Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
Source: www.wikipedia.org 2
M A S O N R Y
• Masonry is the assembly of “building blocks” bonded together with mortar to form walls and other parts of buildings
• Building blocks can be brick, stone, concrete block, glass block, adobe, terra-cotta, etc…
3
H I S T O R Y O F M A S O N R Y C O N S T R U C T I O N
• Bricks has been used in constructions since 9000 years ago in the ancient Mesopotamia and Palestine
• Ziggurat of Ur in Iraq (mud-clay brick)
Source: http://www.chaplainfisher.com4
H I S T O R Y O F M A S O N R Y C O N S T R U C T I O N
• Roman (70 BC - 476 AD) used masonry extensively. They invented the arch construction which allows them to build large openings. They also discovered natural cement (pozzolana).
Roman Colloseum (70-80 AD)
Source: www.wikipedia.org 5
H I S T O R Y O F M A S O N R Y C O N S T R U C T I O N
• Masonry has been used extensively in the constructions throughout the middle ages and renaissance period.
Leaning Tower of Pisa (1173-1372)
Source: www.wikipedia.org 6
H I S T O R Y O F M A S O N R Y C O N S T R U C T I O N
• Brick masonry are used in tall buildings up until about 1900s
Monadnock Building in Chicago (completed 1891)The tallest masonry building at 60 m (17 stories)The brick walls bear the weight of the building. The walls are over 2 m. thick at their base.
Source: www.answers.com 7
H I S T O R Y O F M A S O N R Y C O N S T R U C T I O N
Monadnock Building (1891)Load-Bearing Masonry
Reliance Building (1891)Steel Frame
Comparison of masonry building and steel building of the same period
8
H I S T O R Y O F M A S O N R Y C O N S T R U C T I O N
• Today, brick walls constructions are usually limited to:– Low-rise building (1-2 story)– Curtain walls (non load-bearing wall)– Veneered walls, mostly for architectural
Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
Source: www.wikipedia.org 10
B U I L D I N G B L O C K S
• Many materials may be used as “building blocks” in masonry construction such as:– Stone– Adobe Brick– Kiln-Burned Brick– Concrete Brick/ Block– Glass Block– Terra-Cotta– Etc…
Stone Masonry11
B U I L D I N G B L O C K / A D O B E
• Adobe brick (Sun-dried brick)– The most primitive type– Made from sun-dried clay and
often reinforced with hay– Usually found in semi-dessert
areas due to its good insulating properties
– Walls are very thick (about 40 cm) and typically limited to one story
12
B U I L D I N G B L O C K / B R I C K
• Kiln-burned brick– Most widely used type of brick– Made from clay, shale, fireclay,
or the combination of these materials, fired in the kiln for hardness
– Surface Clay – is found on the surface of the earth from sedimentation
– Shale – is clay which has been subjected to high pressure until they become hard. They must be ground before it can be used to make brick
– Fireclay – found at deeper levels. It usually has more uniform physical and chemical qualities and has the ability to withstand high temperature
13
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
• The manufacturing of brick consists of 6 main steps
• Mining of raw material• Preparing of raw material• Forming of units• Predrying• Burning and Cooling• Packing and shipping
14
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G1) Mining of raw materials
3) Forming units 4) Predrying for burning
5) Burning and Cooling 6) Packing and Shipping
2) Preparing raw materials
15
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
• Raw material is dug out of the ground
16
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
Preparation of materials before forming17
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
• Forming of Units: there are 3 methods– Soft-Mud Process: This involved mixing clay with water into a relatively soft
mud (about 25-30% water content) and formed in a mold. Due to the high water content, the brick has very high drying shrinkage. It is impossible to precisely control the size and shape of the brick.
– Stiff-Mud Process (extrusion process): Clay with lower water content (about 12-15%) is extrude though a rectangular die. It is then cut by wires to the size. In this process, it is easy to put holes in the brick by placing a hole-shaped blockages in the die face. The brick in this method shrinks less during drying than the soft mud process due to its lower water content.
– Dry-Press Method: Clay with low water content (less than 10%) is compressed into steel molds by means of high pressure (3-10 MPa). Due to its low water content, the brick shrinks very little and it is possible to produce bricks with very accurate dimensions.
