Masonry

Question 1

Mortar

Answer 1

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

Question 2

masonry cement

Answer 2

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

Question 3

mortar types

Answer 3

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

Question 4

grout

Answer 4

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

Question 5

• Grades for Building and Facing Bricks

Answer 5

• 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

Question 6

brick masonry

Answer 6

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

Question 7

molding method for brick

Answer 7

• 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

Question 8

Types of Facing Bricks

Answer 8

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

Question 9

• Needle Beam:

Answer 9

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

Question 10

Hallow brick

Answer 10

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

Question 11

Wythe:

Answer 11

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

Question 12

Course:

Answer 12

a horizontal layer of bricks or other masonry units

Question 13

Stretcher:

Answer 13

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

Question 14

Header:

Answer 14

a brick laid to bond two wythes together

Question 15

Solider:

Answer 15

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

Question 16

Sailor:

Answer 16

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

Question 17

Rowlock:

Answer 17

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

Question 18

Name Brick laying positions

Answer 18

Question 19

name common mortar joints

Answer 19

Question 20

Expansion joints are required when structure is over

Answer 20

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

Question 21

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

Answer 21

1-2

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

Question 22

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

Answer 22

the wash

Question 23

Efflorescence

Answer 23

• 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

Question 24

Abutment/Construction/Isolation Joints:

Answer 24

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

Question 25

tuck pointing or repointing

Answer 25

- 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

Question 26

Concrete Masonry Units (CMU’s)

Answer 26

• 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.

Question 27

concrete blocks are considered solid when

Answer 27

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

Question 28

CMU dimension are based on...

Answer 28

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

Question 29

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

Answer 29

- 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

Question 30

Structural Clay Tile:

Answer 30

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

Question 31

Stone is classified by...

Answer 31

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

Question 32

Stone Masonry

Answer 32

• 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

Question 33

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

Answer 33

* 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)

Question 34

• Types of stone classification:

Answer 34

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

Question 35

• Masonry accessories and anchors include:

Answer 35

• 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

Question 36

• Structural bonds for brickwork

Answer 36

* 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

Question 37

WHich type of masonry cement mortar has the highest compressive strength? type M type N type O type S

Answer 37

type M type M mosrtar has a minimum average 28 day compressive strength of 2500 psi type O has the lowest strength (350 psi)

Question 38

for exterior walls what type of mosrtar is commonly used

Answer 38

type N

Question 39

type S mortar is typically used for what type of applications

Answer 39

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

Question 40

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

Answer 40

S or M

Question 41

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

Answer 41

O

Question 42

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

Answer 42

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

Question 43

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

Answer 43

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

Question 44

What is the compressive strength for the following types of concrete mortar? M N O S

Answer 44

M - 2500 psi S - 1800 psi N - 750 psi O - 350 psi

Question 45

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

Answer 45

answer - SW - severe weathering NW - normal weathering MW moderate weathering FBX refers to the finish appearance

Question 46

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

Answer 46

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.

Question 47

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?

Answer 47

lack of vertical control joints

Question 48

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

Answer 48

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

Question 49

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

Answer 49

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

Question 50

What is a requirement for a door opening in a masonry partition? a. bond beam b. arch action c. weep holes d. flashing

Answer 50

a. bond beam

Question 51

reglets

Answer 51

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

Question 52

tuck pointing

Answer 52

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

Question 53

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

Answer 53

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

Question 54

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

Answer 54

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

Question 55

mostar makes up \_\_\_% of a masonry wall

Answer 55

20

Question 56

type N mortar

Answer 56

general purpose mortar - balance of good bonding strength and workability - recommended for exterior veneers, nonloadbearing exterior walls, parapets, chimneys, and interior load bearing walls

Question 57

type S mortar

Answer 57

- 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

Question 58

Type O mortar

Answer 58

low strength -recommended mainly for interior nonloadbearing masonry and historic resotration work

Question 59

type M mortar

Answer 59

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

Question 60

mortar are specified under

Answer 60

ASTM C270

Question 61

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

Answer 61

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

Question 62

what masonry unit is most resistant to fire

Answer 62

brick

Question 63

WHen firing bricks do higher temperature produce darker or lighter bricke

Answer 63

darker

Question 64

types of molding processes for bricks:

Answer 64

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

Question 65

brick weathing in the USA

Answer 65

Question 66

Answer 66

common or american

Question 67

Answer 67

english

Question 68

Answer 68

enlgish cross or dutch

Question 69

Answer 69

flemish

Question 70

Answer 70

running bond

Question 71

Answer 71

stack

Question 72

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

Answer 72

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

Question 73

in RBM constrcution what are the two types of grouting

Answer 73

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

Question 74

external flashing

Answer 74

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

Question 75

internal flashin (aka concealed or through wall flshing)

Answer 75

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

Question 76

flashing is required at every location where...

Answer 76

...the cavity in a masonry wall is interuppted heads of windows and doors window sills helf angles spandrel beams

Question 77

advantages of EIFS

Answer 77

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

Question 78

disadvantages of EIFS

Answer 78

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

Question 79

flashings may be made of

Answer 79

- 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)

Question 81

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

Answer 81

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

Question 82

type M mortar should be specified for...

Answer 82

exterior applications at or below grade

Question 83

type N or S mortar is best used for....

Answer 83

exterior applications above grade and for interior load bearing walls

Question 84

type O mortar is well suited for...

Answer 84

interior and protected exterior non load bearing partitions

Question 85

a flush mortar joint is acceptable for exterior use because

Answer 85

there is no space for water to accumulate

Question 86

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

Answer 86

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

Question 87

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

Answer 87

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 )