Materials and Assemblies for the Envelope Flashcards
1
Q
What are two most common types of soil tests for bearing capacity?
A
- borings
2. test pits
2
Q
What is the most common type of borehole test?
A
Standard Penetration Test = A type of borehole test that measures the density of granular soils and some clays.
A 2 in. diam. sampler is driven into the bottom of the borehole by a 140 lbm hammer falling 30 in. The number of blows (N) is recorded to drive the cylinder 12 in. Samples are tested in the lab.
3
Q
What are Test pits?
A
A type of soil test that uses trenches dug on site to allow visual inspection of the soil strata and direct collection of undisturbed samples. Practical limit on depth is 10 ft
4
Q
What are wash borings?
A
A type of soil test in which samples are gathered via 2 in to 4 in pipe through which water jet is forced to push up soil. Most useful for soils too hard for an auger test. Can extend to 100 ft or more.
5
Q
What are auger borings?
A
A type of soil test in which an auger is used to pull up soil samples. Best used in sand or clay for shallow or intermediate depths since the auger cannot penetrate hard obstructions like bedrock or hardpan soil.
6
Q
What are soil load tests?
A
a platform is built on site and incremental loads are placed on it. The amount of settlement during a given period is observed until settlement becomes regular after repeated loading.
7
Q
What is a Karst?
A
Karst = landscape in which soluble rocks such as limestone, dolomite, and gypsum have dissolved and formed caves/voids below the surface, which can cause sinkholes.
8
Q
What are 8 methods to increase bearing capacity and/or decrease settlement of the soil?
A
- Drainage
- Fill
- Proctor test
- Compaction
- Densification
- Surcharging
- Mixing
- Geotextiles
9
Q
How can drainage help to increase bearing capacity and/or decrease settlement of the soil?
A
draining water from soil can increase soil strength and prevent hydrostatic pressure
10
Q
How can fill help to increase bearing capacity and/or decrease settlement of the soil?
A
removing poor soil and replacing with fill. Fill needs to be compacted
11
Q
How can a Proctor test help to increase bearing capacity and/or decrease settlement of the soil?
A
determines standards for compaction
12
Q
How can compaction help to increase bearing capacity and/or decrease settlement of the soil?
A
compacting existing soil makes it stronger
13
Q
How can densification help to increase bearing capacity and/or decrease settlement of the soil?
A
type of on-site compaction involving vibration, dropping heavy weights, pounding piles into the ground and filling voids with sand.
14
Q
How can surcharging help to increase bearing capacity and/or decrease settlement of the soil?
A
preloading the ground with fill material to cause consolidation and settlement before building. Often costly and takes time.
15
Q
How can mixing help to increase bearing capacity and/or decrease settlement of the soil?
A
mixing a layer of sand or gravel with existing less stable soil.
16
Q
How can geotextiles help to increase bearing capacity and/or decrease settlement of the soil?
A
used to stabilize engineered fill below footings, stabilizing marginal soils under paving, and erosion control
17
Q
Where should building footings be located in relation to the frost line?
A
footings should be located below the frost line to prevent the structure from lifting up.
18
Q
When should you use a mat slab (raft) foundation?
A
when soil bearing is low or where loads are heavy in relation to soil pressures.
19
Q
When should you use pile footings?
A
When soil near grade level is unsuitable for spread footings. They transmit building loads through the unsuitable soil to a more secure bearing with end bearing or side friction.
20
Q
When should you use grade beam foundation?
A
Where expansive soils or clay (such as bentonite) are encountered near the surface
21
Q
What is the difference between a pile and a pier?
A
pile = timber, steel, or precast concrete that are driven into the ground with hammers piers = drilled hole that is filled with concrete
22
Q
What is grading? What is the difference between rough grading and finish grading?
A
Grading = the modification of contours of the site according to the grading plane.
Rough grading = the moving of soil prior to construction to approximate levels of final grades. Also includes adding or removing soil after construction to the approximate final grades, within 6”-12”.
Finish grading = the final moving of soil prior to landscaping or paving, where level of earth is brought to within 1” of desired grades
23
Q
What are two common methods of excavation if excavation is too deep for a slope cut? What is the main difference between the two?