18
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G• The choice of process depends on the moisture of the clay and the
tolerance on the shape and size of brick.– Soft-Mud Process
– Stiff-Mud Process(Extrusion Process)
– Dry-Press Process
Mold
Clay
DryBricks to be burned
Clay
Extruder
Cutter
Bricks to be burned
Wet Clay
Dry Clay
Poorly-Shaped Brick
Well-formed Brick
Mold
Clay
DryBricks to be burned
19
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
Extruder and wire cutter (stiff-mud process)
Drying of cut brick
20
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
In this factory, the dried brick is reshaped again using pressure (i.e. dry-press process) and let dry a little bit more before burning
21
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
• Predrying (step 4) is to remove moisture out of the brick before burning– Temperature ranges from 38-204 °C– Time ranges from 24-48 hours– During the drying, brick may shrink between 2-6% from the formed size (in step
3). This shrinkage must be allowed for by making the wet brick slightly larger.– Humidity must be controlled to avoid rapid shrinkage
• Burning (step 5) is to make brick stronger and water-resistant– Several heating steps may occur in the kiln – Temperature ranges from 149-1315 °C– Time ranges from 40-150 hours– The brick may shrink further, around 2-6% depending on the clay
• Cooling (step 6) must be done carefully to avoid shrinkage crack– Control rate of cooling– Time ranges from 48-72 hours
22
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
Kiln
Heat
Exhaust
Kiln is constructed with firebrick
Fuel
• Capacity: 30000 bricks (9” x 4” x 3”)
• 900-1000 Celcius inside
• Takes 6 days to complete the burning processes
• Leave the brick to cool down for 3-4 days
23
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
• Modern brick factory uses tunnel kiln in which bricks are dried, fired, and cooled in a continuous process.
Source: Illston and Domone (2001) 24
B U I L D I N G B L O C K / B R I C K / M A N U F A C T U R I N G
Bricks ready to be shipped
25
B U I L D I N G B L O C K / B R I C K / P R O P E R T I E S
• Properties of brick vary widely due to: – different material used at each location– manufacturing process (repressing – make a denser brick, burning method)– quality control
• A good brick should be: – reasonably uniform in texture and shape, – free from defects (cracks, chipped edges, warpage, embedded foreign materials)– not soft from underburning
26
T E X T U R E & C O L O R
• Texture is a result of the manufacturing process used
• Color of the brick depends on its chemical composition and manufacturing process/ treatments– Clays consist of Silica and Alumina with some metallic oxides and other
minerals• Calcareous clays – have 15% CaCo3 Yellow brick• Noncalcareous clays – have feldspar and 2-10% iron oxide Red brick
– Burning temperature affects the brick color• Higher temperature Darker brick (also higher in compressive strength)
• If the brick is to be exposed, it is advisable to buy enough brick for the job at one time to ensure uniform color throughout
27
C O L O R
Yellow Brick
Red Brick
28
T Y P E S, S H A P E S, & S I Z E S
• Types of brick by shapes– Solid– Perforated– Frogged– Cellular– Hollow
• Types of brick by usage– Building Brick (common brick)– Face brick– Paving brick– Special brick
Source: Hendry and Khalaf (2001)29
T Y P E S, S H A P E S, & S I Z E S
Source: Hendry and Khalaf (2001)30
T Y P E S, S H A P E S, & S I Z E S
31
T Y P E S, S H A P E S, & S I Z E S
• Why do we need holes in the brick:– Usually brick does not carry much loads (just the weight of itself) so it does not
have to be very strong– Even if it is load-bearing, we need larger brick for stability rather than for strength– Save weight easier to lift, save the transportation cost– Save material good for environment, cheaper– Easier to dry and burn– Improved thermal insulation
32
S T A N D A R D S F O R B R I C K S
• มอก. 77-2545 อฐิกอ่สรา้งสามัญ• ASTM C62-97 Standard Specification for Building Brick (Solid Masonry
S T A N D A R D S F O R C O N C R E T E B L O C Kคอนกรตีบล็อครับนํ้าหนัก
Source: มอก 57 (2533) 42
S T A N D A R D S F O R C O N C R E T E B L O C K
Source: มอก 57 (2533) 43
S T A N D A R D S F O R C O N C R E T E B L O C K
Source: มอก 58 (2533) 44
B U I L D I N G B L O C K S / C O N C R E T E B L O C K
45
B U I L D I N G B L O C K S / C O N C R E T E B R I C K
Lightweight Concrete Brick– They are made from portland
cement, sand, and lime (CaO or Ca(OH)2) with some additives that reacts with lime to creates air bubbles inside the concrete. The bubble may comprise up to 75% of the total volume of the block
– Available sizes: 20×60 cm, 30×60 cm
– Typically 7.5-25 cm thickness– Using glue to hold the bricks, not
mortar
46
L I G H T W E I G H T C O N C R E T E B R I C K S
Lightweight Concrete Brick• Advantages:
– Reduced Weight of structure– Good Insulation & Fire Protection
due to the air voids– Faster to construct– Can be cut easily with a special
knife
• Disadvantages:– Expensive– Durability when exposed– Water Permeability?– Security?
Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
48
C O M P R E S S I V E S T R E N G T H
• Typical Range: 10-140 MPa• ASTM C 62 specifies minimum
compressive strength requirements:
• Test Procedure– Test ½ brick flatwise under
compressive load– The brick must be dried and
its surfaced coated with shellac to prevent moisture absorption, which can reduce the measured strength
– The bearing surface must be capped with capping material to provide smooth surface
ASTM Grade มอก. ชัน้คณุภาพ
Min compressive strength (avg. of 5
bricks)
Severe Weather
ก 21 MPa
Moderate Weather
ข 17 MPa
Normal Weather (Interior)
ค 10 MPa
c
Pf' =
A
Compressive Strength is calculated as:
49
F L E X U R A L S T R E N G T H
• Also called Modulus of Rupture• Some correlation between flexural strength and compressive strength• Typical Range: 1.5-20 MPa• Test Procedure:
– Apply point load at the midspan (through a steel bearing strip) of a simply-supported brick
– Modulus of Rupture is calculated as:
• Brick in masonry structure may be subjected to bending force due to incomplete mortar bedding
M cMOR =
I
50
A B S O R P T I O N
• Used as a measure of brick porosity, which can be related to:– Possible leakage through brick– Durability of brick, especially when subjected to freezing and thawing
cycles– Strength of brick (the denser of the brick, the stronger it is)– The ability of mortar/plaster to attach to the brick surface - the brick
may absorb too much water from mortar which could lead to shrinkage in mortar and lower bond between brick and mortar
• Differences in material and manufacturing processes make it impossible to compare absorption of bricks from two plants and relate that to the strength and other properties
• Most bricks must be soaked in water before laying to reduce absorption
51
A B S O R P T I O N• Test Procedure
– Obtain oven-dry weight by drying brick at 110-115 °C until it has a constant weight
– Obtain wet weight by immerse the brick in water at 15-30 °C for 24 hours. Then weight the brick.
– Absorption is calculated as:
• Typical Range: 1-25% (a good brick should have absorption < 20%)• ASTM C 62 specifies minimum compressive strength requirements for brick:
wet dry
dry
W -WAbsorption = ×100%
W
ASTM Grade มอก. ชัน้คณุภาพ Max Water Absorption (avg. of 5 bricks)
Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
53
M O R T A R
• Mortar is generally defined as the mixture of:– Portland cement – provides the strength– Sand – acts as a filler and provides durability and strength– Lime (optional) – provides workability– Water – react (hydration) with portland cement
54
M O R T A R
• Desired properties of mortar for masonry:– The consistency has to be thick enough that it hangs on the trowel but not too
thick that it is difficult to spread– It must not lose water easily and stiffen when contact with absorptive brick– It must remain in plastic state long enough to allow for laying and adjusting of
brick line– It must develop a good bond to brick– It must be durable and provide watertight joint
• Good mortar does not necessarily have high strength!– High strength mortar tends to develop few large cracks (allowing easy
penetration of water) while weaker mortar tend to develop several small hair cracks (which is also less noticeable).
– Typically, the strength of masonry should be less than or equal to that of the brick.
55
M O R T A R T Y P E S
• Lime Mortar (Lime + Sand + Water)– Good workability but develop strength very slowly
• Cement Mortar (Portland Cement + Sand + Water)– Gives a dense and strong mortar, which may be too strong– Good for location with high stress or foundation where watertightness is
+ Mineral Filler)– Mineral Filler and Air-Entraining admixture increase workability– May include retarder admixture– Composition and property vary with the manufacturer
56
P R O P O R T I O N I N G O F M O R T A R
Cement-Lime Mortar• The higher the lime, the lower the
Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
58
B R I C K M A S O N R Y W A L L S
• Brick masonry walls can be categorized into 2 groups: load-bearing and non load-bearing walls– Load-Bearing Walls: The masonry wall
carries the weight of the entire building (floors, roof, etc…). The walls are usually thick, often build with two or more rows of brick walls (called wythes). Example: Old castles, Roman buildings, Monadnock building.
Load bearing wall at the ground floor of Monadnock building
59
B R I C K M A S O N R Y W A L L S
– Non Load-Bearing Walls: The masonry wall does not carry any loads. The loads of floors are carried by either reinforced concrete or steel frame. The masonry wall is just for partitioning the space or for decorative purposes.
The span length between columns is just too large to be a masonry construction. Actually, this building has reinforced concrete frame. The brick walls are just decorative façades.
