Which material is not part of the standard mortar composition?

Which material is not part of the standard mortar composition?

• A. Cement
• B. Gypsum
• C. Lime
• D. Sand

Answer: (B)

Mortar for masonry relies on a binder, a plasticizing or lime component, and an aggregate. In modern practice, cement serves as the primary binder, lime is often included to improve workability and bonding, and sand provides the bulk and strength. Gypsum, on the other hand, is the binder used in gypsum plaster, not in standard cementitious mortar, because its setting behavior and durability in masonry joints don’t align with typical mortar performance. That’s why gypsum does not belong in the standard mortar mix.

Mortar for masonry relies on a binder, a plasticizing or lime component, and an aggregate. In modern practice, cement serves as the primary binder, lime is often included to improve workability and bonding, and sand provides the bulk and strength. Gypsum, on the other hand, is the binder used in gypsum plaster, not in standard cementitious mortar, because its setting behavior and durability in masonry joints don’t align with typical mortar performance. That’s why gypsum does not belong in the standard mortar mix.