Bitumen is a low-grade of crude oil which is composed of complex, heavy hydrocarbons. In order to get a higher grade and quality of this product it is refined several times. Bitumen over the years has been used for a variety of purposes due to its waterproofing and adhesive features. It is also used for emulsion and coating purposes.
These are slowly gaining popularity as they not only provide a low-cost solution for the construction wall/gypsum, but also come with the added advantage of having a more decorative design to the product. They seem to have acquired a niche market.