A2LA
American Association for Laboratory Accreditation

AAMA
American Architectural Manufacturers Association: US trade association that establishes voluntary standards for the window, door, and skylight industry.

abrasion
Wear or removal of the surface of a solid material as a result of relative movement of other solid bodies in contact with it

abrasion
Wear or removal of the surface of a solid material as a result of relative movement of other solid bodies in contact with it

abrasive media
Moderately to extremely hard materials, usually in a fine or very fine particulate form, used in abrasive blasting to remove surface contaminants or to grind and polish samples to the desired thickness or finish. Examples of moderately hard abrasive media are sand, iron shot, crushed iron slag, glass beads or ground nut shells. Examples of extremely hard abrasive media are industrial diamonds.

abrasion resistance
The ability of a construction element, such as a floor, pavement, roof or coating to resist degradation due to mechanical wear such as foot or wheel traffic and wind blown particles which tend to progressively remove materials from its surface.

absorbed water
Mechanically held water in a porous material (as concrete, soil mass, aggregates) and having physical properties not substantially different from ordinary water at the same temperature and pressure. See adsorbed water.

Absorptance
The ratio of radiant energy absorbed to total incident radiant energy.

absorption
1. The weight of water a solid (such as a brick unit) absorbs, when immersed in either cold or boiling water for a stated length of time. Expressed as a percentage of the weight of the dry unit. For masonry see ASTM C 67.
2. Process in which molecules are taken up by a liquid or solid and distributed throughout its body; compare with adsorption.

absorption field
Area through which septic tank effluent discharges (through leaching or seepage) into the surrounding ground. It comprises of a series of perforated pipes laid in shallow trenches backfilled with a predesigned arrangement of sand and gravel.

absorption rate
Absorption expressed as function of time.

accelerated corrosion test
A test method designed to simulate, in a short time span, the destructive action of corrosion under normal long-term service conditions.

accelerated weathering
A test designed to simulate the deteriorating effect of natural outdoor weathering, with controlled, intensified and accelerated processes.

accelerator
Substance used in small proportions to increase the speed of a chemical reaction. Accelerators are often used in the paint industry to speed up drying.

acid
1. Chemical substance that yields hydrogen ions (H+) when dissolved in water; this hydrogen that may be replaced by metals with the formation of salts. Compare with base.
2. A solution of pH less than 7.0 at 25 degrees C (pH=5.5-7 signifies mild acidity).

acid embrittlement
Form of hydrogen embrittlement that may be induced in some metals by acid treatment or other acid exposure.

acid-etch tube
A glass tube charged with dilute hydrofluoric acid. Used to measure inclination: after being left in a borehole for 20 to 30 min, the inclination will be indicated by the angle of etch line on the tube. May be fitted in a clinometer. This method is called "acid-dip survey".
Syn:acid-etch vial; culture tube; etch tube; sargent tube acid rain
Atmospheric precipitation with a pH between 3.6 to 5.7. Burning of fossil fuels is the major factor generating oxides of sulfur and nitrogen, which are converted into nitric and sulfuric acids when mixed with atmospheric water. See also atmospheric corrosion.

acrylic
1. Thermoplastic with reasonable optical clarity, plus good weather and shatter resistance. 2. One of the resins present in latex paints. It serves as bonding agent for the other ingredients. See Acrylic Latex.

acrylic latex
An aqueous dispersion of acrylic resins in latex paints.

Acrylic Resin (acrylic coating, acrylic plastic)
Group of clear, thermoplastic resin polymerized from various acrylic monomers (acrylic acid (C3H4O2) or methacrylic acid (C4H6O2), or a derivative of either, especially an ester, e.g., methyl methacrylate), either alone or in combination. One such acrylic resin, polymethyl acrylate, which is a tough rubbery material, is used in various industrial finishes, lacquers, and pressure sensitive adhesives. Others, such as Lucite, are used in flat or corrugated panels.

activation
The changing of a passive metal surface to a chemically active state. Contrast with passivation.

activator
1. The activation agent of metal surface. See activation.
2. The curing agent of a two component product such as a coating system or an adhesive.