A
- shoring (soldier piles)
- braced excavation
Shoring with soldier piles uses wide flange and breast boards to hold up the earth. The wales are reinforced with tiebacks into the earth.
Braced excavation uses wood or steel sheathing to hold up the earth. The wales are reinforced with diagonal rakers that are anchored to the bottom of excavation.
24
Q
What is underpinning?
A
a method to temporarily support existing foundations while they are being repaired or strengthened or when they are being extended to a lower level. Uses needle beams supported by adjacent grade and hydraulic jacks to support the building.
25
What is the most common forming material for cast in place concrete?
plywood
26
What are alternate forming materials for plywood for cast in place concrete?
prefabricated steel forms - strength and reusability. Good for one-way joist systems, waffle slabs, and other special shapes
glass-fiber-reinforced plastic, etc - can be manufactured with patterns embedded within.
27
What is slip forming?
A type of concrete formwork that moves as the concrete cures. It is used to form continuous surfaces (tunnels or high rise building cores).
28
What are flying forms?
A type of concrete formwork made from large fabricated sections of formwork that are removed once the concrete has cured and reused in forming an identical section above. Used in buildings with highly respective units (hotels or restaurants).
29
What are insulating concrete forms (ICFs)? What is their main benefit? Where are they commonly used?
Insulating concrete forms (ICFs): polystyrene foam forms that provide the formwork for poured concrete and remain in place after the concrete cures.
They speed construction and provide insulation in one operation.
Often used in single family residential and small commercial. Can be used for the basement portion of the building only, or up to 2 stories above grade.
30
What are three basic varieties of ICF systems?
Blocks = foam blocks the size of concrete blocks
Panels = flat foam panels 4 ft x 12 ft
Plank systems = flat forms 12 in. high and from 4 ft to 8 ft long
31
What is one of the biggest expense for CIP concrete?
the formwork
32
What is the construction tolerance for columns, piers, walls?
1/4" in any 10' length
33
What is the construction tolerance for ceilings, beam soffits, and slab soffits?
1/4" in any 10' length
34
What is the construction tolerance for elevated, formed slabs?
3/4"
35
What are 2 methods to implement if hydrostatic pressure is an issue?
Place a layer of gravel against the wall
| Place a geotextile material against the wall
36
Where should the vapor barrier be placed in a slab on grade assembly? why?
Below the slab and on top of the sand/gravel cushion layer/subbase. To avoid moisture migration through slabs on grade.
37
When should you specify low water-cementitious materials ratio (w/cm ratio)?
to reduce water problems inside the building.
38
What is the min and max w/cm ratio?
Min w/cm ratio = 0.30 to 0.35 (to produce workable mix)
| Max w/cm ratio = 0.45 to 0.50 (to avoid being watery)
39
For how long should concrete slabs dry/cure before sealants or resilient flooring is installed?
min six weeks
40
What will occur in cement if too much water is added?
laitance = chaulky surface deposit of low-strength concrete. Must be removed if new concrete is to be poured on top of it.
41
when can you use a w/cm ratio of 0.25?
w/cm ratio of 0.25 is used where high strength is required, but it must be with a superplasticizer to make the mix workable
42
when can you use a w/cm ratio of 0.55?
w/cm ratio of 0.55 is workable for common residential walks and driveways
43
What 4 types of rebar should you use if corrosion presents a problem, such as in highways or high voltage transformer vaults?
1. Stainless steel = use in conditions of extreme corrosion resistance or nonmagnetic characteristics are needed. High cost
2. Galvanized steel
3. Epoxy-coated rebar = use where corrosion presents a problem (road, parking, marine). Less expensive than stainless steel.
4. Glass-fiber-reinforced polymer rebar (GFRP) = use where corrosion is present or nonferrous reinforcement is needed. Cannot be used in primary structural members since it has different properties than steel.
44
What are the 3 ingredients in concrete?
cement
fine and course aggregates
water
45
What will be the result of too much water in concrete mix?
it will decrease the concrete's strength. excess water remains in the paste and forms pores that cannot resist compressive forces.
46
What are the 5 types of cement?
