Concrete & Masonry

Question 1

Mortar types

Answer 1

classic mortar:cement, lime (plasticizes, hydrates), sand, water\masonry cement: porland cement + pulverized lime (not as strong)
N: soft stone, ab. grade, ext., 750
S: below grade, better compression, 1800
M: hard stone, load bearing, highest compression, 2500
O: interiors, least strong
putty mortar: for compatibility w historic structures
grout: bonds masonry to reinforcing or fills cavities, has coarse or fine aggregate, up to pea gravel

Question 2

Brick

Answer 2

burned clay, shale or mix of them
facing (nice finish) vs. building/common
FBS: facing, with a little variation (color/size/texture)
FBX: facing, with not much variation
FBA: facing, but very random
SW: severe weathering
MW:moderate
NW: negligible
hollow brick: HBS, HBX, HBA
sizes: 3 5/8”x2 1/4”x7 5/8”, makes 4x8 when grout jt is 3/8”, from Norman-style brick
wythe = stack
course = horizontal line
bond pattern = how courses relate to each other
horizontal jt = bed jt, vertical jt = bed jt

Question 3

Brick laying

Answer 3

tool the mortar jt to compress it, make more weatherproof
construction jt/cold jt: isolates masonry from through wall elements like doors, windows
expansion jt: allows for thermal movement, often includes shelf angle and/or compressible joint fillerwhen vertical units need supporting
repointing/tuckpointing: re-mortaring brick
weight is borne at 60 deg angle over top of brick

Question 4

CMUs

Answer 4

concrete masonry units: hollow (>75%) or solid, load or non-load bearing
wxlxh: h:8/12/16 l/w:4/6/8/10/12 typ:8x8x16 (double a brick course)
needs horizontal reinforcing every 16” o.c.
equivalent thicknesses determined by code for fire ratings (as if no hollow core, eg)

Question 5

Brick wall types

Answer 5

single wythe, cavity wall, reinforced grouted masonry, veneer

Question 6

Other masonry types

Answer 6

structural clay tile: burned clay, hollow, load and nonload bearing, only used as backup at exterior walls, not weather proof, good all-in-one structure and finish at interiors, S: select, SS: select sizes (better)

terra cotta tile: ceramic veneer, harder denser, more weatherproof, lighter than stone, adhere or anchor to wall behind, keep water out of non-glazed parts

gypsum block: used for fire protection, old-school

glass block: air inside under vacuum, so insulates well, not fireproof

stone: rubble, slightly squared, ashlar: random or coursed, needs to be anchored to backer w wire/mortar or angle/bolt, can be thinner/veneered stone (adhered only)

Question 7

<p>Framework</p>

Answer 7

<p>oil/glue/plastic on plywood + wood framing, steel/prefab, FRP, plastic, foam</p>

<p>slip forming: not waiting for complete cure, wait 6-12"/hour, usu for v big jobs</p>

<p>flying forms: reused on floor after floor</p>

<p>insulating (ICEs), polystyrene, remain in place, waterproofing on earth side, gyp on inside, v low acoustical and air flow</p>

<p>costs the most for concrete constr, bc of labor</p>

<p>tolerance: usu .25" out of plumb in 10'</p>

Question 8

Reinforcement

Answer 8

for req added tensile strength, bars or wire fabric
bar number increases w bar size in 1/8” increments
is deformed to increase bonding
markings indicate grade, source mill, size, type
grades 40/50/60/75 are yield strengths in kips/in2
types: axle, rail, billet
min distance to surface, min dist to each other specified by SE, needs to allow aggregate to pass through
can be reg steel, galv steel, SS, epoxy coated
GFRP: glass fiber reinforced polymer, where no metal can be used, can be used for primary structure

Question 9

Cement

Answer 9

all is pretty much Portland now = lime (CaOH, CaOx, CaCOx), silica, FeOx, AlOx

type I: normal, type II: modest sulfate resistance, heat controlled (dams), type III: high early strength, type IV: not used, low heat, type V: sulface resisting for high alkaline exposure

excess water creates pores that decrease compressive strength, should be 0.35-0.40 per 1, can create laitance, low strength, chalky pools, must be removed

Question 10

Aggregates

Answer 10

fines: less than no.4 sieve (4 openings/inch), coarse: 3/4-1”, good to have a variety to air pockets not too large

should be 65-70% of volume

can use clay/shale/slag for lt.wt. concrete, pumice/cinders for insulating concrete

Question 11

Curing

Answer 11

design strength = compression at 28 days
12,000 psi is high strength, 2000-4000 psi is normal
give it ideal temp/hydration for 7 days-2 weeks (longer if in critical/weird places)
slump test: consistency and water ratio
cylinder test: 7 and 28 day compression test
core cylinder test: taken from structure directly
kelly ball test: ball dropped, measure how much it sinks
impact hammer test: nondestructive hardness test
k-slump: floating scale measures liquidity
CaCl moisture dome test, weighed after 60-72 hrs
hygrometer test/relative humidity
polyethylene sheet test, tape it down, does it bubble?
mat test, same but w pc of impermeable flooring
electrical impedence test: conductance tested
litmus or titration to test for pH, alkalinity is bad for conc, because is dissolves cement, emulsifies adhesives, can avoid by using better aggregates/SCMs

Question 12

Admixtures

Answer 12

air entraining agent: more workability, more durability bc resists freeze/thaw better, keeps things mixed
accelerator: speeds up hydration reaction, good for cold weather
retarder: slows hydration, lessens heat, good for big pours
waterproofing: reduces water perm
corrosion or shrinkage resistance
superplasticizer: increases workability wo adding water, makes higher strength conc.

