Midterm! Flashcards
Commit this nonsense to memory.
1
Q
Entropy
A
The Second Law of Thermodynamics (Energy spontaneously tends to flow only from being concentrated in one place to becoming diffused or dispersed & spread out). A measure of the amount of energy which is unavailable to do work.
2
Q
Element
A
Substance that cannot be decomposed into simpler substances.
3
Q
Compound
A
Substance formed by the combination of elements fixed in proportions.
4
Q
Atom
A
Smallest part of an element that can ever exist consisting of a dense nucleus of protons and neutrons surrounding by moving electrons.
5
Q
Molecule
A
The simplest structural unit that displays the characteristic physical and chemical properties of a compound.
6
Q
Ion
A
Atom or group of atoms that has lost one or more electrons making it positively charged (cation) or gained one or more electrons making it negatively charged (anion).
7
Q
Chemical Bond
A
Strong force of attraction based on transfer or sharing of electrons that holds atoms together in a molecule.
8
Q
Chemical Reaction
A
Change in which one or more chemical elements or compounds form new compounds.
9
Q
Durability and performance of a material determined by what factors?
A
Density Porosity Permeability Absorption Adsorption Strength Thermal Properties Acoustic Properties Frost Resistance Soluble Salt Content Chemical Resistance Fire Resistance Susceptibility to Deformation Susceptibility to Deterioration and Decay Natural and Production Defects Appearance
10
Q
Cellulose
A
Wood
Crystalline polysaccharide consisting of a long unbranched chain structure of glucose units; responsible for providing rigidity of the cell wall; represents approx. 45-60% of the dry weight of wood.
11
Q
Hemicellulose
A
Wood
Semi-crystalline polysaccharide consisting of a shorter chain structure; represents approx. 10-25% of the dry weight of wood.
12
Q
Lignin
A
Wood
A complex amorphous organic polymer deposited within the cellulose of plant cell walls; lignification makes the walls woody and therefore rigid; represents approx. 20-35% of the dry weight of wood; greater proportion present in softwoods than hardwoods.
13
Q
Igneous Rocks
A
Formed by the solidification of molten rock material.Coarse or fine grained. Granite, basalt, quartz, feldspars, mica
14
Q
Metamorphic Rocks
A
Formed through the alteration of igneous and sedimentary rocks by the action of heat and pressure.Slate, schist, gneiss
15
Q
Sedimentary Rocks
A
Formed by the accumulation of rock waste at the Earth’s surface.Coarse, medium, or fine grainedClassified according to origin:- Mechanical- Chemical- Organic Limestone, sandstone
16
Q
Binder
A
Material used to form the cementing matrix in mortars, renders and plasters, and which typically is derived from lime, gypsum, or artificial cements. Mixed with sands and aggregates to provide workable product.
17
Q
Concrete
A
A mix of binder with sands and other aggregates to form an amorphous material capable of use.
18
Q
Ferrous Metals
A
Cast and wrought iron.Composed principally of iron with varying amounts of carbon and other elements. Wrought iron strong in tension.Cast iron is brittle in nature; used in compression for columns.
19
Q
Non-ferrous Metals
A
Sheet roof coverings, flashings, weatherings, plumbing.Lead, copper, zinc, aluminum.
20
Q
Bituminous Products
A
Asphalt and bitumen; amorphous (non-crystalline).Typically resistant to the passage of water and water vapor. Liable to flow or creep under mechanical stress and soften in response to increase in temperature.
21
Q
Saturation
A
Maximum water vapor content in the air
22
Q
Humidity Ratio
A
The ratio of the water vapor mass to the dry air mass. [units: lb or kg, or as grains of water vapor] Also called Absolute Humidity or Moisture Content.
23
Q
Relative Humidity
A
A measure of how much water vapor air is holding relative to how much water vapor it could hold at that temperature and pressure. The ratio of vapor pressure of water (Pv) (partial pressure at saturation) to the actual partial pressure of water vapor(PH20). Relative Humidity = PH2O / Pv x 100%
24
Q
Dry Bulb Temperature
A
The temperature of the air as measured with any common thermometer.