60
B R I C K M A S O N R Y W A L L S
Load-Bearing Walls can be further categorized into several types:
• Solid Walls– 2 or more “wythes” – They can be bonded together
by using brick headers or metal ties
• Cavity Walls/ Rowlock Wall– Create an air space between
two wythes for improved insulation or to prevent passage of moisture from outer wall
– Not permitted in areas with high probability of earthquakes
Source: Smith and Andres (1989) 61
B R I C K M A S O N R Y W A L L S
• Reinforced Walls– Have steel reinforcement grid
in grout space between two wythes to provides better bond
– For areas subjected to earthquakes or tornados/ hurricane
• Faced Wall– Brick wall in the front tied with
other backup wall (such as concrete block or cast-in-place concrete wall)
– Brick is structurally tied to the backup wall
Source: Smith and Andres (1989) 62
B R I C K M A S O N R Y W A L L S• Reinforced Walls
Source: Hendry and Khalaf (2001) 63
B R I C K M A S O N R Y W A L L S
Non Load-Bearing Walls can be further categorized into several types:
• Veneered Wall– Brick wall in the front not
structurally tied with the wall behind (such as wood)
• Curtain Wall– Brick is used as filler in RC or
steel frames– It has to be able to carry its own
weight and horizontal wind load– Need to have some means to
transfer horizontal load to the structural frame Source: Smith and Andres (1989)
64
B R I C K M A S O N R Y
– Brick masonry structure must be in compression through the use of arches, domes, and vaults
65
B R I C K M A S O N R Y
Forces Along the Arch
Reaction ForcesReaction Forces
Vertical Loads
Construction of arch
Force transfer in arch
66
B R I C K M A S O N R Y
Ponte de Tiberio (27 BC to 14 AD) Rimini, Italy
Pont du Gard (Roman Aqueduct) (circa 19 BC) Nimes, France
Source: www.wikipedia.org
Source: www.wikipedia.org67
B R I C K W O R K S
• The pattern in which the bricks stack together is called “bond”
• There are several patterns possible, some for strength purposes, some for architectural purposes.
Source: Hendry and Khalaf (2001)68
B R I C K W O R K S
69
B R I C K W O R K S
Source: Hendry and Khalaf (2001) 70
B R I C K W O R K SEnglish Bond
Common Bond
71
B R I C K W O R K SFlemish Bond
Running Bond
72
B R I C K W O R K S
• Decorative brickworks
73
B R I C K W O R K S
• Patterns for stone masonry walls
Source: Hendry and Khalaf (2001) 74
M O R T A R J O I N T S
• The appropriate thickness of mortar joint is about 1 cm• Mortar joint is selected to create a special effect on brick wall (for
architectural purposes), or to shed water
Recommendedfor Exterior Walls
75
A D V A N T A G E S O F B R I C K M A S O N R Y
• Advantages– Brick is relatively cheap and
requires minimal technology to make one
– Good insulation property– Fire resistant– Usually does not require
sophisticate equipments to construct
– Does not need to be painted (reduce cost)
• Disadvantages– Structure is massive & heavy
• Need large foundation• Floor space lost to walls• Cannot have large openings• Susceptible to earthquake
– Stability and weight of the structure limits the height
– Need a very skilled masons for arches, roofs, vaults
– Slow construction (compared with steel and wood)
– Structure must be in compression the entire time – therefore, it has poor seismic-resisting capacity
Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
77
F A C T O R S A F F E C T I N G M A S O N R Y B E H A V I O R
• The strength and durability of the overall masonry structure depends on:– Quality of the brick (strength and uniformity of shapes)– Quality of the mortar (strength and bond property)– Relative behavior of brick and mortar– Workmanship– Pattern the units are laid
• The strength of the masonry unit is less than that of the brick or mortar because failure tend to occur at the weakest point which could be:– A brick that has unusually low strength– Improperly bonded brick-mortar joints– A location of stress concentration
• As a result, the strength of the brick rarely controls the behavior of the brick masonry
78
F A C T O R S A F F E C T I N G M A S O N R Y B E H A V I O R
• The followings can be observed:
• Masonry strength increases linearly with the brick strength
• The greater the mortar strength, the greater the masonry strength
• Masonry strength is less than the brick strength
Source: Illston and Domone (2001)
79
C O M P R E S S I V E S T R E N G T H
• Masonry is very good in resisting compression• Compressive strength of masonry normal to the bedding plane is greater
than the compressive strength parallel to the bedding plane.
