Masonry Flashcards

1
Q

Mortar

A

mixture of cement, lime, sand, and water

  • normally portland cement is used
  • lime is a plasticizer; helps retain water improving workability

Made of portland cement, hydrated lime, an inert aggregate (sand), and water
• Sand must be clean and screened to get out particles that are too coarse or fine
• Portland cement is “harsh” meaning that it doesn’t flow well on a trowel or under a
brick….lime is added to impart smoothness and workability
• Lime is made by burning limestone or seashells in a kiln to drive of CO2 and leave
quicklime, which is then allowed to absorb as much water as it will hold. This is
called hydrated lime. It’s dried, ground, and bagged for shipping

Makes up about 20% of the exposed surface of a brick wall

• Serves to cushion the masonry units and allow them to bear fully against one another
despite surface irregularity
• Seals between the units to keep water and wind from penetrating
• Adheres units to one another to bond them into a monolithic structural unit
• Portland cement mortar cures by hydration, not by drying. A set of chemical reactions
take up water and combine it with the cement and lime to create a dense, strong
crystalline structure that binds sand particles and masonry units together
• If mortar is mixed less than 90 minutes prior to its stiffening it has only dried and a
mason can safely retemper it with water to make it workable again (note, this is not
the case with concrete!)
• Mortar older than 2 1/2 hours must be discarded because it has begun to hydrate and
can’t be retempered without reducing its final strength

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2
Q

masonry cement

A

prepared mixture of portalnd cement and pulverized limestone

  • not as strong of expensive as portland cement, but has greater plasticity
  • suitable for lowrise building veneers and for interior, non loadbearing applications
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3
Q

mortar types

A

Types M or S: for masonry that is load-bearing and/or exposed to the weather.
• Types N and O: lesser compressive strength required.

  • each has a different porportion of cement, lime, and aggregate
  • each has a different compressive strength
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4
Q

grout

A

similar to mortar

  • used to fill cavities between masonry units
  • fine grout is used when dimensions of cavity is less than 2 in
  • course grout includes no 4 aggregate
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5
Q

• Grades for Building and Facing Bricks

A

• Grade SW: Sever Weathering (Oregon, most of the Eastern half of US)

  • Grade MW: Moderate weathering (Midwest, most of Washington)
  • Grade NW: Negligible weathering (Along southern US border)

• ASTM testing procedures establish three grades of brick based on resistance to weathering and three types of facing bricks, bricks that will be exposed to view, based on the degree of uniformity in shape, dimension, texture, and color from one brick to the next

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6
Q

brick masonry

A

Produced by factories all over the place with local clay and shale. It’s expensive to
ship long distances because it’s so heavy.

  • After molding bricks are dried for 1-2 day sin a low temp dryer kiln and then fired
  • Entire process of firing takes about 40 - 150 hours
  • There’s no truly standard brick size. The most common is 8” x 3 5/8” x 2 1/4”
  • Use of larger bricks can lead to substantial economies in construction
  • Brick shapes can be solid, cored, hollow, or frogged
  • Reducing the volume of a brick reduces fabrication, transportation costs
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7
Q

molding method for brick

A
  • Molding methods:
  • Soft mud process: (oldest method) relatively moist clay is pressed into simple rectangular molds
  • Dry-press process: use for clays that shrink excessively during drying, clay mixed with water is pressed into steel molds by a machine working at high pressure

• Stiff mud process: high-production, most widely used, clay with water is extruded and sliced by wires to form brick

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8
Q

Types of Facing Bricks

A

available in SW and MW grades

• Type FBX: High degree of perfection, narrow color range, slight size variation

  • Type FBS: Wide range of color and greater size variation per unit
  • Type FBA: Non uniformity in size, color, and texture per unit
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9
Q

• Needle Beam:

A

a temporary member thrust under a building or foundation used in underpinning

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10
Q

Hallow brick

A

available in SW and MW grades

-classified according to appearance

HBS: general use where range of size and color variation are acceptable or desired

