of the bricks to distort or crack while burning.

• Drying is slow, otherwise cracks may develop on its surface. The process is usually take a number of days (3 to 10 days).

• For artificial drying, this is done by drying bricks in chambers or tunnels.

• Hot flue gases may be used to heat these chambers or tunnels. Temperature is usually maintained at 120C and the bricks get dried within 1 to 3 days.

Firing : Dry bricks, compile in kiln to

start the firing process with 600oC (temperature). This is for burn the carbon and sulfur that have remain.

After that, temperature will increase to 900oC to get a verification process.

Normally, verification process occurred around 800oC.

Bricks become hard/strong after verification process.

Beehive Kiln

Tunnel Kiln

30Bricks manufacturing process flow

MATERIAL PREPARATION

Manufacturing

Manufacturing

Setting

Firing Process

Packaging

Quiz

• Why it is important that, the bricks meet certain absorption requirements?

• Explain a method to measure the water absorption on bricks.

• Explain the term of ‘tempering’ in clay bricks preparation.

There are many types of brick. Some are different in formation and composition while others vary according to their use

brick is made of ordinary clays or shale and burned in the usual manner in the kilns. These bricks do not have special scorings or markings and are not produced in any special color or surface texture. Common brick is also known as hard- and kiln-run brick. It is used generally for backing courses in solid or cavity brick walls. The harder and more durable kinds are preferred for this purpose.

bricks are used in the exposed face of a wall and are higher quality units than backup brick. They have better durability and appearance. The most common colors of face brick are various shades of brown, red, gray, yellow, and white.

bricks that have been over burned in the kilns. This type of brick is usually hard and durable and may be irregular in shape. Rough hard corresponds to the clinker classification.

made by the dry press process. This class of brick has regular smooth faces, sharp edges, and perfectly square corners. Ordinarily, all press brick are used as face brick.

bricks have one surface of each

brick glazed in white or other colors. The ceramic glazing consists of mineral ingredients that fuse together in a glass-like coating during burning. This type of brick is particularly suited for walls or partitions in hospitals, dairies, laboratories, or other buildings where cleanliness and ease of cleaning are necessary.

is made of a special type

of fire clay that will withstand the high temperatures of fireplaces, boilers, and similar usages without cracking or decomposing. Firebrick is larger than regular structural brick, and often, it is hand molded.

Are made with two rows of five holes extending through their beds to reduce weight. There is no significant difference between

• stretcher brick is a brick laid with the longest side exposed

• header brick is a brick laid with the smallest end exposed to the weather

• soldier is a brick laid on its end vertically

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Header - Bonds two wythes together Wythe: vertical layer 1 unit thick

Soldier - Laid on its end, face parallel

Rowlock - laid on face, end visible

Stretcher - long dimension horizontal & face parallel to the wall

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Basic Brickwork TerminologyBasic Brickwork Terminology

BedJoint

HeadJoint

Course - horizontal layer of brick

• Entirely comprised of stretcher bricks, set in rows that are offset by half a brick.

• Most common bond in modern time • Can consist of one layer , two layers or

two layers with a gap in between • The main advantage of this technique

is that it allows walls with both faces visible, and can be used for : domestic low-height walls where the part of the structure above is built of a lighter,framed material such as glass to be built using low-cost bricks that have only two fair faces

is made up of alternating courses of stretchers and headers. This produces a solid wall that is a full brick in depth. English bond is fairly easy to lay and is the strongest bond for a one-brick-thick wall. If only one face of an English bond wall is exposed, one quarter of the bricks are not visible, and hence may be of low visual quality.

(also known as Spanish bond) was

a very common bond for bearing walls. It is composed of header bricks, set in rows that are offset half a brick, which produces a solid easy to lay bond which is useful when building circular work. It is the most used bond in historical Spanish brick constructions. Picture shows Header bond.

Flemish bond, also known as Dutch bond, has historically always been considered the most decorative bond, and for this reason was used extensively for dwellings until the adoption of the cavity wall. It is created by alternately laying headers and stretchers in a single course. The next course is laid so that a header lies in the middle of the stretcher in the course below. Again, this bond is one brick thick. It is quite difficult to lay Flemish bond properly, since for best effect all the perpendiculars (vertical mortar joints) need to be vertically aligned. If only one face of a Flemish bond wall is exposed, one third of the bricks are not visible, and hence may be of low visual quality. This is a better ratio than for English bond, Flemish bond's main rival for load-bearing walls.

