Which mix is primarily used for type N mortar?

Type N mortar is commonly used in applications where moderate strength is required, such as in general masonry work for above-ground structures. It is known for its balanced properties, which include good workability and moderate compressive strength. The mix specified for type N mortar consists of one part Portland cement, one part hydrated lime, and six parts sand.

The inclusion of hydrated lime in the mix helps improve the mortar's flexibility and workability. Furthermore, the higher sand content ensures that the mortar has the right consistency for most masonry tasks, allowing it to be easily applied while maintaining enough strength for structural integrity.

In terms of the other mixes presented, they either contain an incorrect proportion of ingredients or do not align with the typical specifications for type N mortar. Some mixes lean towards higher cement content, which can create a stronger but less workable mortar, while others may lack the necessary lime needed to achieve the desired balance of characteristics that type N mortar is known for. Therefore, the combination of one part Portland cement, one part hydrated lime, and six parts sand is essential for achieving the properties that make type N mortar suitable for its intended applications in masonry.