Examkin

Question

Difficulty: MediumConcrete and Masonry Materials

In concrete construction, chemical admixtures are added to concrete batches to modify specific performance properties. Match each concrete admixture to its primary functional effect.

  • Air-entraining agentCreates microscopic bubbles to improve resistance against freeze-thaw cycles
  • SuperplasticizerSignificantly increases workability and slump without requiring additional water
  • RetarderSlows the rate of hydration to extend working time in high-temperature conditions
  • AcceleratorShortens initial setting time and speeds up early compressive strength development

Answer

Air-entraining agent matches with creating microscopic bubbles for freeze-thaw resistance; Superplasticizer matches with increasing workability without extra water; Retarder matches with slowing hydration in hot weather; Accelerator matches with shortening setting time and speeding early strength gain.
Each admixture fulfills a specialized role in concrete formulation: air-entraining agents generate micro-bubbles to prevent spalling from freezing moisture; superplasticizers boost slump and ease of placement without compromising the water-cement ratio; set retarders prolong working time when high temperatures cause premature stiffening; and accelerators hasten hydration for rapid strength gain in cold temperatures.

Step-by-Step Solution

1
Analyze the operational role of each concrete admixture in trade practice.
Air-entraining agents generate microscopic voids to protect against frost damage; superplasticizers enhance fluid flow without decreasing mix strength; retarders extend workability under high temperatures; accelerators speed up hydration in cold weather.
Each chemical additive is engineered to control a specific physical or chemical behavior of fresh and hardened concrete.
2
Pair each admixture from the left column with its corresponding performance description on the right column.
All four items are accurately paired based on their defined functions in concrete technology.
Correct alignment demonstrates understanding of building materials and mix design adjustments for diverse site conditions.

Key Concept

Functions and applications of concrete chemical admixtures (air-entrainers, water reducers/superplasticizers, retarders, and accelerators)
Estimated Time:1m 15s
Rate this question

Topics

Concrete and Masonry Materials

More questions from this topic