These are some of the most Frequently Asked Questions (FAQs) about Roadmaster Volumetric Mixers. 

What is slump and why is it important?

Slump is a measure of concrete consistency with specific attention paid to the amount of water added to the concrete mix to increase ease of placement. In other words, the higher the slump, the wetter the mix. Adding water simply to increase slump will result in a loss of strength for the concrete and possibly surface erosion. Concrete should always be placed at a moderate slump — not more than 4 to 5 inches — unless a water-reducing admixture is used for strengthening purposes.

What are the recommended mix proportions for good concrete?

While good concrete can be produced using a wide range of mix proportions, a good general rule of thumb is the rule of 6s:

  • A minimum cement content of 6 bags per cubic yard of concrete
  • A maximum water content of 6 gallons per bag of cement
  • A curing period that is a minimum of 6 days
  • An air content of 6 percent
What is the calibration process for a volumetric mixer and why is it important?
To calibrate, it is necessary to weigh and record the mixer’s output for each material used. This establishes gate settings and ensures the customer is receiving the proper pour mix.
Why is an aeration system necessary in the volumetric mixer’s cement bin?
The cement can pack down because of density changes and this can cause cement to feed improperly, if at all. The aeration system keeps the cement’s consistency constant. 
What makes Roadmaster Volumetric Mixers different?
Standard service problems are all but eliminated due to our bolt-on design, which improves dependability and requires 20 to 25 percent less maintenance than comparable mixers. 
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