Which type of glass block is specified in the material?

• A. Glass block
• B. Hollow glass blocks
• C. Concrete brick
• D. Hardened clay

Answer: (B)

Glass blocks are specified by their construction, and hollow versions are chosen when you need a light-diffusing, lighter, and easier-to-install block with good thermal and acoustic performance. Hollow glass blocks have air cavities that reduce weight and improve insulation while still allowing light to pass through. If the material calls for a glass block and explicitly uses hollow glass blocks, that indicates the intended type for the wall or partition. Solid glass blocks exist, but they are heavier and more expensive and aren’t what’s described here. The other options—concrete brick and hardened clay—are not glass blocks at all, so they wouldn’t be specified when the material calls for a glass block.