Compression Parallel to bedding plane
Compression Normal to bedding plane
80
C O M P R E S S I V E S T R E N G T H
• Overlapping of bricks helps distribute the compressive load normal to the bedding plane
• Brick has poor compressive strength parallel to bedding plane because there is no overlapping
Source: Illston and Domone (2001)
81
S T A B I L I T Y
• Compressive load-carrying capacity of the masonry wall decreases when the slenderness ratio (height / thickness) of the wall increases because wall may be in bending due to some minor eccentricity of the loading and may fail in tension.
• The decrease in Stability with height is what limits the height of masonry structure. Tall masonry structures needs a large base and heavy walls to be stable, which at some point becomes uneconomical.
Source: Illston and Domone (2001) 82
S T A B I L I T Y
>
• The wall on the right becomes unstable easier than the left.
83
B E N D I N G S T R E N G T H
• Bending strength when loaded in normal direction is greater than when loaded in the parallel direction
Parallel Direction
Normal Direction
84
D U R A B I L I T Y O F M A S O N R Y
• Masonry structure is relatively durable. However, under certain conditions, the masonry may be deteriorated over time:– Salt crystallization: This occurs when dissolved salts are carried into pores in
the brick through groundwater or atmospheric pollutants. When the weather is warm, the water evaporates and the salts start to crystallize in the pores below the surface. The crystal form has larger volume than the solution so it create pressure inside the pore. Eventually, the surface of the brick flakes off.
– Sulfate attack: Sulfate attacks the mortar in the same way as sulfate attack in concrete.
85
D U R A B I L I T Y O F M A S O N R Y
– Acid attack: acid attacks the mortar in the same way as sulfate attack in concrete. Acids may be from atmospheric pollution (sulfur, nitrogen, or carbon acids) or from organics (algae, mosses, bacteria, plants) grown on the surface of the brick.
86
D U R A B I L I T Y O F M A S O N R Y
– Efflorescence: This occurs due to water (from rain) dissolve the soluble salts within the brick. The solution crystallize on the surface as white powder and may be washed out by rain later. In some cases, the Ca(OH)2 in the mortar was leached out and reacts with CO2 to form Ca(CO)3 on the surface.
87
C R A C K I N G I N M A S O N R Y B U I L D I N G S
• Crack in masonry walls occurs as a result of deformation/ movement beyond the limit that can be accommodated by the materials (which is not very much!)
• Common causes of cracking:– Thermal expansion – Shrinkage of the block (occurs in concrete block construction)– Soil movement/settlement (occurs in masonry walls set directly on soil
foundation)– Deflection of structural frame (occurs in curtain/infill masonry walls built inside
a reinforced concrete or steel frame)
• The cracking patterns are different for each case - experiences are needed to be able to diagnose the cause of the cracks.
88
C R A C K I N G I N M A S O N R Y B U I L D I N G S
Source: Hendry and Khalaf (2001)
89
C R A C K I N G I N M A S O N R Y B U I L D I N G S
Source: Hendry and Khalaf (2001)90
C R A C K I N G I N M A S O N R Y B U I L D I N G S
Source: Hendry and Khalaf (2001)
91
C R A C K I N G I N M A S O N R Y B U I L D I N G S
Source: Hendry and Khalaf (2001)
92
C R A C K I N G I N M A S O N R Y B U I L D I N G S
• Prevention of these crackings must be done during the design and construction stages– Cracking due to thermal expansion can
be prevented by incorporate a “movement joint” into the design
– Shrinkage can be avoided by proper selection of materials
– Soil movement can be reduced by proper design and construction of the foundation
– Cracking due to structural frame deflection can be avoid by not attaching the wall to the structural frame, or incorporate a movement joint. Or if the structure is expected to deform a lot, then masonry may not be a suitable material for such application.
Introduction• Definition• History of Masonry Construction
Concrete Block• Manufacturing
Processes• Types, Shape
& Sizes• Strength & Physical
Properties
94
R E F E R E N C E S
• Brantley, L. R. and Brantley, R. T. (1996), Building Materials Technology: Structural Performance & Environmental Impact, McGraw-Hill, New York, 327 pp.
• Hendry, A. W. and Khalaf, F. M. (2001), Masonry Wall Construction, Spon Press, London.
• Kreh, R. T. Sr. (1982), Masonry Skills, Delmar Publishers, New York, 328 pp.• Microsoft Corporation (1999), Encarta Encyclopedia, Richmond, WA.
• Rosen, H. J. and Heineman, T. (1996), Architectural Materials for Construction, McGraw-Hill, New York, 319 pp.
• Smith, R. C., Andres, C. K. (1989), Materials for Construction, 4th Edition, McGraw-Hill, New York, 401 pp.
• Watson, D. A. (1986), Construction Materials and Processes, 3rd Edition, McGraw-Hill, New York, 486 pp.