Type I = standard / normal cement
Type II = modified cement
Type III = high-early-strength cement = sets quickly with higher heat hydration (good for cold-weather)
Type IV = low-heat cement = very slow setting, not commonly used
Type V = sulfate-resisting cement = used for structures that will be exposed to water or soil with high alkaline content
47
What is welded wire fabric? When should you use it for reinforcement?
cold-drawn steel wires set at right angles and welded at intersections. Use for temperature reinforcement in slabs.
48
What percentage of concrete mix is aggregate? What is the goal for deciding how much aggregate to use?
65-75%
Goal is use min amount of cement (because it’s expensive) with a combination of aggregates sizes that fill the most of the volume and still achieve the desired strength
49
What are aggregates typ made of?
Aggregates are usually made of sand and gravel, but may also include expanded clays, slags, and shales in lightweight structural concrete
50
How much does standard concrete weight in lbm/ft3? Lightweight concrete?
150 lbm/ft3
| 50 lbm/ft3
51
What are the 5 factors that determining proportions in a concrete mix?
```
Strength
Workability
Durability
Economy
Sustainability
```
52
What is the design strength of concrete?
Design strength = Strength of concrete is specified by its compressive strength after it has hardened/cured for 28 days
53
What are 4 typical design strengths?
2000 psi
3000 psi (most common)
4000 psi
12,000 psi available for special applications
54
What are admixtures?
= chemicals added to concrete to impart certain qualities
55
Air-entraining agent
an admixture that increases workability and durability of the concrete, and improves its resistant to freezing and thawing cycles
56
Accelerator
an admixture that speeds up hydration of the cement so that the concrete achieves strength faster. Allows faster construction and reduces the length of time needed for protection in cold weather.
57
Plasticizer
an admixture that allows for higher-strength concrete by reducing the amount of water needed while maintaining the needed consistency
58
Retarder
an admixture that slows down the setting time to help reduce the heat of hydration. Counteracts the accelerating effect of hot weather on concrete setting.
59
Waterproofing agent
an admixture that decreases the permeability of the concrete
60
What are Supplementary cementitious materials (SCMs)?
added to concrete as part of total cementitious system and also impart desirable qualities to the mix
61
Fly ash
a supplementary cementitious materials (SCMs) that improves workability, reduces temperature rise, reduces quantity of total cement needed, minimizes bleeding, reduces permeability, inhibits alkali-silica reaction (ASR), and enhances sulfate resistance.
62
Ground-granulated blast-furnace slac (GGBFS)
a supplementary cementitious materials (SCMs) that is substituted for portland cement in different ratios. Good for large pours in hot weather.
63
What are 4 attributes of Ground-granulated blast-furnace slac (GGBFS)?
1. Improves workability
2. Decreases need for water
3. Increases setting time of concrete
4. Slower setting time -- continues to gain strength after 28 days and ultimately has higher compression strength than portland cement concrete
64
Silica fume
a supplementary cementitious materials (SCMs) that:
1. Decreases permeability
2. Increases compressive strength
3. Improves abrasion resistance
4. Reduces bleeding
65
Pozzolan
a supplementary cementitious materials (SCMs) that is used as partial replacement for portland cement:
1. Decreases permeability
2. Increase strength
3. Improve resistant to ASR and sulfate attack
4. Can be made from shale, clay, volcanic ash
66
What are autoclave aerated concrete precast concrete blocks?
Sustainable alternative to concrete in nonbearing walls and low rise structures
- 10 in. tall x 25 in. long and thicknesses 4 in, 8 in, 10 in, made with aluminum powder
- 1/5th density of conventional concrete
67
What is self-consolidating concrete (SCC)?
A concrete product in which no vibration needed, can be used with a superplasticizer admixture
- Finishes faster, requires less labor, and increases productivity
- Used for cast-in-place conditions
68
What is Carbon fiber concrete?
A concrete product that uses epoxy-covered carbon fiber mesh instead of standard steel mesh for secondary steel reinforcement.
- Used to make precast concrete panels thinner and lighter
- Require smaller foundations
- Reduces transportation costs
- Speeds erection process
69
What is ultra high performance concrete?
