Which mortar type may be used to lay glass block?

Which mortar type may be used to lay glass block?

• A. type K
• B. type O
• C. type M
• D. type S

Answer: (D)

Mortar for glass block needs a balance of strength, workability, and durability to hold the blocks securely while tolerating slight movement and moisture. Type S mortar provides that balance: it has higher bond strength than the weaker mixes, yet remains workable enough to pack into narrow joints and finish neatly around glass blocks. This makes it well suited for masonry work that involves blocks and the stresses of moisture and temperature changes. The other options don’t fit as well. A very weak mix isn’t capable of reliably holding the blocks in place. A patching or lime-based putty is intended for repairs rather than new construction and jointing of glass block. A very high-strength mix can be stiffer and more prone to shrinkage, potentially stressing the blocks and cracking joints. So the best choice for laying glass block is Type S mortar.

Mortar for glass block needs a balance of strength, workability, and durability to hold the blocks securely while tolerating slight movement and moisture. Type S mortar provides that balance: it has higher bond strength than the weaker mixes, yet remains workable enough to pack into narrow joints and finish neatly around glass blocks. This makes it well suited for masonry work that involves blocks and the stresses of moisture and temperature changes.

The other options don’t fit as well. A very weak mix isn’t capable of reliably holding the blocks in place. A patching or lime-based putty is intended for repairs rather than new construction and jointing of glass block. A very high-strength mix can be stiffer and more prone to shrinkage, potentially stressing the blocks and cracking joints. So the best choice for laying glass block is Type S mortar.