HBX: used when a high degree of mechanical perfections, narrow color range, and minimum variation in size is required

HBA: non uniform in color, size, and texture

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11
Q

Wythe:

A

simplest wall, a vertical layer of masonry units one unit thick

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12
Q

Course:

A

a horizontal layer of bricks or other masonry units

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13
Q

Stretcher:

A

a brick laid with its face parallel to the wall and its long dimensions
horizontal

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14
Q

Header:

A

a brick laid to bond two wythes together

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15
Q

Solider:

A

brick laid on its end with its face (long skinny side) parallel to the wall

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16
Q

Sailor:

A

brick laid on its side with its end parallel to the wall

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17
Q

Rowlock:

A

brick laid on its face with its end (short skinny side) visible in the wall.
Often used for caps on walls and floor sloping sills under windows

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18
Q

Name Brick laying positions

A
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19
Q

name common mortar joints

A
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20
Q

Expansion joints are required when structure is over

A

200’ long or where wings occur

  • Major expansion joints are spaced every 100 ft to 150 ft in large buildings
  • expansion and control joitns are spaced every 20 ft and at places where the wall changes direction, height, or thickness
  • horizontal expansion joints should be placed below shelf angles that support intermediate sections of brick and below beams and slabs above brick
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21
Q

Joints in brickwork are tooled ___hours after laying as the mortar begins to harden,

A

1-2

-joints must be appropriate for the weather condition the wall is located in.

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22
Q

the slope of brick coping at top of a masonry wall is called

A

the wash

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23
Q

Efflorescence

A

• Sometimes appears on the surface of a wall of brick, stone, or concrete masonry
• Consist of one or more water soluble salts that were originally present in the
masonry unit or in the mortar
• Brought to the surface and deposited there by water that seeped into the masonry,
dissolved the salts, then migrated to the surface and evaporated
• Can be avoided by choosing masonry units that are lab tested and don’t contain
water soluble salts
• Will eventually diminish and disappear with time as the salt is gradually leached
out of the wall

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24
Q

Abutment/Construction/Isolation Joints:

A

placed at junctions between masonry
and other materials, or between old and new masonry, to accommodate
differences in movement.

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25
Q

tuck pointing or repointing

A
  • method of restoring mortar in masonry walls
  • mortar in areas to be redone is removed to about 2.5 times the depth of the joint
  • joint is then cleaned and wetted with water
  • new mortar is pressed into the joint with a special tuck pointing tool
  • high lime mortar is best and should be applied in layers
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26
Q

Concrete Masonry Units (CMU’s)

A

• Stiff concrete mixture is placed in steel molds, cured, and quickly dried. • Includes concrete brick, concrete block, concrete tile, and cast stones

• Typical concrete block size is 7 5/8” x 7 5/8” x 15 5/8”
• Many colors and surfaces types are available
• Hollow concrete block masonry is generally more economical per unit of wall area
than brick or stone masonry.
• Blocks are cheaper on a per unit basis and made into a wall more quickly
because of their size
• Widely used in masonry bearing wall construction due to strength and insertion of
rebar and grout into cores
• Often used as a backup wythe behind brick or stone facing, or stucco, plaster, tile
• Single wythe exterior concrete masonry walls tend to leak in wind driven rains
• Exterior should be painted with masonry paint
• Walls subject to moderate stresses can be reinforced horizontally with steel joint
referencing which is thin enough to fit into an ordinary bed joint of mortar
• Vertical reinforcing is done with ordinary reinforcing bars grouted into the cores
of the blocks
• Lintels for concrete block are comparable to those of brick masonry:
• Steel lintel: wide flanged section welded to a plate
• Reinforced block lintel: made of bond beam units filled with grout and rebar • Precast reinforced concrete block lintel: totally visible
• Decorative CMUs
• Easily made in a variety of surface patterns, textures, colors, interior/exterior
applications
• Include scored face, ribbed face, fluted face, angular face, etc.