active
State in which a metal tends to corrode; opposite of passive or noble.

active earth pressure
Horizontal push from earth on a retaining wall.

adhesion
The degree of attachment between two or more bodies during their service life, such as a: a paint film to the underlying material to which it is in contact (substrate) or b: the ability of a roofing membrane to remain attached to the substrate or to itself.

adsorbed water
Water held on surfaces of a material: in a soil or rock mass, this is water held by physico-chemical forces, having physical properties substantially different from absorbed water or chemically combined water, at the same temperature and pressure.

adsorption
Process of attraction (or attachment) to a surface. The surface retention of solid, liquid, or gas molecules, atoms, or ions on the surface of a substance (either solid or liquid).

admixture
Liquid or finely ground solid materials combined into a particular concrete, mortar or grout mix design in predetermined, minute, and very controlled quantities. The intended result is a major change in the behavior of the resulting product.

Aerogel
A microporous, transparent silicate foam used as a glazing cavity fill material, offering possible U-values below 0.10 BTU/(h-sq ft-°F) or 0.56 W/(sq m-°C).

age hardening
Process of hardening by aging; in metals usually occurs after rapid cooling or cold working. It can be generally favorable (for concrete, mortar) or unfavorable (for metals, elastomers, etc.).

aggregate/-g&t/ Function: noun
Date: 15th century

1 : any granular mineral material
2. a : Crushed stone, crushed slag, or water-worn gravel used for surfacing a built-up roof b : any of several inert materials, either hard (such as crushed rock, sand, gravel, and crushed slag) or semi-soft (such as rubber) used for mixing with a cementing materials to form concrete, mortar, grout, asphalt or plaster c : a clustered mass of individual soil particles varied in shape, ranging in size from a microscopic granule to a small crumb, and considered the basic structural unit of soil. Inert materials added to a mix in order to save on more expensive ingredients and impart special properties.
3: an aggregate rock
See ASTM C33 (aggregate for concrete), C144 (aggregate for masonry mortar)

aging
1. Change in the properties of certain metals and alloys that occurs at ambient (or somewhat elevated) temperatures after hot working or a heat treatment (quench aging in ferrous alloys, natural or artificial aging in ferrous and nonferrous alloys) or after a cold-working operation (strain aging). The change in properties does not involve a change in the chemical composition of the metal or alloy.

air barrier
Intentionally designed and constructed barrier meant to prevent both the exfiltration of indoor air to the outside and the infiltration of outdoor air into the building environment. This applies whether the air is humid or relatively dry. Air leakage will cause the deposition of moisture in both cavity and solid walls, as well as energy losses and rain infiltration.

air drying
Curing method of a film coating in which drying occurs by simple air exposure and without heat or the presence of a catalyst; the process of curing happens either by oxidation or bysolvent evaporation.

air entrapment
Intentional or accidental inclusion of air bubbles in materials such as concrete or liquid paint. Note: air bubbles present before curing tend to remain dispersed in the hardened material.

Air Impermeability
1. Airtightness
2. A major requirement of an air barrier is that it offer a high resistance to air flow. While absolute air impermeability may not be required, materials such as glass, sheet metal, gypsum board, cast-in-place concrete and a properly supported polyethylene sheet offer a much higher resistance to air flow than do more porous materials such as concrete blocks, fibre board sheathing, and expanded polystyrene insulation. A second major consideration is that individual panels be joined into an airtight assembly. The joints between gypsum boards can be taped quickly and effectively, sheet metal panels can be lapped with tape, precast panels can be sealed with rope and sealants, etc.

Air infiltration
The amount of air leaking in and out of a building through cracks in walls, windows and doors.

air leakage
Air flow in and out of a building, which occurs under two conditions: there must be an opening in the building envelope and there must be an air pressure difference across the wall at that location. The opening need not be straight or direct through the wall: it can follow a convoluted path inside the wall. As for the pressure difference, it can result from one or combination of three possible causes: wind, stack effect, and fan pressurization.

