In concrete masonry, which of the following increases compressive strength?

In concrete masonry, which of the following increases compressive strength?

• A. Sand
• B. Lime
• C. Cement
• D. Air Entrainment

Answer: (C)

In concrete masonry, the key factor that raises compressive strength is the cementitious binder in the mortar. Cement binds the sand and the masonry units together, forming a hard, cohesive matrix. Increasing the cement content strengthens that matrix, reduces porosity, and improves adhesion between the units, which directly boosts the masonry’s ability to carry loads. Lime is a softer binder and yields lower compressive strength, so it doesn’t provide the same strength gain. Sand is an inert aggregate that helps fill space but doesn’t increase strength as effectively as more cement. Air entrainment adds tiny air voids to improve durability in freezing conditions, but those voids reduce the material’s load-carrying capacity. So, the best way to increase compressive strength is to use more cement in the mortar.

In concrete masonry, the key factor that raises compressive strength is the cementitious binder in the mortar. Cement binds the sand and the masonry units together, forming a hard, cohesive matrix. Increasing the cement content strengthens that matrix, reduces porosity, and improves adhesion between the units, which directly boosts the masonry’s ability to carry loads. Lime is a softer binder and yields lower compressive strength, so it doesn’t provide the same strength gain. Sand is an inert aggregate that helps fill space but doesn’t increase strength as effectively as more cement. Air entrainment adds tiny air voids to improve durability in freezing conditions, but those voids reduce the material’s load-carrying capacity. So, the best way to increase compressive strength is to use more cement in the mortar.