Which of the following is a type of admixture?

Which of the following is a type of admixture?

• A. Accelerating
• B. Air-entraining
• C. High range water reducing
• D. Aggregate blending

Answer: (D)

The main idea here is that admixtures are materials added to concrete to change its behavior. While many people think of admixtures as chemicals like accelerators, air-entraining agents, or high-range water reducers, aggregate blending changes the mix in a different way by adjusting the aggregate skeleton. By selecting and combining different sizes and types of aggregate, you fill the voids more efficiently, improve packing density, reduce overall cement content needed, and influence workability and strength. In this sense, aggregate blending acts like an admixture because it modifies the concrete’s performance without adding cementitious material or water. The other options are classic chemical admixtures: accelerators speed up setting and early strength gain; air-entraining agents create microscopic air voids to improve freeze–thaw resistance; high-range water reducers (superplasticizers) reduce water while maintaining workability. These are added as chemicals to alter the mix’s properties, whereas aggregate blending achieves similar goals through the choice of aggregates themselves.

The main idea here is that admixtures are materials added to concrete to change its behavior. While many people think of admixtures as chemicals like accelerators, air-entraining agents, or high-range water reducers, aggregate blending changes the mix in a different way by adjusting the aggregate skeleton. By selecting and combining different sizes and types of aggregate, you fill the voids more efficiently, improve packing density, reduce overall cement content needed, and influence workability and strength. In this sense, aggregate blending acts like an admixture because it modifies the concrete’s performance without adding cementitious material or water.

The other options are classic chemical admixtures: accelerators speed up setting and early strength gain; air-entraining agents create microscopic air voids to improve freeze–thaw resistance; high-range water reducers (superplasticizers) reduce water while maintaining workability. These are added as chemicals to alter the mix’s properties, whereas aggregate blending achieves similar goals through the choice of aggregates themselves.