25
Wet Bulb Temperature
Temperature taken with a sling psychrometer
The sling psychrometer has two thermometers, one of which is covered with a wick that is saturated with water. As the psychrometer swings through the air, water is evaporated from the wick, cooling the thermometer. The thermometer with the wick eventually reaches a stable temperature, which is referred to as the wet bulb temperature. The drier the air, the greater the difference between the wet and dry bulb temperatures will be.
26
Dry Bulb Temperature
The temperature of the air as measured with any common thermometer.
27
Dew Point Temperature
A temperature at which the water vapor begins to condense. (also: temp at which air becomes completely saturated)
28
Humid Volume
The total volume of the humid air per unit mass of bone dry air. This quantity may be expressed as either cubic feet per pound of dry air, or cubic meters per kilogram of dry air.
29
Enthalpy
The enthalpy of humid air is a measure of its heat content. When the air is less than 100% relative humidity, its enthalpy will be lower than if it were saturated. Energy/Mass of Dry Air = Btu/lb Dry Air
30
Unconsolidated Deposits
Material derived from the disintegration of consolidated rocks. The material consists in different types of unconsolidated deposits of particles of rocks or minerals ranging in size from fractions of a millimeter (clay size) to several meters (boulders). Those important in ground-water hydrology include,
in order of increasing grain size, clay, silt, sand, and gravel. also includes fragments of shells of marine organisms.
31
Consolidated Rocks
These consist of mineral particles of different sizes and shapes that have been welded by heat and pressure or by chemical reactions into a solid mass. Commonly referred to as bedrock. They include sedimentary rocks that were originally unconsolidated and igneous rocks formed from a molten state. Those important in ground-water hydrology include limestone, dolomite, shale, siltstone, sandstone, and conglomerate . Igneous rocks include granite and basalt.
32
Primary Openings
Voids formed at the same time as the rock. The pores in sand and gravel and in other unconsolidated deposits are primary openings. Also lava tubes and other openings in basalt.
33
Secondary Openings
Voids formed after the rock was formed. These include fractures in granite and in consolidated sedimentary rocks are secondary openings. Voids in limestone, which are formed as ground water slowly dissolves the rock, are an especially important type of secondary opening.
34
Ground Water Hydrology
A subdivision of the science of hydrology. Deals with the occurrence, movement, and quality of water beneath the Earth's surface.
35
Semi-Consolidated Rocks
Rocks in which openings include both pores and fractures--both primary and secondary openings.
36
Unsaturated Zone
The zone which occurs immediately below the land and contains both water and air. This zone can be divided into three parts: the soil zone, the intermediate zone, and the upper part of the capillary fringe.
37
Saturated Zone
Almost always immediately under the unsaturated zone and where all interconnected openings are full of water.
38
Capillary Fringe
The subzone between the unsaturated and saturated zones. Results from the attraction between water and rocks.
39
Water Table
The level in the saturated zone at which hydraulic pressure is equal to atmospheric pressure and is represented by the ater level in unused wells.
40
Specific Yield
Water in storage in the ground that will drain under the influence of gravity. Tells how much water is available for man's use.
41
Specific Retention
The part that is retained as a film on rock surfaces and in very small openings. Tells how much water remains in the rock after it is drained by gravity.
42
Watterlogged
Where the water table is at a shallow depth, the land may become "waterlogged" during wet weather and unsuitable for residential and many other uses
43
Latent Energy
A significant change in energy content that must occur before moisture changes state
44
Adsorption
The process whereby many surfaces in contact with water vapor molecules have the tendency to capture and hold water molecules because of the polar nature of the water molecule. summary: liquid water is ABsorbed into capillary pores, and significant amounts of water vapor can be ADsorbed to the surface of pore walls.
