5. MATERIAL - WEEK 5

BRICK MASONRY

Brick Masonry

9.1 BRICK MASONRY - OVERVIEW      

9.2 INTRODUCTION TO HISTORICAL DEVELOPMENTS IN MASONRY 9.3 USES AND TYPES OF MASONRY MORTAR 9.4 MANUFACTURE OF BRICKS FROM CLAY 9.5 SIZES, GRADES AND TYPES OF BRICKS 9.6 TERMINOLOGY, BONDS AND JOINTS IN BRICK MASONRY 9.7 TYPES OF BRICK MASONRY WALLS AND STRUCTURES

9.2 INTRODUCTION TO HISTORICAL DEVELOPMENTS IN MASONRY  It is the simplest of all the building techniques - Mason stacks pieces of material (bricks, stones, concrete blocks, etc.) over the top of one another to make walls, with mud or mortar as binding material in between them

 9.2.1 History     

Began as low walls of stones or caked mud Sun-dried bricks - With the availability of fire became burnt bricks Invention of kilns made mass production of bricks easy Limestone turned into lime mortar replaced mud as mortar In Mesopotamia, palaces and temples were built of stone and sun-dried bricks in 4000 B.C.  The Egyptians erected their temples and pyramids of stones by 3000 B.C.  By 300 B.C., Greeks perfected their temples of limestone and marble  Romans made the first large-scale use of masonry arches and roof vaults in their basilica, baths and aqueducts

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

 Medieval and Islamic civilizations perfected masonry vaulting to a high degree of development - Islamic craftsmen built palaces, markets, and mosques of bricks and often faced them with brightly glazed tiles  Europeans built fortresses and cathedrals using pointed vaults and flying buttresses  In America and Asia other cultures were building with stones  During industrial revolution, machines were developed to quarry and cut stones, mould bricks, and speed the transportation of these materials to site of building  Portland cement came into wide use and this enabled the construction of masonry building of greater strength and durability

9.2 INTRODUCTION TO HISTORICAL DEVELOPMENTS IN MASONRY (Cont’d)  Late in 19th century tall buildings were built, of steel and reinforced concrete (pored into simple forms), economically  Development of hollow concrete forms in 19th century averted the extinction of masonry as a building material - Cavity wall, developed by the British during the earlier part of the 19th century also contributed to the survival of masonry as a building material  This facilitated the introduction of thermal insulation  High strength mortars, high-strength masonry units, and complex shapes of masonry units extended the use of masonry for buildings

Masonry History  Rich History  Through the mid-1800s – Primary Building Materials

 Late 1800s – New Products Developed – Ended Masonry’s Dominance

Masonry History  20th Century Developments – Steel Reinforced Masonry – High Strength Mortars – High Strength Masonry Units – Variety of Sizes, Colors, Textures & Coatings

Masonry - Primary Uses Today  Concrete Masonry Units (CMU) Foundation Walls Structural Support Walls (low rise) Backup Walls for Exterior Facing  Brick & Stone Facing Materials - Veneers Decorative Walls – Load bearing wall

Brick Masonry - Uniqueness  Fire Resistance  Size  Durability

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CMU Structural Walls on a Low Rise Building

Reinforcing Structural CMU Walls

CMU Structural Walls also serving as a “Backup” Wall for Brick

9.3 USES AND TYPES OF MASONRY MORTAR 

9.3.1 Uses and Types of Masonry Mortar

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Mortar is as much a part of masonry as masonry units such as bricks, stones, etc.

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Mortar serves as : (1) A cushion and makes the masonry units to bear against

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one another and thus provides strength to the wall; (2) A seal in between the masonry units, and keeps the water and air from penetrating it; (3) A bonding agent to make the individual units to adhere to one another; and (4) A surface enhancer , proving beautiful contrast and appearance Most characteristics type of masonry mortar is made of Portland cement, hydrated lime, and aggregates (sand) and water. Portland cement acts as bonding agent, lime imparts smoothness and workability, sand provides the bulk around which lime sets, and water provides workability to set bricks properly. Setting of hydrated lime with absorption of CO2 from air makes the mortar strong Masonry mortar (has various trade names): Contains one or more of the following, viz. , Portland cement, Portland-pozzolan cement, natural cement, slag cement, Portland-blast furnace slag cement, hydraulic lime, and in addition usually contains hydrated lime, limestone, chalk, calcareous shell, talc, slag and/or clay