Air leakage can cause a number of problems: spalling masonry, ice build-up under soffits, frozen pipes, condensation in cavities, rain leaks, high energy costs, and indoor humidity problems. The seeds for many of these pitfalls are sown during the design phase, largely because of major confusion concerning the function of the air and vapour barriers.

Air leakage rating
A measure of the rate of infiltration around a window or skylight, or through a wall in the presence of a specific pressure difference. It is expressed in units of cubic feet per minute per square foot of window area (cfm/sq ft) or cubic feet per minute per foot of window perimeter length (cfm/ft). The lower an envelope component's air leakage rating, the better its airtightness.

AIRCRAFT LOADING APRON
A paved or unpaved surface for loading cargo aircraft; loading personnel for medical evacuation and transient aircraft operations; or providing an apron area for fueling aircraft, arming and disarming aircraft weapons, loading and unloading ammunition, special handling or decontamination of chemical, biological, radiological (CBR) warfare items, and for special security operations.

AIRCRAFT MAINTENANCE PARKING APRON
A paved or unpaved apron for parking fixed or rotary wing aircraft awaiting maintenance.

AIRCRAFT RUNWAY HOLDING APRON
A paved or unpaved surface providing an aircraft holding area accessible from a taxiway. It is located near the intersection of taxiways and ends of runways and is provided for pre-takeoff engine and instrument checks. For inventory purposes, only the prepared surface is included.

AIRFIELD PAVEMENTS: APRONS
Prepared surfaces, other than runways and taxiways, where aircraft are parked or moved about the airfield. They are designed to support specific types of aircraft and to meet operational requirements such as maintenance and loading activities.

airless spray
A type of spraying system in which paint is atomized by using high hydraulic pressure, rather than compressed air.

alclad
Composite material having an aluminum alloy core clad on one or both surfaces with a metallurgically bonded aluminum or aluminum alloy coating that is anodic to the core and thus electrochemically protects the core against corrosion.

alcohol
Group of solvents including ethanol, methanol, and isopropyl; they tend to have relatively high evaporation rates and fairly low solvent strength.

algae
Low form of plant (and plant-like) organisms containing chlorophyll, which lets them use energy from light to convert complex molecules into nutrients (photosynthesis).

Aliphatic Hydrocarbons
A class of organic solvents which are composed of open chains of carbon atoms. Aliphatics are relatively weak solvents. Mineral spirits and VM & P Naphtha are aliphatic solvents.

alkali
An aqueous substance which has a pH value of 7-14; a base or caustic material.

alkali metal
Any of the highly reactive metals (such as lithium, sodium, potassium, rubidium, cesium, and francium) found in the first column of the periodic table. They act as bases (form strongly alkaline hydroxides), hence the name.

Alkali-silica reaction (ASR)
Reaction of alkalis with aggregate with various forms of poorly crystalline reactive silica: opal, chert, flint and chalcedony and also tridymite, crystoblite and volcanic glasses. Aggregate containing such materials (e.g., some cherty gravels) may cause deterioration of concrete when present in amounts of 1% to 5%. Concrete made of these aggregates is characterized by the early onset of a relatively rapid expansion. Cracking of structures is often observed within 10 years of construction.

Alkali-silicate/silica reaction (ASSR)
Reaction of alkalis with strained quartz is thought to be one reactive component of aggregates causing this reaction. A wide variety of quartz-bearing rocks have been found to be reactive including graywackes, argillites, quartzwackes, quartzarenites, quartzites, hornfels, quartz biotite, gneiss, granite, phyllite, arkose and sandstone. This type of reaction is characterized by a delayed onset of expansion and cracking may not become evident for up to 20 years after construction.

alkaline
1. Having a pH value of between 7 and 14
2. Having properties of an alkali. (2) Having a pH greater than 7.

alkyd
Common term for oil based paints

alkyd resin
Modified form of resins prepared by combining alcohol and fatty acids. Widely used in general purpose coatings such as laquer paints, varnishes, and metal finishes.

alligatoring
Roofing or pavement defect characterized by randomized cracking of the surfacing bitumen, producing a pattern of cracks similar to an alligator's hide; these cracks may or may not extend through the whole thickness of the surfacing bitumen.

