Understanding the Difference Between Repair Mortar and Masonry Mortar

Today, we’re going to discuss the difference between repair mortar and masonry mortar. While both are types of mortar, they serve distinct purposes and have different properties.

What is Mortar?

To understand the differences, we first need to define what mortar is. According to the American Concrete Institute (ACI), mortar is a mixture of Portland cement, a fine aggregate (such as sand), and water. Admixtures can also be added to enhance certain properties, but the essential ingredients remain sand and cement.

Masonry Mortar

Masonry mortar is specifically designed for laying and binding masonry units like bricks, blocks, and stones. It typically includes:

• Cement with Lime: The addition of lime improves workability and water retention.
• Mason Sand: This is finer than concrete sand, providing a smoother texture suitable for masonry work.

Masonry mortar is formulated to meet the ASTM C270 standard, ensuring it has the right properties for constructing walls and other masonry structures.

Repair Mortar

Repair mortar, on the other hand, is designed for repairing concrete structures. It has a much higher strength compared to masonry mortar, typically ranging from 5000 to 9000 psi. This high strength makes it suitable for specialized repair purposes but not for laying masonry units, as it can be too strong and cause the units to snap.

Key Differences

• Composition: While both types of mortar contain sand and cement, masonry mortar includes lime and finer mason sand, whereas repair mortar is formulated for higher strength.
• Purpose: Masonry mortar is used for building and binding masonry units, while repair mortar is used for repairing concrete structures.
• Strength: Repair mortar has a significantly higher strength (5000 to 9000 psi) compared to masonry mortar.

Choosing the Right Mortar

When selecting a mortar for masonry work, look for the ASTM C270 standard on the bag. This ensures you have the right material for laying and sticking together masonry units.

At the end of the day, understanding these differences helps ensure you choose the right mortar for your specific project needs.