CEEN 3144 Construction Materials
Masonry
Francisco Aguíñiga
Assistant Professor
Civil Engineering Program
Texas A&M University – Kingsville
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Masonry construction
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Masonry construction today
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Masonry evolution
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Masonry materials
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Clay brick and tile
Concrete Masonry Units (CMU)
Adobe
Mortar
Grout
Steel reinforcement
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Clay Brick and Tile
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Raw material
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Hydrated silicate of alumina
Manufacture of fired clay
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Stiff mud
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Soft mud
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Wire cut process (12 to 15% water by weight)
Forced through a die (20 to 30% water by weight)
Press process
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Grind, add 7 to 10% water by weight, press (500 to
1500 psi)
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Brick types
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Building brick
Facing brick
Hollow brick
Structural clay load-bearing wall tile
Structural clay facing tile
Ceramic glazed facing tile
Paving brick
Sound-absorbing clay masonry
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Building brick (ASTM C62)
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Most common brick
Physical properties
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Color
Texture
Form and dimension
Engineering properties
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Durability
Initial rate of absorption
Compressive strength
Stiffness
Flexural strength
Thermal conductivity and expansion
Acoustical characteristics
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Physical
properties
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Physical
properties
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Durability
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Severe weathering (SW)
Moderate weathering (MW)
No weathering (NW)
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Durability
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Grade requirements for different
exposures
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Water absorption
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Absorption is a measure of the ability of
a brick to form a good bond with mortar
ASTM C67 - absorption % of brick
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Immerse sample for 24 hr in cold water
Record cold water absorbed as % of dry weight of
the unit
Immerse same sample in boiling water for 5 hr
Record hot water absorbed as % of dry weight of
the unit
Calculate cold water/boiling water ratio (C/B),
known as saturation coefficient
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Water absorption
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C/B represents the portion of the total
pore space readily filled with water
C/B < 80% - Good freezing protection
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Initial rate of absorption
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Pores or small openings function
as capillaries - draw water into the
unit
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Called rate of absorption – suction
Important effect on tensile bond between
brick and mortar
ASTM C67
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Initial rate of absorption
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Some effects of high initial rate of
absorption
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Difficult to lay brick, water removed too rapidly
from mortar bed – loss of workability
Brick layer tends to tap brick as he shoves it into
place – disruption of bond between brick and
mortar
Water drawn from mortar by brick so fast that
there is not enough water left for proper curing
Very high suction leads to walls that are not
watertight
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Tensile bond strength
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Compressive strength
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Obtained as described in ASTM C67
Compressive strength can be affected
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Other important factors include
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Physical properties of the clay
Method of manufacture
Degree of burnig
Compressive strength of mortar, grout, and prism
assemblage
Compressive strength of a composite
prism (brick + mortar + grout) is less
that those of the clay unit itself
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Stiffness
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Modulus of elasticity (between 1.4
and 5 Msi) increases with
compressive strength up to about
5000 psi
The modulus of a composite prism
(Brick + grout + mortar) is less
that that of the clay unit itself
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Facing brick
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ASTM C216
Durability
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Stringent aesthetic requirements
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Only SW and MW exist
Color, texture, and form
Compressive strength
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Similar to ordinary brick (2500 psi min for
MW and 300 psi min for SW)
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Hollow brick
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Similar shape to concrete blocks
About 25% of the volume are voids
Features
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Very high compressive strength
Face shell is thick enough to provide stability and
sound mortar beds
Requirements for cross beds are similar to
concrete block
Cell sizes and areas allow for reinforcement and
insulating fill placement
Provides valid fire ratings either hollow or grouted
ASTM C652 – two grades SW, and MW
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Hollow brick
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Hollow brick
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Structural clay load-bearing wall
tile
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Structural clay load-bearing wall
tile - ASTM C34
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Paving brick
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Used in steps, sidewalks,
platforms, accessible areas
ASTM C62 or ASTM C216
Grades – only SW
Color – Generally terra cotta red
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Paving brick
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Wall patterns
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Wall patterns
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Mortar joints
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Concrete Masonry Units
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Ingredients
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Portland cement ASTM C150
Hydrated lime ASTM C207 Type S
Poozonals ASTM C618
Other constituents
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Air entraining, coloring, water repellents
Aggregates (normal weight ASTM C33, and lightweight
ASTM C331)
ASTM designations
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Hollow and solid load-bearing capacity ASTM C90
Concrete building brick ASTM C55
Non load-bearing concrete masonry units ASTM
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C129
Concrete Masonry Units
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Moisture requirements
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Concrete M.
Units
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Block dimensions
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Minimum thickness of webs
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Strength and absorption
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Joint types
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Mortar
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Purpose of mortar
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Fill irregularities between masonry units
Provide resistance to penetration of light, wind,
and water
Bond the units together
Perhaps add strength
Early mortars – mud, bitumen or tar
New mortar – lime
Mortar requirements by modern codes
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Provide well-bonded and weather resistant wall
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Mortar
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Ingredients
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Cement
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Portland cement (UBC Standard 26-1 or ASTM
C150)
Masonry cement (UBC Standard 24-16)
Mortar cement (UBC Standard 24-19)
Water – clean, free of alkali (mixing and
curing)
Lime
Sand
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Lime
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Calcium oxide (CaO)
Hydrated calcium oxide Ca(OH)2
Serves mainly as a plasticizing agent –
cement provides the basic strength
Increases water retentivity - reduces
bleeding and segregation
Fabrication
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Limestone is pulverized, blended, and heated to
2500°F
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Sand
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Properties of sand significantly influence the
workability and strength of mortar
Grading requirements ASTM C144 and UBC
Standard 24-21
Fine sand is preferable over coarse sand
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Admixtures
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Generally neither necessary nor
recommended
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Water reduction
Water retention
Water proofing
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Mix proportions
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