alloy
Substance composed of two or more elements, of which at least one is a metal. These elements are intimately united usually by being dissolved in each other when molten.

amorphous
non-crystalline, without long-range order; lacking organization or unity

aluminum roof coating: Fibered or unfibered cutback asphalt coating pigmented with microscopic aluminum flakes.

amine/&-'mEn, 'a-"mEn/
Materials often used as curing agents for epoxy coatings: any of a class of organic compounds derived from ammonia by replacement of hydrogen with one or more alkyl groups.  

anchor pattern
Substrate preparation: the surface profile obtained by abrasive treatments such as sand blasting or power tool cleaning; may also refer to the distance between peaks and valleys of the blast profile.

anchor

1. Piece or assemblage, used to attach building parts (e.g., support plates, ties, joists, trusses, etc.) to concrete, masonry or metals.
2. Mechanical (expansion anchor) or chemical (often a two part resin with or without aggregate) assembly used to connect masonry or other veneer to back-up walls. See ASTM E488

Annealed glass
Standard sheet of plate glass.

annealing
Generic term used to denote a controlled heat treatment process, followed by cooling performed on material in the solid state. It is used to remove stresses, to induce softness and to alter the ductility and toughness of metals, glass, or other materials by allowing them to recrystallize. The temperature of the operation and the rate of cooling will depend upon the metal and the purpose of the annealing.

anode
The positive terminal of an electrical source. In a corrosion cell, the anode is the electrode of an electrochemical cell at which oxidation occurs

ANSI
American National Standards Institute.

ANTENNA
A metallic aerial for sending and receiving electromagnetic waves. A transmitting antenna converts electrical signals from a transmitter into an electromagnetic wave which it then emanates. A receiving antenna intercepts an electromagnetic wave and converts it back into electrical signals that can be decoded by a receiver. Central television, pole and wire, and switching station antennas, as well as satellite dishes, are also included within this category code.

application rate
The quantity (mass, volume or thickness) of coating material applied per unit area.

AR 420-70
U. S. Army Regulation 420-70, "Facilities Management-Buildings and Structures"

area divider
A raised, double wood member attached to a properly flashed wood base plate that is anchored to the roof deck. It is used to relieve the stresses of thermal expansion and contraction in a roof mebrane where no expansion joints have been provided.

Argon
Inert, nontoxic gas used in insulating windows to reduce heat transfer.

ARMA
American Roofing Manufacturers Association

Aromatic Hydrocarbons
A class of relatively strong organic solvents which contain an unsaturated ring of carbon atoms. Examples are benzene, toluene and xylene.

asbestos/as-'bes-t&s, az-/
Any of several naturally occuring, fibrous, impure silicate materials; have been implicated as causes of certain cancers, and that have been used in the past as fireproofing and insulating materials

ash·lar/'ash-l&r/
Masonry composed of (mostly) rectangular units made of cut stone, cultured stone, burned clay or shale, and generally larger in size than regular brick. The ashlar units are properly bonded, having sawed, dressed or squared beds, and joints laid in mortar. Often the unit size varies to provide a random pattern, random ashlar. Also used as ash·lar masonry

ASHRAE
American Society of Heating, Refrigerating and Air-Conditioning Engineers

asphalt
A dark brown to black cementitious material in which the predominating constituents are bitumens, which may occur naturally or are obtained in petroleum refining. It is used as a waterproofing agent, sealant or pavement.

asphalt felt
A mat of organic or inorganic fibers, impregnated with asphalt or coal tar pitch, or impregnated and coated with asphalt.

asphalt mastic
Mixture of asphaltic material and graded mineral aggregate that can be poured when heated, but requires mechanical manipulation to apply when cool.

ASTM
American Society for Testing and Materials.

aw·ning
/ 'o-ni[ng], 'ä-ni[ng]/ Function: noun
Etymology: origin unknown
Date: 17th century
Rooflike cover made of fabric, concrete, metal, plastics, etc. which extends over or in front of a place (as over the deck or in front of a door or window) as a shelter

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