45
Hydrophobic
Materials that repel water
46
Hydrophilic
Materials that have the tendency to capture and hold water molecules. Most building materials are this way due to being porous and having very large internal surface areas.
47
Hygroscopic
As water-vapor molecules in the air adsorb to the internal surfaces (the pore walls) of these materials, the water content increases significantly. (Desiccants
are a special type of hygroscopic
material. They can absorb a very large
amount of moisture, typically several
times their dry weight at high relative humidities.)
48
Utility
Qualities of a building that make it potentially productive.
49
Adaptability
Ease with which a new use may be introduced into a building.
50
Dimensional and Spatial Factors that Influence a Building's Utility
Site relationship, geometry, spatial character, spatial organization, vulnerabilities, limitations, liabilities
51
Capacity Factors - Utility
Structure, robustness & resilience, energy efficiency, occupant health, system infrastructure, external services, regulatory factors
52
Heritage Building Reinvestment Model
Helps to organize components of a building, and determine how much money to set aside to properly maintain a building and accumulate funds.
53
Aspects to consider when understanding a building's materials
Origin and source, technological context, physical variability, material functions, constructability, properties
54
Soil Classification
4 basic soil types based on particle size:
- Gravel, sand, silt, clay
Further classified by gradation:
- Well-graded, uniform, gap graded
55
Gravels
Pervious, easy to compact, affected little by moisture or frost, room to expand and easy drainage
56
Sands
Less pervious than gravel, less stable when subjected to moisture, silt-like in properties in their finer gradations
57
Silts
Unstable when saturated and unconfined, low plasticity, tends to be dilatant (viscosity increases with the rate of shear strain) (like a viscous fluid when saturated "thick slurry"), a "problem soil" that slowly consolidates w/ time
58
Clays
Cohesive when wet, deforms easily, high plasticity, changes volume with changes in moisture content, change in MC results in differential settlement, if compressed, forms hard masses when dry
59
Soil Density
Affects porosity, permeability, particle mobility, and overall stability.
Related to soil capacity, to resist vertical loads.
Affects lateral loads that act on a foundation wall.
60
If soil is placed as infill, in order to achieve uniform density, the soil must:
Be placed and compacted in layers, and have optimum soil moisture content
61
Capillary Fringe
NEVER FORGET THIS EXISTS! This allows water to be drawn up in the soil.
62
Key parameters that characterize climate
Atmospheric composition (dry air & moisture vapor), thermodynamic state (temp & pressure), thermal energy input (solar radiation), moisture inputs (rainfall & snow), convection inputs (wind)
63
Mechanisms of air and moisture transport
Diffusion, capillary flow, forced convection, natural convection, liquid flow under gravity
64
Surface Tension
This is a significant factor in capillary flow, wetting, and drying.
It is caused by cohesive attraction of liquid molecules.
It must be overcome for evaporation.
Strong ST provides the force for capillary flow in a material - Low ST speeds wetting of a solid source.
65
Thermal energy flows from a hotter to a cooler by
Conduction, free or natural convection, forced convection, radiation, or as a transport due to a mixing of hot and cooler masses
66
Thermal Inertia
The capacity of a building to store thermal energy in its materials.
67
Moisture Buffering
The capacity of a building to store moisture in its materials.
68
Rising Damp
Refers to the general class of vertical water migration through masonry.
The necessary and sufficient factors for rising damp to occur:
- Porous, permeable masonry
- Continuous supply of bulk water at or near the base of a wall
- A vertically continuous network of water-transporting capillaries
69
Incipient Period
Deterioration has begun despite the apparent absence of damage; buildings begin to deteriorate immediately
70
Half-life of a building system
The end of effective life; the point at which the functional aspect of the system fails
71
Shortwave Radiation
Solar radiation
72
Long-wave Radiation
Radiation from terrestrial objects
73
Strain
The deformation per unit of the original dimension.