A common variation often found in early 18th century buildings is Glazed-headed Flemish Bond, in which the exposed headers are burned until they vitrify with a black glassy surface. Monk bond is a variant of Flemish bond, with two stretchers between the headers in each row, and the headers centered over the join between the two stretchers in the row below.

Flemish bond photoFlemish bond photo

• These bonds are variations on normal bonds. They use a high proportion of stretchers, and hence require fewer facing bricks than normal bonds. This makes them less sturdy, but cheaper to lay. As such they are most commonly used for garden- and other non-load-bearing walls.

• Flemish garden wall bond has a header alternating with (typically) three stretchers in each course. Flemish garden wall bond was commonly used for garden walls in southern England.

• English garden wall bond has a course of headers alternating with (typically) three courses of stretchers. English garden wall bond was typically used in northern England for buildings where English bond would have been used in southern England, and not just for garden walls.

• Scottish bond has one row of headers to five of stretchers.• American common bond is made by laying the courses of headers where they are

separated by approximately five to seven courses of stretchers. On occasion American common bond can be found with nine courses of stretchers between courses of headers. The stretcher courses are most often an uneven number.

Rat-trap bond, also known as Chinese bond, is a type of garden wall bond in which the stretchers and headers are laid on their sides, with the base of the stretcher facing outwards. This gives a wall with an internal cavity bridged by the headers, hence the name. The main advantage of this bond is economy in use of bricks, giving a wall of one brick thickness with fewer bricks than a solid bond. Rat-trap bond was in common usage in England for building houses of fewer than 3 stories up to the turn of the 20th century and is today still used in India as an economical bond, as well for the insulation properties offered by the air cavity. Also, many brick walls surrounding kitchen gardens were designed with cavities so hot air could circulate in the winter, warming fruit trees or other produce spread against the walls, causing them to bloom earlier and forcing early fruit production.

• When bricks are laid on alternating angles, it is called a Herringbone. This is primarily a decorative style, more often used for paving or fireplace reflectors than for walls. It is generally considered unsuitable for load-bearing structures, but may be found as infill in traditional timber framed buildings. This style is also sometimes called by its Latin name: Opus spicatum.

• This decorative pattern imitates the weave of a basket. It is also sometimes called basket weave bond, and there are many variations on the weave pattern, some very elaborate.

Decorative of brick work

Walk way

MORTAR

• A cushion and makes the masonry units to A cushion and makes the masonry units to bear against one another and thus provides bear against one another and thus provides strength to the wallstrength to the wall

• A seal in between the masonry units, and A seal in between the masonry units, and keeps the water and air from penetrating itkeeps the water and air from penetrating it

• A bonding agent to make the individual units A bonding agent to make the individual units to adhere to one anotherto adhere to one another

• A surface enhancer , proving beautiful A surface enhancer , proving beautiful contrast and appearancecontrast and appearance

MORTAR (Cont’d)

• Mortar is made of Portland cement, hydrated Mortar is made of Portland cement, hydrated lime, and aggregates (sand) and water. lime, and aggregates (sand) and water. Portland cement acts as bonding agent, lime Portland cement acts as bonding agent, lime imparts smoothness and workability, sand imparts smoothness and workability, sand provides the bulk around which lime sets, and provides the bulk around which lime sets, and water provides workability to set bricks water provides workability to set bricks properly. Setting of hydrated lime with properly. Setting of hydrated lime with absorption of COabsorption of CO2 2 from air makes the mortar from air makes the mortar strongstrong

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Mortar FunctionsMortar Functions

Provides for full bearingProvides for full bearing Seals between masonry unitsSeals between masonry units Adheres / bonds masonry unitsAdheres / bonds masonry units AestheticsAesthetics

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Brickwork StrengthBrickwork Strength Depends on:Depends on:

– Strength of the masonry unitStrength of the masonry unit– Strength of the mortar Strength of the mortar

References

• http://www.glengerybrick.com/about/manufacturing/index.html

• http://brickcollecting.com/history.htm• http://www.oldvirginiabrick.com/technical/

bond_patterns.html• http://www.ixlbrick.com/index.php?

page=bond-patterns

Compressive strength test• The specimen brick is immersed in water for 24

hours. The frog of the brick is filled flush with 1:3 mortar and the 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 the plates of the compression testing machine. Load is applied axially at a uniform rate of 14N/mm2 (140 kgf/cm2) and the maximum load at which the specimen fails is noted for determination of compressive strength of brick given byCompressive strength = max load at failure / loaded area of brick