Mortar Functions  Provides for full bearing  Seals between masonry units  Adheres / bonds masonry units  Aesthetics

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Joint Color that “Blends” w/ Brick Color 18

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Mortar  Pre-packaged  Color range  Testing / Specifications  Curing  “Shelf” life

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9.3 USES AND TYPES OF MASONRY MORTAR (Cont’d) 

In order to achieve workability, masonry mortars contain air-entraining admixtures that produce high air content in mortar; this reduces the bond strength of masonry mortar - For these reasons, for masonry work that requires high strength and low permeability, only conventional cement-lime mortar should be used - Lime mortar cures by drying and absorption of CO2 from air to form CaCO3, whereas Portland cement mortar cures by hydration that produces a dense, strong, and crystalline structure that binds the sand particles together - To prevent premature drying masonry units should be wetted before laying them in course.

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Mortar types : (a) M-type - High strength mortar - 2,500 psi - Used for buildings subjected to large lateral loads, and below grade (earth level) masonry; (b) S-type - Medium high strength mortar - 1600 psi - Used for masonry structures needing high flexural bond strength and normal compressive loads: (c ) N-type - Medium strength mortar - 750 psi - for general use above grade; and (d) O-type - Medium low strength mortar; 350 psi - Used for non-load-bearing walls and partition

9.4 MANUFACTURE OF BRICKS FROM CLAY 

Bricks have greater fire resistance than stone or concrete masonry - Its size enables easy handling and placement in walls; it can be easily adapted to small-scale and large-scale structures to give pleasing appearance and texture

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Constituents: Brick clays are produced by blending together various clays (surface clays, shales, and fire clays) to produce the desired chemical composition and physical properties - Clays can be divided into calcareous clays (containing 15% Calcium Carbonate, which gives yellow color when burnt) or noncalcareous clays (containing silicate of alumina, feldspar, and iron oxide) - Iron oxide gives buff, red or salmon color, when burnt

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Molding of Brick: The raw material is dug from pits, crushed, ground, and screened to reduce it to a fine constituency - Then it is tempered with water to produce a plastic clay for forming into brick

9.4 MANUFACTURE OF BRICKS FROM CLAY (Cont’d) 

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Methods of forming : Three different processes are used for brick forming (i) Soft Mud Process: A relatively moist clay (containing 20% to 30% of water) is pressed into molds, either by hand or machine - The mold may be dipped in water (water-struck bricks) or dusted with fine sand (sand-struck bricks) before filling it with clay - (ii) Dry press bricks are formed with clays that shrink excessively during drying - Is mixed with minimum amount of water(10%) - (iii) Stiff mud Process: Most widely used process nowadays - contains 12 % to 15% of water - passed through vacuum to remove any pocket of air, and then extruded through a rectangular die to form bricks The rectangular column of moist clay extruded through the die is cut by automatic wire cutters to form individual bricks - After molding and cutting, the bricks are dried for one or two days in low-temperature kilns - Then they are ready for firing or burning

9.4 MANUFACTURE OF BRICKS FROM CLAY (Cont’d) 

Firing of Bricks: Bricks are burnt either in a periodic kiln or a continuous tunnel kiln - In a periodic kiln bricks are loaded in after initial drying, fired, cooled, and unloaded; and the process is repeated after a certain period (say a month) - In a continuous tunnel kiln the bricks are loaded onto special railcars that pass continuously through various processes to emerge at the other end fully burned

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Stages of burning: Water-smoking and dehydration (drives off the remaining water from clay at 40o to 150o C) - Oxidation and Vitrification: Temperature of furnace rises to 1000o to 1300o C - Clay transformed to a ceramic material Flashing: Fire is regulated to create a reducing atmosphere in the kiln that develops a color variation in the bricks - Cooling: Bricks are cooled under controlled conditions to achieve the desired color and to avoid any thermal cracking - The entire process of firing takes from 40 to 150 hours