A concrete product that is high strength, low water absorption, and high resistant to chemical degradation
- Compressive strength = 17,500 psi to 25,000 psi
- Cement, sand, water, silica fume, plasticizers, and alkali resistant glass fibers or steel fibers
- Typically precast
70
What is the slump test?
Measures the consistency of concrete
- On-site test that poures concrete into a cone shaped form, removes the form, and measures how much the concrete slumps in inches.
- 2"-6" of slump is ideal.
- Too much slump = excessive water in the mix
- Too little slump = mixture will be difficult to place properly
71
What is a K-slump test?
measures consistency of concrete
| Similar measure to traditional slump test, but with tube containing a floating scale on poured concrete
72
What happens if concrete dries/cures too fast?
It can lose up to 35% or more of its strength
73
What is heat of hydration?
the heat that concrete produces while it cures.
74
What is the Kelly ball test or ball penetration test?
measures consistency of concrete
a steel ball is drop onto a slab of freshly laid concrete.
Amount of penetration of ball is measured and compared to 1/2 of the values of the slump test
75
What is the Cylinder test?
measures compressive strength
| as concrete is placed, samples are put in a cylinder mold and tested in the laboratory.
76
What is the Core cylinder test?
= used when the structure is in place and cured but needs to be tested
Cylinder is drilled out of concrete and tested in the lab
77
What is the Impact hammer test?
Tests concrete strength after it has hardened. An on-site, nondestructive test that measures strength through rebound of hammer.
78
When should testing concrete for moisture content and alkalinity be done?
before flooring can be laid on top of concrete
79
What is the maximum limit for moisture emission in cocnrete?
3.0 lbm per 1000 sf per 24 hours when exposed to 73 deg F and 50% relative humidity
80
Calcium chloride test or moisture dome test
one of the most common tests for testing moisture in concrete since it is inexpensive and easy to complete
81
Hygrometer test or relative humidity test
A test that determines moisture emission from concrete by measuring relative humidity. Flooring should not be installed if relative humidity < 75%
82
Polyethylene sheet test
A qualitative tests that measures moisture in concrete. An 18x18 sheet of plastic is sealed to the floor. After 16 hours min, floor and sheet are inspected. Presence of visible water indicates concrete is not dry enough yet.
83
Mat Test
A qualitative tests that measures moisture in concrete. A 24x24" sample of vapor retardant floor finish is applied and sealed to the concrete. After 72 hours a visual inspection is made. If mat is firmly bonded or if removal is difficult, the level of moisture is low enough for floor installation.
84
Electrical impedance test
Determines moisture content of the concrete with a meter that measures percentage of moisture content in the slab.
85
What is the normal pH of concrete?
12.0 - 13.3 (>7 so alkaline)
86
What are two problems that alkalinity can cause in concrete?
1. High alkalinity on the surface of a slab can damage flooring installation by causing adhesives to return to liquid states
2. Alkaline-silica reaction (ASR) = a high alkaline content starts to dissolve the sand and rock in the concrete
87
What are 4 ways to reduce the risk for ASR (Alkaline-silica reaction)?
1. Specify aggregates that are not susceptible to ASR
2. Use low lime cement
3. Properly cure the concrete
4. Do not finish the concrete with a hard trowel surface
88
What is a pH test for concrete? What are maximum pH levels for flooring installation?
Tests the surface of concrete that will come into contact with adhesives or flooring coatings.
pH of 8.5 is ideal for flooring installation, which is about the minimum that concrete can have. A pH of 9 is the maximum acceptable.
89
What is a titration test?
A laboratory test that determines levels of alkalinity in concrete.
90
What is a rough form finish for concrete?
as-is when forms are removed. Used when concrete will not be visible.
91
What is a smooth form finish for concrete?
formwork is smoother and more planned out.
92
What is a smooth form finish for concrete?
Architectural finishes = used when concrete will be exposed
93
What is segregation of concrete? What is one of the typical causes?
The separation of the aggregates, water and sand from each other during placing.
Dropping concrete long distances from the conveying device. Typically concrete should be dropped a max of 5 ft
94
What is honeycombing in concrete?
the formation of air pockets within the concrete and next to forms. Avoid by consolidating (vibration)
95
What is an Architectural finish for concrete?
used where concrete will be exposed and appearance is a consideration. There are several varieties.
