Which waterproofing method uses a hot-applied asphalt mix that dries to form a durable waterproof layer?

• A. Sheet system waterproofing
• B. Liquid system waterproofing
• C. Bridge expansion joints
• D. Mastic asphalt system waterproofing

Answer: (D)

The method described is mastic asphalt system waterproofing. It relies on a molten asphalt mix that is heated and applied over the prepared substrate; as it cools, it hardens into a continuous, seamless, durable waterproof layer capable of withstanding traffic and movements on a bridge surface. This contrasts with sheet systems, which use pre-fabricated membranes laid in place, and with liquid systems, which form waterproofing by curing coatings rather than a hot-applied mix. Bridge expansion joints aren’t themselves a waterproofing layer but a structural feature where waterproofing is often applied nearby.