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Color of a brick: Depends on the chemical composition of clay, temperature, and chemistry of fire - Iron in clay turns to red in oxidizing fire and to purple in reducing fire - Calcium oxides gives creamy/white color - For bright colors, all faces of bricks can be glazed like pottery during normal firing or during subsequent firing

Brick Masonry - Sizes and Shapes  No standard size  Normal coursing - 4 bricks = 300-310mm  Larger sizes  Custom Shapes & Colors

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9.5 SIZES, GRADES AND TYPES OF BRICKS (Cont’d)  Grades of Building Bricks - Grade SW: Withstands severe weathering (freeze-thaw, alternate wetting and drying) - Grade MW: for moderate weathering - Grade NW: for negligible weathering

 9.6.3 Types of Facing Bricks - Type FBX: High degree of mechanical perfection, narrow color variation, minimum size variation per unit - Type FBS: Wide range of colors, greater variation of size per unit - Type FBA: Nonuniformity in size, color and texture.

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Extruded – Wire Cut

Wood Mold

Extruded – Smooth

Extruded 30 – Raked

Brickwork Strength  Depends on: – Strength of the masonry unit – Strength of the mortar

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9.6 TERMINOLOGY, BONDS AND JOINTS IN BRICK MASONRY  9.6.1 Terminology used in laying bricks: Bed joint, Head joint, Collar joint, Wythe, Stretcher, Header, Soldier, Rowlock

 9.6.2 Structural bonds used during brick laying  Running Bond: All courses of brick made of stretchers, with breaking of joints, from one course to the other

 English Bond: made of alternate courses of stretchers and headers, with breaking of joints

 Common Bond or American Bond : Made of stretchers courses, with every sixth course being made completely of headers, with breaking of joints

 Flemish Bond: In the same layer ( or course) stretchers and headers are laid alternatively, with breaking of joints

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Basic Brickwork Terminology Head Joint Bed Joint

Course - horizontal layer of brick

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

Rowlock laid on face, end visible

Stretcher - long dimension horizontal & face parallel to the wall

Soldier - Laid on its end, face parallel

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Brick Bonds  Structural Bonds  Cavity (Veneer) Walls – Running bond – Stacked bond

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9.6 TERMINOLOGY, BONDS AND JOINTS IN BRICK MASONRY(Cont’d)  Procedure for building brick walls: (i) Laying of lead (or corner bricks) to establish the wall planes and courses heights - (ii) Bricks in between leads are laid to a line ( a heavy string stretchers taut between line blocks at each lead)

 9.6.3 Joint Tooling:      

Required for giving beauty to mortar joints Weathered Joint: Mortar joint has sloped (downwards) edge Concave joint: Joint concave inwards Vee joint: mortar joint is in the form of a V Flush Joint: Mortar joint is flush with the brick surfaces Raked Joint: A large portion of the mortar joint is raked out - Not a safe, impermeable joint  Struck Joint: Mortar joint has a sloped (upwards) edge  Mortar joints can vary from 1/4” to 1/2” - Usually taken as 3/8”

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Laying Masonry  Layout & Leads  Line

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Stationary Scaffolding 39

Masonry Joints Weathered Concave

 Size

Vee

 Joint Tooling

Flush

 Joint Profiles

Racked Concave Struck

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Concave Joints 41

Raked Joints

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9.7 TYPES OF BRICK MASONRY WALLS AND STRUCTURES 

9.7.1 Spanning Openings in Brick Walls

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Brick walls must be supported above openings for windows or doors, using

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reinforced concrete lintels, reinforced brick,or steel angles A corbel is an ancient structural device of limited spanning capability, that may be used for small openings in brick walls, for beam brackets, and for ornamental provisions.

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Arches can be used instead of lintels to span large openings in walls- Different forms of arches can be built: Segmental Arch, Jack Arch, Tudor Arch, Elliptical Arch, Roman Arch (cylindrical shape), Goethic Arch, Parabolic - Arch Terminologies: Intados, Extrados, Soffit, Spring line, Skewback, Crown, Span, Rise

Steel Lintel

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Simulated Precast Concrete Lintel (actually a steel lintel supports the assembly)

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Arch

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