Handbook of Solvents - George Wypych - ChemTech - Ventech!

14.3 Asphalt compounding 855
This will aid the stripping action of the proposed stripping solvent, benzyl alcohol. VOC
have already been reduced in several components: bonding primer (from 1030 to 850 g/l),
undercoats (from 670 to 350), top coats (from 700-900 to 250-800), clear coats (from
700-800 to 250-520), surface cleaners (from 850 to 250) as well as other materials. 3
REFERENCES
1 Profile of the Aerospace Industry. EPA Office of Compliance Sector Notebook Project. US Environmental
Protection Agency. November 1998.
2 R W Blackford, Surface Coatings International, 80, No.12, 564-7 (1997).
3 R Blackford, Polym. Paint Colour J., 186, No.4377, 22-4 (1996).
14.3 ASPHALT COMPOUNDING
George Wypych
ChemTec Laboratories, Inc., Toronto, Canada
Numerous construction products are formulated from asphalt and coal tar for such applications
as driveway sealers, cutback asphalts, flashing cements, concrete primers, concrete
cold mixes, roof cements, expansion joint fillers, patch liquids, waterproofing
liquid-applied membranes, and pipeline coatings. All these products are likely to contain
solvents.
The simplest formulations are mixtures of asphalt and (usually) mineral spirits used
for sealing , priming, and coating of concrete. These are usually very low performance products
which are used in large quantities because of their low price. They release about 40% of
their weight to atmosphere during and after application. Since they do not perform well they
have to be re-applied at frequent intervals. Driveway sealer is an example of a product
which is used every spring, in spite of the fact that, in addition to the pollution it causes, it
also produces a gradual degradation and cracking of the driveway. The only solution for
elimination of this unnecessary pollution seems to be banning the product by regulation.
Some of these products can be replaced by asphalt emulsions which contain water in place
of organic solvents.
Several products are used for patching and joint filling purposes. These materials
(flashing cement, roof cement, patch liquid, and expansion joint filler) also use solvents to
regulate viscosity. The solvents are usually mineral spirits, fuel oil, or polycyclic aromatic
hydrocarbons. In addition to the base components, inexpensive fillers such as calcium carbonate
or limestone but also still asbestos are added. These products harden on evaporation
of the solvent and fill the joints, adhere to surfaces, and provide some waterproofing. These
are again, low technology materials, traditionally used because of their very low cost. Most
of these products can be replaced by modern sealants which will result in higher initial cost
but longer service.
The most technologically advanced products are used for waterproofing and pipeline
coatings. These products are also based on dispersion of asphalt in the above mentioned solvents
but reinforced with addition of polymer. The addition of polymer modifies the plastic
behavior of asphalt and renders it elastomeric. Additional solvents are usually added to improve
the solubility of polymeric components. Reactive polyurethanes are the most frequently
used modifiers for waterproofing liquid membranes. Toluene and xylene are the