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27
Q

concrete blocks are considered solid when

A

it has 75% or more solid material in any general cross section, otherwise it is considered hallow

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28
Q

CMU dimension are based on…

A

nominal 4 in module

  • actual dimensions being 3/8 in less than the nominal dimension
  • unit dimension are referrede to by width, height, and then length
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29
Q

What is the equivalent thickness of an 8 in thick concrete block that is 60 % solids

A
  • equivalent thickness is the solid thickness that would be obtained if the same amount of concrete contained in a hallow unit were recast without core holes
  • actual thickness = 7 5/8 in (7.625 in)

equivalent thickness then = (7.625)(.60)=

4.58 in

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30
Q

Structural Clay Tile:

A

hollow burned clay masonry units, architectural terra cotta is clay tile in various colors

2 grades of glazed structural tile: S-used with relatively narrow mortar joints; SS-used where the variation of face dimensions must be very small

two types: side construction and end construction

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31
Q

Stone is classified by…

A

the way it is shaped and prepared prior to installation

rubble: stone used with little or no shaping

squared stone: stone with slightly shaped edges resulting in vertical joints

ashlar: highly shaped, thick pieces of stone

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32
Q

Stone Masonry

A

• Building stone is obtained by taking rock from the earth and reducing it to the require shapes and sizes for construction
• Igneous rock: rock that was deposited in a molten state (granite, basalt)
• Sedimentary rock: deposited by the action of water and wind (limestone,
sandstone, brownstone)
• Metamorphic rock: formerly either igneous or sedimentary rock transformed by
heat or pressure (marble, soapstone, slate)

• Stone blocks are often used as exterior facing with a concrete masonry backup wall
• Stonework must stay clean, flashings must be plastic or nonstaining metal, work is
kept covered as much as possible
• Stonework can only be cleaned with mild soap, water, and a soft brush

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33
Q

• Stone is used in two fundamentally different ways in buildings:

A
  • Laid in portland cement mortar like bricks or concrete blocks. Avoid moisture penetration
  • Mechanically attached in large sheets to the structural frame and walls as thin facing (less common)
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34
Q

• Types of stone classification:

A
  • Rubble: unsquared pieces of stone
  • Ashlar: squared pieces of stone
  • Coursed: continuous horizontal joint lines • Uncoursed/Random: no horizontal lines
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35
Q

• Masonry accessories and anchors include:

A

• Strap anchors: galvanized steel attachment
• Dovetail anchors: splayed tenon that fits into the recess of a corresponding mortise
• Cramp anchors: used under coping stones at vertical joints to tie 2 stones together
• Pin anchor: anchor placed into a drilled hole and a pin is hammered in
• Threaded dowel: used at vertical/horizontal joints between panels to align and
maintain distance between panel and backup structure

36
Q

• Structural bonds for brickwork

A
  • Running bond: entirely of stretchers
  • English Bond: alternates course of headers and stretchers
  • Common Bond: header course every sixth course, head joints are aligned between the header and stretcher courses
  • Flemish Bond: alternates headers and stretchers in each course
37
Q

WHich type of masonry cement mortar has the highest compressive strength?

type M

type N

type O

type S

A

type M

type M mosrtar has a minimum average 28 day compressive strength of 2500 psi

type O has the lowest strength (350 psi)

38
Q

for exterior walls what type of mosrtar is commonly used

A

type N

39
Q

type S mortar is typically used for what type of applications

A

heavier loading on interior walls and exterior walls at or below grade, such as foundation walls, retaining walls, pavements, and patios

40
Q

when high strength mortar is required for heavy loads of for cases where the mortar will be exposed to severe saturated freezing, type ___mortar is used

A

S or M

41
Q

Type ___ mortar is used only for light loads and where freezing is not expected.

