Air-blowing:
The manufacturing process used to make oxidized roofing asphalts in
which air is blown through an asphalt flux. An exothermic oxidation
reaction occurs, yielding an asphalt that is harder, more viscous, less
volatile, and less temperature-susceptible than the asphalt flux used
as the feedstock to the process.
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Asphalt:
(CAS number 8052–42–4)
The product of the nondestructive distillation of crude oil in petroleum
refining; it is a dark brown to black, cement-like semisolid or solid.
Depending on the crude oil used as a feed-stock, the distillation residuum
may be further processed, typically by air-blowing (sometimes with a
catalyst) or solvent precipitation to meet performance specifications
for individual applications [AI 1990b]. Asphalt is a mixture of paraffinic
and aromatic hydrocarbons and heterocyclic compounds containing sulfur,
nitrogen, and oxygen [Sax and Lewis 1987].
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Asphalt,
cutback:
An asphalt liquefied by the addition of diluents (typically petroleum
solvents) [AI 1990b; Roberts et al. 1996; Speight 1992].
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Asphalt
flux:
The residuum of atmospheric and vacuum distillation processes used by
petroleum refineries and independent asphalt manufacturers; used in
the manufacture of some asphalt roofing materials (e.g., saturant asphalts,
some modified bitumen products); also used as a feedstock in the air-blowing
process used to make oxidized roofing asphalt.
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Asphalt
fumes:
The cloud of small particles created by condensation from the gaseous
state after volatilization of asphalt [NIOSH 1977].
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Asphalt,
oxidized (blown or air-refined) (CAS number 64742–93–4):
Asphalt treated by blowing air through it at elevated temperatures to
produce physical properties required for the industrial use of the final
product. Oxidized asphalts are used in roofing operations, pipe coating,
undersealing for Portland cement concrete pavements, hydraulic applications,
membrane envelopes, some paving-grade mixes [AI 1990b], and the manufacture
of paints [Speight 1992].
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Blowing
still:
A closed-process vessel fitted at its base with a sparger and used in
the air- blowing process to make many types of roofing asphalt.
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Built-up
roofing (BUR):
A system of asphalt-impregnated felt plies sealed and surfaced with
hot mopping-grade asphalt; primarily used in low-slope commercial roofing.
The felt plies can be organic (e.g., cellulose), fiberglass screen or
mat, or polyester fabric.
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Coating
asphalt:
An air-blown or oxidized asphalt used to manufacture roofing materials
used in a variety of roofing systems such as asphalt shingles, polymer-modified
bitumen roofing, reinforcing and underlayment felts, and roll roofing
products.
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Modified
bitumen:
A roofing system based on membranes manufactured by impregnating or
coating one or more fabric plies with a straight-run or oxidized asphalt
modified using a polymer, usually atactic polypropylene (APP) or styrene-butadiene-styrene
(SBS). Modified bitumen sys-tems may be torch-applied or installed by
adhesion in hot asphalt or a cold-applied, solvent-based asphalt adhesive
(cutback asphalt). Modified bitumen systems are used on low-slope (primarily
commercial or industrial) roofs.
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Mopping-grade
asphalt:
An oxidized asphalt used principally in the construction of BUR and
some modified bitumen systems; mopping-grade asphalts are produced in
four grades (Types I through IV) according to the steepness of the roof.
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Saturant
asphalt:
A nonoxidized or oxidized asphalt, typically an AC–10 or AC–20
grade material, used to manufacture saturated organic felt plies used
in the construction of BUR systems, organic felt shingles, and other
roofing materials such as roll roofing.
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Straight-run
asphalt:
The residuum of atmospheric and vacuum distillation processes used in
petroleum refineries and by independent asphalt manufacturers. This
asphalt is used in the manufacture of some asphalt roofing materials
(e.g., saturant asphalts, some modified bitumen products); it is also
used as a feedstock in the air-blowing process used to make oxidized
roofing asphalt.
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