Which factor directly affects the durability of fresh concrete?

Which factor directly affects the durability of fresh concrete?

• A. Air content
• B. Slump
• C. Temperature
• D. Color

Answer: (A)

Durability of concrete is shaped by how the pore structure handles water and aggressive agents over time. In the fresh mix, adding air through an air-entraining admixture creates a uniform distribution of tiny air voids that stay in the hardened concrete. These microscopic voids provide space for water to expand during freezing, which reduces internal stresses and limits cracking, giving better freeze-thaw durability. They also lower the material’s permeability, slowing the ingress of chlorides, sulfates, and other deleterious substances that can cause deterioration. That’s why air content directly affects durability. Slump affects workability, temperature influences hydration and early strength, and color is cosmetic, so they don’t relate to durability in the same direct way.

Durability of concrete is shaped by how the pore structure handles water and aggressive agents over time. In the fresh mix, adding air through an air-entraining admixture creates a uniform distribution of tiny air voids that stay in the hardened concrete. These microscopic voids provide space for water to expand during freezing, which reduces internal stresses and limits cracking, giving better freeze-thaw durability. They also lower the material’s permeability, slowing the ingress of chlorides, sulfates, and other deleterious substances that can cause deterioration. That’s why air content directly affects durability. Slump affects workability, temperature influences hydration and early strength, and color is cosmetic, so they don’t relate to durability in the same direct way.