A

O

42
Q

in masonry walls, water is prevented from seeping back into the wall through capillary action by using

A

drips

Drips are extensions of through-wall flashing or projections below masonry units

43
Q

according to most building codes, horizontal reinforcement ir required every ___ inches

A

16 iches

the reinforcement may be a continuous truss or ladder type laid in the mortar joints

44
Q

What is the compressive strength for the following types of concrete mortar?

M

N

O

S

A

M - 2500 psi

S - 1800 psi

N - 750 psi

O - 350 psi

45
Q

What type of brick would most likely be specified for an eastern exposure in New Hampshire?

NW

FBX

MW

SW

A

answer - SW - severe weathering

NW - normal weathering

MW moderate weathering

FBX refers to the finish appearance

46
Q

Three courses of bull stretcher using standard brick and standard mortar joints equal

A

12 in

a bull stretcher is a brick laid on its face so that the width of athe brick is visible. With a width of 3 5/8 in and a mortar joint of 3/8, three courses would be 12 in . Three standard stretcher courses equal 8 in.

47
Q

If crakcing occurred along the joints of a brick wall in a generally diaginal direction from a window corner up to the top of the wall, what would most likely be the cause?

A

lack of vertical control joints

48
Q

vertical cracking is usually an indication thtat the brick wall is…

A

not able to move laterally, whcih is a condition caused by lack of vertical expansion joints

49
Q

What is the most important fire resistance propoerty of a CMU partition?

A

equivalent thickness

Concrete masonry partitions are usually hallow, so the actual thickness of the solid material, not the actual overall width, is used to rate the fire resistance of the unit

50
Q

What is a requirement for a door opening in a masonry partition?

a. bond beam
b. arch action
c. weep holes
d. flashing

A

a. bond beam

51
Q

reglets

A

horizontal grooves cast into concrete that allow a piece of flashing to be slipped inside and then across the airspace and through the brick for proper drainage and moisture control

52
Q

tuck pointing

A

a process used to repair failing mortar joints. it involves removing the deteriorated mortar to a certain depth and inserting new, compatible mortar into the space, then striking it with a new, water resistance edge treatment

53
Q

flashing should always extend at least ____ inches beyond the face of the brick and turned down at a ____ degree angle for proper drainage

A

3/4 inches

45 degree angle

if the flashing is terminated before the face of the brick, the moisture will sepp into the brick and mortar and can damage. the 45 degree bend provides a drip edge that leads the moisture away from teh face of the brick

54
Q

in order to achieve a workability equivalent to that of converntional cement-lime mortars, masonry cement mortars are formulated with

A

air-entraining admixtures that result in higher workability

  • results in higher air content in the cured mortat than cement lime mortar
  • reduces bond strength between mortar and masonry to half
  • masonry cement should not be used for wall that require high strength and low permeability
55
Q

mostar makes up ___% of a masonry wall

A

20

56
Q

type N mortar

A

general purpose mortar

  • balance of good bonding strength and workability
  • recommended for exterior veneers, nonloadbearing exterior walls, parapets, chimneys, and interior load bearing walls
57
Q

type S mortar

A
  • higher flexural bond strneght than Type N mortar
  • recommended for exterior reinforced masonry, exterior loadbearing masonry wall, and veneers and walls subject to high wind forces or high seiemic loads
58
Q

Type O mortar

A

low strength

-recommended mainly for interior nonloadbearing masonry and historic resotration work

59
Q

type M mortar

A

high strength morat with less workability than S and N

-recommended for masonry constrction below grade, masonry subject to high lateral or compressive loads, masonry exposed to high frost action

60
Q

mortar are specified under

A

ASTM C270

61
Q

mortar that was mixed less than ___ minutes prior to its stiffenings can be retermpered with water to make it workable again.