74
Modulus of Elasticity
The constant of proportionality--the ratio of stress under load to the accompanying strain--represents the inherent ability of the material to resist elastic deformation.
75
Penetrating Damp
Movement of moisture absorbed into a porous material is dependent on the severity of the conditions of exposure, length of time it is subjected to these conditions, and internal port structure of the material
76
Interstitial Condensation
Where the dew point temperature is reached within the thickness of the construction and condensation forms at that point
77
Stress Gradients
These exist when the value or magnitude of internal stress is not uniform across the cross-section of the sample
78
Toughness
The inherent resistance to crack formation depending on the material
79
Strain-limited Cracks
The expanding material is limited by the degree of thermal shift or hygroscopic expansion; common in masonry walls
80
Arrested Cracks
Not strain-limited; will continue to progress until arrested
81
Stable Cracks
If not progressing, then there is stress equilibrium
82
Elastic Materials
A material will deform under load and the material will return to its original shape when the load is removed
83
Brittleness
A measure of the fracture or cracking behavior, which is characterized as being rapidly accelerating
84
Plastic Behavior
Materials may deform predictably enough under load, but they do not return to their original shape or position when the load is removed; lack of recovery is essence of plastic behavior
85
Creep
Manifests by irreversibly, long-term deformation of structurally adequate members under constant load; predictable, easily solvable.
A member deformed by creep will rebound some elastic portion of the deformed shape; but after all load is removed, there will be a residual deformation
86
Moisture Flow in Buildings
```
PHASE
SOURCE
TRANSPORT
WETTING
STORAGE
DRYING
TRANSPORT
PHASE
SINK
```
87
Service Life
actual period of time during which the building & components perform without unforeseen costs or disruption for maintenance & repair ("Predicted Service Life" = based on previous experience or recorded performance)
88
Cohesion vs. Non-Cohesion
Pure sand is COHESIONLESS when dry (hour glass) \\ pure clay is COHESIVE when wet & after drying (pottery)
\\adding a small amount of clay to sand results in cohesive soil mix
89
Moisture storage regimes in hygroscopic porous material
top to bottom:
E. SUPERSATURATION: pores filled by pressure/vacuum (+/-)
[free capillary water]
D. CAPILLARY SUCTION: free water in pores, filling pores by capillary flow
[adsorbed water: hydroscopic regime]
C. SORPTION: adsorbed molecules in interconnected layers, capillary condensation on bridging between layers of liquid across a pore
B. SORPTION: adsorbed molecules in multiple layers on pore surface
A. SORPTION: adsorbed molecules in single layers on the pore surface
90
Diffusion
random molecular movement of a liquid or gas due to differences in temperature or convection
91
Capillary flow
movement of a liquid due to surface tension at contact between liquid & material; temperature dependent
92
Forces
an influence causing change in shape or movement of a body/ defined by: magnitude, direction, and point of application (a vector---> is the symbolic representation of a force)
93
Collinear Forces
Forces acting along the same line & direction; are additive ------>------->
94
Concurrent Forces
Forces intersecting at a single point; can be resolved into a single force, usually by vector addition
95
Non-concurrent Forces
Forces that act around a single point & result in rotation
96
Static Equilibrium
A body is in SE if the sum of all linear & rotational forces equals zero
97
Stress
Force (F) per unit (A), usually measured in lbs / sq. inch
98
Compression
Stress acting to shorten an object
| -->[]<--
99
Tension
Stress acting to lengthen an object
100
Shear
Stress acting parallel to a surface deforms angles of an object, or causes 2 objects to divide (think stack of cards)
101
Mechanical Deterioration
Material change due to stresses & strains from external load(s) or displacement(s); examples: rupture, full or partial fracture, crack formation, embrittlement or loss of elasticity/fatigue, plastic deformation, dislocation or displacement, abrasion, erosion, non-reactive weathering
102
Hygrothermal Mechanisms of Deterioration
Material change due to stresses or strains from volumetric or dimensional change as a result of thermal energy or moisture content change; examples: rupture, embrittlement, plastic deformation, dislocation
103
Hygrothermal Mechanisms of Deterioration enabling factors
temperature cycles, extremes, or one-time events; moisture content cycles, extremes, one-time events; constraint (internal or external to the object)
104
Constraint
A necessary factor for hygrothermal deterioration. External constraints or fixity may take different forms: fixed@ one end relative to the other, @both ends equally, @one or two ends and laterally
105
Anisotropic
properties differ by direction.
