6.13. Compatibility with Chemical Admixtures

Try these first

1. 1.

   What effect does silica fume have on water demand in concrete?

   Hint

   Think about the surface area of silica fume.

2. 2.

   What does fly ash do to the setting time of concrete?

   Hint

   Consider how the mixture behaves over time.

3. 3.

   What is one effect of silica fume on concrete?

   • Increases setting time
   • Increases water demand
   • Reduces strength

   Hint

   Consider the properties of silica fume.

4. 4.

   True or False: Fly ash can help with the short-term setting of concrete.

   • True
   • False

   Hint

   Think about delays caused by certain materials.

5. 5.

   If you are formulating a concrete mix for a construction project in a cold climate using fly ash, what strategies would you recommend to mitigate the extended setting times?

   Hint

   Think about how temperature and accelerators interact with setting times.

6. 6.

   Compare a scenario where you use metakaolin versus a mix with only silica fume. Discuss the impacts on workability and how you would adjust your admixture choices.

   Hint

   Reflect on how each affects viscosity.