MOST POPULAR QUESTIONS ABOUT VOLUMETRIC MIXERS

Volumetric concrete technology focuses on batching based on volume rather than weight. All equipment calibrates by weight with the material delivered to the mix auger by volume. This method produces a proportional accuracy of plus or minus one percent.

There are two main contrasts between traditional batch plants and volumetric operations:

1. Traditional Batch Plants Stay In A Fixed Location.

There, aggregate bins and cement silos feed necessary materials for a specified mix design into the plant where water and admixtures are added. The materials are weighed then mixed into concrete inside the plant before a discharge chute moves it into a barrel mixer for delivery.

2. Materials Blend Continuously & On-Demand With Volumetric.

With volumetric technology, all materials — from sand and stone to cement powder and water — continually blend on demand. This means the mixer can be started and stopped as needed while the aggregates stay separate in their respective compartments. This is unlike traditional mixing methods which blend all materials at one time.

Here, calibration focuses on the individual materials, such as sand and stone, rather than the mixer itself. All materials used in concrete production should be calibrated at least once a year. The typical order of calibration is:

1. Cement
2. Sand
3. Stone

1. Cement Calibration

It’s recommended you complete three trials to five trials when calibrating cement. Remember to record:

• Discharge time in seconds;
• Counts; and
• The weight of materials in pounds.

The overall goal of the trials is to verify accuracy within plus or minus one percent.

2. Sand Calibration

To calibrate sand, discharge a specified number of sand counts into the chosen bucket. Timing sand or stone isn’t necessary as the release is based on cement. Record counts as a number and weight of material in pounds during this process.

3. Stone Calibration

To calibrate stone, empty the sand bin and load rock. The process is the same as calibrating sand, including the number of trials.

1. High Quality Concrete

Because all concrete is mixed on-site, it’s fresh and eliminates the chance of a hot load. Concrete produced by Cemen Tech volumetric mixers consistently has a higher breaking strength than traditional ready mix.

2. No Waste

Volumetric concrete production allows you to pour a precise amount, thus stopping overages, shortages, and short-load fees.

3. Change Mix Designs As Needed

The ability to change mix designs allows you to make the change as the project dictates without scheduling or rescheduling a new load of concrete. For example, one project calls for a low strength fill while another specifies a 5,000 PSI. The computers on a Cemen Tech mixer let you store hundreds of calibrations, mix designs, and project tickets.

4. Less Crew Downtime

Crew downtime is costly for any business. Yet, the on-demand nature all but eliminates this issue as crews work as the concrete pours.

5. Pay Less For Concrete Deliveries

Another advantage of volumetric mixers compared to traditional barrel trucks is no longer paying extra for after-hours and/or weekend deliveries. This allows a producer to determine their own schedule, not schedule work based on someone else’s timeframe.

6. More Eco-Friendly

By using a fixed amount of water per mix and only running the truck and mixer as needed, this type of concrete production has a lesser environmental impact.

7. Added Business Versatility

Although companies generally manufacture volumetric mixers using similar templates, the mixers may vary based on type, size, and options to fit differing business needs.

8. Increased Mobility

Whether it’s a trailer-mount or chassis-mount, these mixers provide the ability to reach locations barrel mixers usually can’t. They’re also compatible with any size of concrete pump which are often used for large-scale or continuous pours.

Many construction projects use concrete from volumetric mixers every day. Common examples include:

• Utility work, such as sewer and water;
• Road, street, and/or sidewalk repair;
• Construction in remote locations, such as new housing developments;
• Projects using fast setting concrete, such as airport runways or highway repairs; and
• Large pours with materials available onsite, such as commercial developments.

Numerous factors go into the potential growth of a company, but several which seem out of a producer’s control can be taken back by using volumetric technology. For example, three common pain points include:

• Minimum order requirements, such as needing 2-yards but paying for 5-yards;
• Paying a higher rate per yard for less than a full truck; and
• Scheduling multiple trucks if a project needs different concrete mix designs.

In turn, producing concrete by volume rather than in bulk allows a producer to sidestep these frequent issues by:

• Producing only what the project needs, down to a quarter yard;
• Equalizing material costs whether you pour one yard or 10 yards; and
• Allowing you to change the mix design and/or slump at any time.

Yes. ASTM C94 is the standard for weighing each ingredient, while ASTM C685 focuses on volume. Any equipment that meets either standard can produce quality concrete. However, the quality of volumetric concrete is governed by ASTM C685 and AASHTO M241, which includes extra regulations.

Comparative testing performed by Terracon found marginally higher strength gain in concrete placed by a volumetric mixer compared to a barrel or drum. ACI-certified technicians performed tests aimed to compare the mix properties for similar mix designs from volumetric mixers and drum trucks. Tests focused on air content, slump, and unit weight according to ASTM standards.