Which of the following is not a bitumen used for built-up membrane systems (BUR)?

• A. Coal-tar system
• B. Asphalt
• C. Coal tar pitch
• D. Modified bitumen

Answer: (A)

Built-up membrane systems rely on bitumen as the waterproofing binder in their plies. Asphalt-based bitumen, coal tar pitch, and modified bitumen are all used as bitumen options in BUR construction, each contributing to the waterproofing layer. A coal-tar system, on the other hand, uses coal tar as the primary waterproofing material rather than bitumen. Because BUR construction centers on bitumen-based materials, a coal-tar system does not fit as a bitumen used for BUR. That’s why the coal-tar system is the correct choice for “not a bitumen used for BUR.”