9.3. Volume of Admixture (if any)

Try these first

1. 1.

   Define what an admixture is.

   Hint

   Think about the purpose of adding something to a mixture.

2. 2.

   Name a type of admixture used to improve workability.

   Hint

   Consider substances that help concrete flow better.

3. 3.

   What is the primary purpose of adding an admixture to concrete?

   • To make it cheaper
   • To enhance its properties
   • To change its color

   Hint

   Focus on the benefits of using these materials in the mix.

4. 4.

   True or false: Trial mixes are unnecessary when using admixtures.

   • True
   • False

   Hint

   Consider the need for testing before large-scale implementation.

5. 5.

   Calculate the total amount of water needed for a concrete mix that includes a superplasticizer if the original water requirement is 250 kg, and the superplasticizer allows a reduction of 15%.

   Hint

   What does '15% of 250 kg' mean?

6. 6.

   You are conducting a trial mix and added a plasticizer which increased the slump from 40 mm to 90 mm. Discuss what considerations you should make for your actual production batch.

   Hint

   How does increased workability affect the overall mix?