96
What is a form liner finish?
A type of Architectural finish for concrete that gives a pattern via liners placed in the formwork. Can be plastic, wood, metal, or custom to give any sort of patter desired.
97
What is a scrubbed concrete finish?
A type of Architectural finish for concrete in which the surface is scrubbed with a wire or fiber brush to remove some of the surface mortar and expose the coarse aggregate.
98
What is an acid wash concrete finish?
A type of Architectural finish for concrete in which the surface of concrete is wetted with muriatic acid to expose and bring out the full color of the aggregate.
99
What is a water jet concrete finish?
A type of Architectural finish for concrete in which high-pressure water jet mixed with air is used to remove some of the mortar and expose the aggregate.
100
What is a bush hammering concrete finish?
A tooled finish that gives a rugged, heavy texture by removing a portion of the surface with a manual or electric hammer with a head that has rows of small pyramids.
101
What is a grinding concrete finish?
A tooled finish that uses a grinder to smooth out the surface of the concrete, giving it a similar appearance to terrazzo.
102
What is an applied concrete finish?
A tooled finish that includes the application of other materials, such as stucco, to the concrete.
103
What is a sandblasted concrete finish?
A tooled finish that are produced by removing surface material from the concrete, exposing fine and coarse aggregates to varying degrees depending on whether the sandblasted finish is light, medium, or heavy.
104
What are rubbed concrete finishes? What are 2 types?
Gives concrete a smooth, uniform, durable finish. Labor intensive.
1. smooth = Surface of concrete is wetted and rubbed with an abrasive to produce a uniform color and texture.
2. grout cleaned = Grout is applied over the concrete and smoothed out to produce a uniform surface that conceals defects.
105
What does it mean to 'strike off' a concrete slab?
the first finishing operation after a slab is poured in which a straight edge (metal or wood) is drawn across the form to yield a roughly level surface.
106
What does it mean to 'float' a concrete slab?
| What is a float finish?
the second finishing operation after a slab is poured IF a smooth surface is required. Floating brings the cement paste to the surface where it is consolidated and smoothed over the coarse aggregate.
If no further finishing work is done after this, it's considered a float finish. Gives a sandpaper-like texture that is appropriate for exterior surfaces or where smooth surfaces are not needed.
107
What is a light steel-troweled concrete finish?
A finish used for concrete slabs that is achieved by using a steel trowel several hours after floating to further consolidate concrete.
108
What is a hard steel-troweled concrete finish?
A finish used for concrete slabs that continues consolidation of concrete and greatly densified the top 1/8 in. to make a very smooth surface.
109
What is a broom finish? Where is it useful?
A finish used for concrete slabs that can be done after floating by running an industrial broom with medium bristles over the concrete to dislodge fine aggregates and produce a rough-textured surface.
Useful for slip-resistance on outdoor slabs
110
What is a superflat floor finish?
A floor that has a hard steel-troweled finish. "superflat" refers to the smoothness and levelness of concrete. Often used in industrial warehouses.
111
What is a stamped concrete slab finish?
A finish used for concrete slabs that gives the slab an embossed surface with a plastic stamp. Used in locations where concrete is a decorative elements, like patios.
112
What are the 4 main types of concrete joints?
1. Control
2. Construction
3. Expansion
4. Isolation
113
What is a control joint in concrete?
A weak section intentionally created in the slab so normal temperature and stress cracking will occur at the joint instead of random locations. Depth of joint is ¼ of the slab thickness, made while concrete is still wet.
114
What is a construction joint in concrete?
occurs when there are two successive pours. Should be located at point of minimum shear
115
What is a expansion joint in concrete?
allows entire sections of concrete structure to move independently of each other. Extends through the entire structure -- walls, floors, roof, etc. Achieved with a preformed expansion joint filler that is 1" to 3" wide and an expansion joint cover that allows for movement.
116
What is an isolation joint in concrete?
allows two adjacent sections to move independently as each other with a premolded joint material. Used to separate columns from slabs and slabs from foundations. Achieved with an expansion joint filler htat is 1/2" wide.
117
What is a concrete sealer?
