1. Free Fall Non-Tilting Reversible Mixer

Try these first

1. 1.

   What is a free fall mixer?

   Hint

   Think about how gravity works.

2. 2.

   What does a reversible mixer do?

   Hint

   Consider how it can mix and then empty.

3. 3.

   What type of mixer requires a minimum slump of 50 mm?

   • Power mixer
   • Free fall mixed
   • Both

   Hint

   Think about the limitations of gravity mixers.

4. 4.

   True or False: Pan mixers use horizontal shafts to facilitate mixing.

   • True
   • False

   Hint

   Recall the structure of different mixer types.

5. 5.

   A construction site needs to produce 240 m³ of concrete using a power mixer that has a cycle time of 3 minutes. How many hours will it take if the efficiency is 75%?

   Hint

   Calculate the effective real output based on efficiency and thus the total needed batches.

6. 6.

   If a pan mixer has a mixing duration guideline of 5 minutes per batch, but you mixed for only 3 minutes, what issues might arise?

   Hint

   Think about what mixing does to distribution and uniformity.