8.2. Tests for Mineral Admixtures

Try these first

1. 1.

   What is the purpose of the Pozzolanic Activity Index (PAI)?

   Hint

   Remember what PAI assesses in concrete performance.

2. 2.

   How is fineness measured in mineral admixtures?

   Hint

   Think about common methods of evaluating particle size.

3. 3.

   What does the Pozzolanic Activity Index measure?

   • Reactivity with water
   • Reactivity with calcium hydroxide
   • Particle size

   Hint

   Focus on what property the PAI is assessing.

4. 4.

   True or False: Higher fineness in mineral admixtures improves their reactivity.

   • True
   • False

   Hint

   Remember the relationship between size and surface area.

5. 5.

   A particular mineral admixture exhibits a PAI of 0.75. How does this affect your decision to use it in concrete, especially for a highly reactive environment?

   Hint

   Think about what PAI indicates regarding performance.

6. 6.

   You have two mineral admixtures, one with high fineness but low specific surface area due to compacting, and another with low fineness but high specific surface area. Which would you choose for high-performance concrete and why?

   Hint

   Connect the relationship between fineness and specific surface area to reactivity.