S: http://callape.com/issue/may-2014/article/understanding-the-differences-between-asphalt-and-refined-coal-tar (last access: 7 February 2016); http://www.newworldencyclopedia.org/entry/Tar (last access: 7 February 2016).
N: 1. tar (n.1): a viscous liquid, Old English teoru, teru “tar, bitumen, resin, gum,” literally “the pitch of (certain kinds of) trees,” from Proto-Germanic *terwo- (cognates: Old Norse tjara, Old Frisian tera, Middle Dutch tar, Dutch teer, German Teer), probably a derivation of *trewo-, from PIE *derw-, variant of root *deru-, *dreu- in its sense “wood, tree” (see tree (n.)).
2. A viscous, adhesive material produced by the pyrolysis of coal, lignite, wood, etc.
3. tar: term standardized by ISO.
4. Unless otherwise stated, it is assumed that the origin is coal or similar material. It is never from petroleum origin.
5. coal tar, principal liquid product resulting from the carbonization of coal, i.e., the heating of coal in the absence of air, at temperatures ranging from about 900° to 1,200° C (1,650° to 2,200° F). Many commercially important compounds are derived from coal tar.
6. Low-temperature tars result when coal, peat, lignite, or wood are carbonized at temperatures not exceeding 700° C (1,300° F). Tar acids, phenolic compounds that react with caustic soda to form water-soluble salts, are extracted from coal tar after it has been distilled.
7. What is the difference between the tar road vs the concrete road? Which is long lasting?
Concrete Road is done by taking Cement as binder material where as tar road is done by taking bitumen as binder i.e WBM Road.
Concrete is Rigid pavement ,cost of construction is high but maintance cost is low with high flexural strength.
Tar road is flexible road with less cost of construction but maintance cost is high compare to concrete road,load transfer is done grain to grain.
Design period for Concrete is more then Tar road.
8. Cultural Interrelation: We can mention the book Gargling With Tar (2010) written by Jachim Topol.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=tar&searchmode=none (last access: 5 September 2014). 2, 3 & 4 TERMIUM PLUS (last access: 5 September 2014). 5 & 6. EncBrit – http://www.britannica.com/science/coal-tar (last access: 5 September 2014). 7. https://www.quora.com/What-is-the-difference-between-the-tar-road-vs-the-concrete-road-Which-is-long-lasting (last access: 7 February 2016). 8. http://www.goodreads.com/book/show/21118517-gargling-with-tar (last access: 7 February 2016).