A proprietary product applied to concrete to protect against weather and water penetration, provide resistance to chemicals, prevent dusting, or harden the surface.
118
What are 2 general types of concrete sealers?
1. Coating types = dry as a surface film
| 2. Penetrating types = seep into concrete pours and do not wear off as easily
119
Lift-slab construction
A technique for multistory construction in which entire floor sections are cast on the ground, one on top of the other, around pre-constructed columns. Bond breaker is applied between pours. Slabs are lifted up and welded to columns.
120
What are 4 reasons an architect might chose masonry over concrete?
1. Masonry is strong in compression and fire resistant
2. No formwork or time to set
3. More cost effective in many applications
4. Aesthetic qualities
121
The 3 aspects of mortar that must be considered in its use are:
1. components of mortar
2. types of mortar
3. grout
122
What are the components of mortar?
cement (typ portland cement)
lime (plasticizes and increases resilience and water retention)
sand
water
123
What is masonry cement?
a mixture of portland cement and pulverized limestone. Not as strong or expensive as portland cement, but has great plasticity. Use in low-rise building veneers and interior non-load-bearing applications.
124
What is nonstaining cement?
use for marble, limestone, terracotta, cut stone, and glazed brick.
125
What are the 4 basic types of mortar?
N = most common for exterior, above-grade walls exposed to severe weather
S = has higher compressive strength and is thus suitable for at- or below-grade applications
M = highest compressive strength and recommended for harder stone and walls bearing heavier loads
O = limited to interior non-load-bearing walls and historic structures
Never use a higher strength mortar that is needed
126
What is the difference between mortar and grout?
Mortar binds masonry units together where as grout is used to either fill in gaps or wall cavities to ond masonry to the reinforcement.
127
What are two basic types of brick?
1. facing brick
| 2. building brick (common brick)
128
What is the difference between facing brick and building brick?
facing brick is used for exposed locations where appearance and uniformity of size are important. Building brick is made without regard for color or special finish.
129
How is building brick graded? What are the 3 grades?
Graded according to resistance to exposure. The grades reflect the ability of brick to resist freeze-thaw cycles:
1. SW (severe weathering)
2. MW (moderate weathering)
3. NW (negligible weathering)
130
What are the 3 types of facing brick?
1. FBS (wide range of color and various in size are acceptable)
2. FBX (high degree of mechanical perfection, narrow color range, and minimal variation in size)
3. FBA (nonuniform in color, size or texture)
131
What grades are hollow brick available in?
| What are the 3 types of hollow brick?
Available in SW and MW grades
HBS (range of size and colors)
HBX (high degree of mechanical perfection, narrow color range, and minimal variation in size)
HBA (nonuniform in color, size, and texture)
132
Common size brick
= 4in. thick x 8in. Long @ 3 courses = 8 in.
133
Roman brick
= 4in thick x 12 in long @ 2 courses = 4 in.
134
Norman brick
= 4in thick x 12 in long @ 3 courses = 8in.
135
Belt course
= continuous band of masonry across the facade or around the building
136
What is a wythe of brick?
a continuous vertical section of a wall one masonry unit in thickness.
137
What are the 3 mortar joints recommended for exterior use?
1. concave (rounded and pushed in)
2. flush
3. vee ('v' shaped and pushed in)
138
What is a weather struck mortar joint? When is it acceptable to use?
angled in at the top of the joint.
| sometimes acceptable for exterior use, but not ideal.
139
What is a construction joint in brick masonry?
also known as a cold joint, it isolates masonry from through-wall elements like doors and windows
140
What is an expansion joint in brick masonry? How far should they be spaced?
Where should horizontal expansion joints be placed?
accommodates natural expansion/contraction by separate two sections of masonry and filling with a backing covered with a sealant.
Spaced every 15ft to 25 ft and at places where the wall changes direction, height or thickness.
Horizontal expansion joints should be placed below beams or slabs or shelf angles that support the brick
141
What is a through-building expansion joint in masonry?
Larger and used to separate two sections of a building. Spaced every 100ft - 150 ft
142
What is a single wythe wall?
one layer of brick that acts as either a load-bearing or non-loading bearing wall. Nonreinforced, so max. ratio of unsupported height to thickness = 20: 1.