106
Anisotropic aspect of Hygrothermal dimensional change in wood
Results in deformations according to grain structure. Bow=Plane / Crook=Edge / Twist=Length / Cup, Diamond, Oval=Face
107
Biological Deterioration
Consumption or transformation by a living organism. Perhaps displacement; Affects organic and occasionally inorganic materials; Includes: micro-organisms (bacteria, fungi, mold), insect infestation, large pests, vermin and critters, birds & excrement, flora
108
Biological Deterioration depends on
Typically depends on presence of: moisture, nutrients, oxygen (but not always),activation energy such as heat, time to germinate, light (sometimes)
109
Biological Deterioration of Wood
Fungal activity: Dependent on fungal species & wood species, May occur in heartwood or sapwood, May consume lignin (brown rot) resulting in cracked collapsed cells, often in softwood, Appears crumbly when dry, May consume both cellulose and lignin (white rot) resulting in spongy cells, often in hardwood, Some fungi are water conducting, increasing moisture content of the surrounding wood
Bacteria: Not generally a concern, Can make wood more absorptive increasing other risks
110
Electro-Chemical Deterioration
Material change due to chemical reaction; Examples:oxidation of metals, chemical change of organic materials, galvanic corrosion between metals, reaction to soluble salts or air pollution particulates
111
Electro-Chemical Deterioration depends on
Typically depends on presence of: chemically reactive materials (inorganic & organic), moisture and/or oxygen, activation energy (heat, light, etc)
112
The Corrosion Process
Ions are involved & require a medium for transport
Oxygen is involved & a source is required
Base metal must be able to release electrons
A new material is formed & may: inhibit or accelerate the process
Activation energy or a “driving force” is required - 10 °C (18 °F) increase can double corrosion rate
113
Corrosion Types
* Uniform: evenly distributed
* Localized: specific to one are or exposure
* Pitting: associated with protective coating failure
* Selective: specific to a component or phase in an alloy
* Crevice: in tight spaces wetted by capillary wicking or surface tension
* ISCG: intergranular stress corrosion cracking formed at grain boundaries of stainless steel under stress w. chlorides
* Erosion: surface loss exposes fresh substrate for corrosion attack
* Galvanic: dissimilar metals in electrolytic contact
* Atmospheric: condensation and RH
* Corrosive agents/chemicals: solutions, soluble particulates, microbial secretions, bacteria, organic decomposition, salts from treatments
114
Galvanic Corrosion
Electron exchange between dissimilar metals in electrically conductive contact; Requires - one metal more that freely yields electrons relative to the other - electrical continuity between the metals - a path for ion/electron exchange, such as an electrolyte
115
Corrosion Opportunities in Metals in Buildings
* Primary & secondary structural members
* Sheet cladding on roofing & walls
* Flashing
* Glazing systems, windows & doors
* Ornament
* Functional or decorative metal embedments in porous/permeable materials or assemblies
* Reinforcement steel (rebar) in concrete or masonry*
* Fasteners in organic and inorganic materials
* Electrical devices
* Piping systems & pumps
116
Necessary & Sufficient Conditions
Necessary conditions: Every mechanism has a specific set of requirements or conditions that must be met in order for the mechanism to exist.
Sufficient conditions: those circumstances that, if present, will result in the mechanism.
When all nec & suf conditions are present, the mechanism will activate and persist until a nec condition is eliminated.
