What is the difference between coal tar and asphalt emulsions used for sealers? Which should I use?
A. Asphalt emulsions used to seal pavements are typically asphalt based. Coal tar, a derivative of the coal processing industry can also be used although asphalt emulsions are most commonly used. Coal tar based sealers can be somewhat more effective in areas where lighter fraction petroleum products may drip onto the surface of the HMA. An example of this would be where poorly maintained cars or equipment with oil leaks regularly drip their liquids onto the pavement in the same areas. Coal tar is more affective in repelling these drippings and preventing softening of the asphalt pavement. Typical application rates for sealers is about 0.05-0.1 gals./sq.yard. Latex modifiers and sand can also be added to enhance the sealer’s effectiveness and allow a thicker application rate. Concentrated sealing product labels will usually specify the amount of dilution with water necessary for different applications.