143
What is a cavity wall?
consists of two wythes of brick separated by an air space and tied together with galvanized metal wall ties or continuous horizontal reinforcement placed 16 in on center vertically. inside wythe is often made from CMU
144
What is a reinforced grouted masonry wall?
consists of two wythes of brick separated by a cavity that contains vertical and horizontal reinforcing bars and is completely filled with grout. Compared to cavity walls can carry heaver loads, have higher unsupported heights, and are better able to resist lateral loading.
145
What is one of the most important considerations in designing a brick wall?
watertightness
146
where should base flashing be installed on a brick wall?
at the bottom of the exterior wythe and extend up 8"-10"
147
How are most openings in masonry walls spanned?
with steel lintels -- should bear on masonry min 6"
148
What is Efflorescence?
= crystalline deposit of water-soluble salts on the surface of the brick that occurs when water that has seeped into the brick evaporates. Does not harm it. Can be wiped off with a special solution or water.
149
How can efflorescence be avoided?
1. using materials with few or no soluble salts
2. forming tight joints
3. detailing the wall to avoid water penetration
150
What is tuckpointing or repointing?
Replacing mortar that has fallen out
151
What are the 4 classifications of concrete block (CMU)?
1. hollow, load bearing
2. solid, load-bearing
3. hollow, non-load-bearing
4. solid, non-load-bearing
where
hollow units are < 75% solid material
solid units are > 75% solid material
152
How are CMUs sized?
Sizes are based on 4” module, given in width x height x length
ex 8 in x 8 in x 16 in (nominal) = 7 5/8 x 7 5/8 x 15 5/8 (actual)
153
What are the 4 typical shapes of CMU?
Stretcher = middle piece
Corner block = end piece
Jamb block = at a jamb
Bond beam = shaped like an extruded U, serves as lintel and resist lateral loads and provide bearing for floors/roofs
154
What is the equivalent thickness of a CMU?
the solid thickness that would result if the concrete contained in a hollow unit were recast without core holes. Fire rating is based on this value.
155
What is casting (metal)?
pouring molten metal into formwork
156
What is metal rolling?
| Whare are 2 types?
passing metal through rollers to produce the needed shape
1. Cold rolling = increases strength and elastic limit, but decreases ductility
2. Hot rolling = eliminates flaws
157
What is extruding (metal)?
pushing metal through a die to form a shape
| Common for doors and window frames
158
What is drawing (metal)?
Drawing = pulling metal through a die to form a shape
| Improves strength and surface qualities
159
What is annealing (metal)?
Annealing = process in which metal is heated and cooled slowly to increase ductility
160
What is quenching (metal)?
Quenching = process in which metal is heated and cooled quickly to increase strength
161
What is tempering (metal)?
Tempering = process in which metal is heated and slowly cools to increase strength and workability
162
What is case hardening (metal)?
Case hardening = hardens the exterior of the steel while keeping the core softer
163
3 types of metal finish categories:
1. Mechanical finishes = altering the surface of the metal
2. Chemical finishes = altering the surface of the metal with chemicals
3. Coatings = to protect or decorate
164
What is galvanic action?
Galvanic action = corrosion resulting from dissimilar metals coming into contact with each other in the presence of moisture
165
What are 2 ways to avoid galvanic action?
1. Use identical metals when they are in contact
| 2. Separate dissimilar metals with non conducting materials such as neoprene, plastic, or rubber
166
2 classifications of metals:
Ferrous = contain a substantial amount of iron
Nonferrous = do not contain iron
167
What are 2 types of iron?
1. Wrought iron = soft, ductile, and resistant to corrosion. Use is limited to ornamental work.
2. Cast iron = very hard and brittle. Used historically in columns and beams.
168
What are 4 types of ferrous metals?
1. Iron
2. Steel = high ductility, so good for earthquake resistant structures (As carbon is added, strength increases but ductility decreases)
3. Stainless steel = highly corrosion resistant and high strength
4. Steel alloys
169
What are 3 types of nonferrous metals?
1. Aluminum
2. Copper
3. Copper alloys (bronze and brass)
170
What is the difference between bronze and brass?
```
Bronze = copper + tin
Brass = copper + zinc
```
171
What is aluminum?