A

90 minutes

-mortar that is unused for more than 2.5 hours must be discarded as it has already begun to hydrate and can no longer be retermpered

62
Q

what masonry unit is most resistant to fire

A

brick

63
Q

WHen firing bricks do higher temperature produce darker or lighter bricke

A

darker

64
Q

types of molding processes for bricks:

A

soft mud: clay contains (20-30 % water content); molds are wetted (water struck) or dusted with sand (sand struck) to prevent clay from adhering to molds

dry press; used for clays thatshrink excessivley during drying (10% water content)

stiff mud: most commonly used today (12-15% water content) passed through vaccum to remove air pocket in pbrick; clay extruded though recangular die and wire-cut to from individual bricks

65
Q

brick weathing in the USA

A
66
Q
A

common or american

67
Q
A

english

68
Q
A

enlgish cross or dutch

69
Q
A

flemish

70
Q
A

running bond

71
Q
A

stack

72
Q

a good rule of thumb for designing corbels is that the projection for each course should not exceed…

A

half the course height; this results in a corbel angle of about 60 degrees to the horizontal and minimizes flexural stress in the bricks

73
Q

in RBM constrcution what are the two types of grouting

A

low lift: courses are built 4 feet at a time before grouting; for small construction; grouting by hand

high lift grouting: grouting is done a story at a time; require cleanouts at bottom; grout pumping machinery must be used

74
Q

external flashing

A

prevent moisture from penetrating into the masonry wall at its exposed top or where it intersects the roof

75
Q

internal flashin (aka concealed or through wall flshing)

A

catch water that has penetrated a masonry wall and drain it through weep holes back to the exterior

76
Q

flashing is required at every location where…

A

…the cavity in a masonry wall is interuppted

heads of windows and doors

window sills

helf angles

spandrel beams

77
Q

advantages of EIFS

A

masonry is prtoected from temperature extremes and can function effectively to stabalize the interior temperature of the building

78
Q

disadvantages of EIFS

A

thin stucco coatings are usually not very resistant to denting or penetration damage

  • EIFS is combustible
  • puncture damage and lapses in worksmanship can lead to sublsantial moisiture leakage into the walls
79
Q

flashings may be made of

A
  • sheet metal
  • modified ashpalt membranes
  • plastics
  • rubbers
  • composite sheets
  • sheet metal (most expensive and durable)
  • copper and stainless steel are best
  • galvanaized steel eventually rusts and deteriorates
  • aluminum and lead aren’t suitable (react with mortar)
80
Q
A
81
Q

What are the dimensions of a U.S. modular brick

A

7 5/8” long

3 5/8” thick

2 1/4” high

  • the units are sized to that three brick courses plus three 3/8” mortar joints are equal to 8 in
  • the length of a brick plus 3/8 in mortar also equals 8 in
82
Q

type M mortar should be specified for…

A

exterior applications at or below grade

83
Q

type N or S mortar is best used for….

A

exterior applications above grade and for interior load bearing walls

84
Q

type O mortar is well suited for…

A

interior and protected exterior non load bearing partitions

85
Q

a flush mortar joint is acceptable for exterior use because

A

there is no space for water to accumulate

86
Q

calculate the equivalent thickness of a 12 in concrete block that is 75% solids

A

answer: 8 3/4”

the equivalent thickness is a measure of the amount of concrete in a hallow core block

  • it is equal to the thickness that the block would be if it were the same heght and length by were cast without holes
  • this infor is often necessary for calculating fire resistance assemblies
  • a nominal 12 in concrete block is actually 11 5/8 in thick; multiply the actual thicness by the percentage of solids to arrive at equivalent thickness of thie block is 75% of 11 5/8 in or 8 3/4 in
87
Q

Calculate the skewback for the jack arch shown. the wall is two wythes thick

A

answer: 9 inches

skewback is the horizontal distance from the upper corner of the masonry opening to the opper outside corner of the jack arch.

-it is equivalent to 1/2 in per foot of span for each 4 in of span depth

skewback = (span/24)(arch depth/4 in )