Question 13

SCMs

Answer 13

supplementary cemetitious materials
fly ash: improves workability, from coal furnaces
GGBFs: ground granulated blast furnace slag, is stronger in long run, better to work, durable
silica fume: from silica/metal furnace, reduces permeability
pozzolan: volcanic ash, might be deposited, reduces permeability, increases strength

Question 14

Special concrete types

Answer 14

autoclave aerated concrete/AAC: precast with Al added, steam cooked, v lightweight, v airtight, but needs waterproofing, not strong

self consolidating concrete/SCC: no vibration needed, superplasticizer used, less labor, and earlier high strength

carbon fiber concrete: expoxy coated carbon fiber mesh instead of steel mesh reinf., thinner, lighter precast panels, less buffer to surface, so stronger despite thinness

ultra high performance/UHPC: high strength, low perm, v durable, 17-25000 psi, cement and silica fume and plasticizer plus alkali resistant glass or steel fibers, usually factory made, often cladding, can be very thin

poured gypsum deck

Question 15

Finishes

Answer 15

rough: plywood face shows, smooth: from hardboard, metal, smoother wood
form liner: smooth wood, metal, harboard, thin brick
sandblasted, scrubbed, acid wash, water jet: exposes aggregate
brush hammered: looks like meat tenderized
grinding: looks like terrazo
applied: stucco or plaster
smooth rubbed: carborundum abrasive used
grout cleaned: skim coat of grout to even out
strike off: use straight edge to cut
float: bring cement to top w vibration
light steel trowel: done after floating, compacts, smooths
hard steel trowel: even more smooth
superfloat: where wheels need to be fast
broom finish: swept over top to increase grip
stamped: embossed

Question 16

Concrete joints

Answer 16

control jts: 1/4” depth, saw cut or forms

construction jts: between pours, need waterstops

expansion jts: allows for thermal movement

isolation: prevents vibration conduction

Question 17

Prestressed concrete

Answer 17

pretensioning: mostly only for precast conc., where tendons are stressed, conc is poured, tension released as hardens, cambers, then load on makes it flat again

post tensioning: pour, stress as it hardens, keep under stress, load

Question 18

types of cement used in mortar

Answer 18

type I, type II, type III

Question 19

how long before having to discard mortar

Answer 19

2.5 hours

Question 20

water table brick

Answer 20

A water table is a projection of lower masonry on the outside of a wall slightly above the ground.It is both a functional and architectural feature that consists of a projection that deflects water running down the face of a building away from lower courses or the foundation.

Question 21

coping brick

Answer 21

used to protect the wall underneath

Question 22

jamb bricks

Answer 22

bricks tacked vertically along the opening

Question 23

difference between grout and concrete

Answer 23

grout is more fluid and pourable

Question 24

SW grade brick (severe weathering)

Answer 24

used for underground applications and for any climate. tougher brick

Question 25

MW grade brick (moderate weathering)

Answer 25

weather resistant and exterior only in warm areas

Question 26

NW grade brick (negligible weathering)

Answer 26

interior use only

Question 27

headers (bricks)

Answer 27

rotated 90 degrees to tie two wythes of brick together

Question 28

centering

Answer 28

temporary structure erected to support an arch while being constructed

Question 29

quoins

Answer 29

corner stones

Question 30

stone masonry vs stone cladding

Answer 30

masonry is stacked and cladding is attached to building with anchors, skin

Question 31

ashlar vs rubble

Answer 31

ashlar: rectangularrubble: non rectangular

Question 32

lewis pins

Answer 32

lift stones

Question 33

starp anchors

Answer 33

attach the mortar to the wall between courses of stone

Question 34

concrete block size (common in US)

Answer 34

8x8x16

Question 35

how do we reinforce concrete block walls horizontally

Answer 35

lay small diameter welded grid steel every few courses for extra load bearing resistance to cracking and sesimic stain

Question 36

how do we supply vertical reinforcing in concrete masonry

Answer 36

every three blocks, we set rebar and fill the cavities containing the rebar with grout

Question 37

how do we span over a window or door in concrete masonry

Answer 37

steel lintel, reinforcer block lintel, precast concrete linter

Question 38

efforescence

Answer 38

white, crystalline deposit of water soluble salts on the surface of the brick masonry

Question 39

What are the different types of Brick?

Answer 39

• Building Brick: Cored structural bricks, the ones with holes, are for construction. The holes are there to save material and weight.
• Face Brick: These are the sold bricks that face the outside of your building. They are available in various colors, sizes, and shapes.
• Firebrick: This type of brick is heat-resistant and made for fireplace or heat-sensitive construction.
• Brick Pavers: To be used for sidewalks, patios, and edging.
• Antique or Tumbled Brick: Instantly achieve the impression of antiquity with vintage-style brick texture.
• Brick Veneer: Non-load-bearing interlocking brick siding (about 1/2” thick); requires no mortar. These are available for interior or exterior use.

Question 40

What are the three grades of brick?

Answer 40

The grades of these are:
* Severe Weathering (SW): Able to experience freeze and thaw cycles; perfect for cold climates.

• Moderate Weathering (MW): Tolerance to frost and freezing; used for outdoor walls.
• No Weathering (NW): For indoor use only.

Question 41

sill bricks

Answer 41

bricks going horizontally along the opening

Question 42

What are the five types of portland cement according the the American Society for Testing and Materials (ASTM)?

Answer 42

The five types of these include the following

Ordinary (Type I)
Modified (Type II)
High-early-strength (Type III)
Low-heat (Type IV)
Sulfate-resistant (Type V)