A type of nonferrous metal with high strength to weight ratio, but high embodied energy
172
What is copper?
A type of nonferrous metal with high resistance to corrosion, workable, and high electrical conductivity
173
What are the 2 metals used in structural applications?
1. Steel (most common)
| 2. Aluminum (limited to small structures or portions of structures)
174
What is the shape of a wide flange beam?
Nomenclature?
Use?
Wide flange = H shape
Nomenclature = W(depth)x(weight) = W18x85
Can be used for columns or beams
175
What is the shape of an I beam?
Nomenclature?
Use?
I-beams = I shape with sloped horizontal pieces
Nomenclature = S(depth)x(weight)
Used for beams only
176
What is the shape of a channel section?
Nomenclature?
Use?
Channel sections
Nomenclature = C(depth)x(weight)
Seldom used alone for beams or columns
Often used to frame openings or for stair stringers
177
What is the shape of structural tees?
Nomenclature?
Use?
Structural tees = wide flange or I-beam cut in half
WT = wide flange (ex. WT9x57 is taken from a W18x114)
ST = i beam
Often used for chords of steel trusses
178
What is the shape of steel angles?
Nomenclature?
Use?
Steel angles = either with equal or unequal legs
Nomenclature = L(length of angles)x(thickness of legs) = L3x3x3/8
Used in pairs members for steel trusses or singly as lintels
179
What is the difference between a steel bar and a steel plate?
Bars vs plates
Bars = 6in or less
Plates = 8 in or wider
180
What are the 3 types of open web joists? What is the nomenclature?
K series = standard
LH series = long span
DLH = deep long span
Nomenclature = (depth)(series)(chord type) = 36LH13
181
What are the available stud depths of light gage metal framing? Available joist depths?
Available stud depths = 1 ⅝, 2 ½, 3 ⅝, 4, and 6 inches
| Available joist depths = 6 in - 14 in
182
What is the difference between rough carpentry and finish carpentry?
Rough carpentry = structural framing, shetahing, block etc. Won't’ be seen
Finish carpentry = exposed, finished lumber
183
What is the difference between soft wood and hard wood?
Softwood = comes from conifers
Used for structural and rough carpentry
Hardwood = comes from deciduous trees
Used for finish elements
184
How to calculate the moisture content of wood?
Moisture content = weight of water in the wood as a fraction of the weight of water in oven-dried wood
185
What is the fiber saturation point of wood?
Fiber saturation point = the point at which wood is dimensionally stable, where the cell walls are completely saturated but no water exists in the cell cavities. As wood dries below this point it begins to shrink
186
What is platform framing?
Platform framing = uses separate studs for each floor of the building
Advantage = shorter studs cost less and floors can be completed and used for constructing the next floor
187
What is balloon framing?
Balloon framing = uses continuous wall studs from foundation to the second floor
Advantage = vertical shrinkage is minimized
188
What does it mean to bonderize steel?
to coat it with an anticorrosive phosphate solution in preparation for the application of paint enamel, or lacquer
189
How does the percentage of carbon affect the strength and ductility of steel?
As carbon is added, the strength increases but ductility decreases.
190
What is the most common type of steel?
ASTM A992.
| yield point = 50 psi
191
What is Type 302 Stainless Steel?
most widely used stainless steel types
highly resistant to corrosion
very strong and hard
can be easily fabricated
192
What is Type 304 Stainless Steel?
the same as 302 except with improved weldability, and so has largely replaced type 302 for architectural uses
193
What is Type 301 Stainless Steel?
Similar to type 302 except wth improved work-hardening properties, which can result in very high tensile strength
194
What is Type 316 Stainless Steel?
Use for extremely corrosive environments (industrial plants and marine locations)
195
What is Type 430 Stainless Steel?
Less corrosion resistant and generally limited to interior applications
196
What are the 5 finishes for stainless steel?
No. 3 finish = intermediate, dull finish
No. 4 finish = general purpose finish that is dull. frequently used.
No. 6 finish = dull satin finish
No. 7 finish = highly reflective polished surface
No. 8 finish = the most reflective finish, used for mirrors and reflectors. seldom used for architectural applications
