Image of mobile concrete mixer with crew performing road work


Mobile Concrete Mixers / Volumetric Mixers / On Site Concrete Mixers - How Do They Work?

Whether you call it a mobile concrete mixers, volumetric mixer, or a site concrete mixer, you’re probably aware of these agile units cruising around jobsites all over the world. Designed to add versatility to a project, this equipment provides precision and flexibility to a variety of concrete applications. But how do they work? Read below to learn more about this exciting automated machinery.


How A Mobile Concrete Mixer Works

The simplest way of thinking of volumetric concrete mixers is to imagine a mobile batch plant on wheels. That is how much freedom and convenience each volumetric mixer offers. The technology was first developed in the 1960s when it became apparent that being able to mix on-site was far more convenient than waiting for a Readymix truck.

Since then, volumetric mixers have come a long way. You could even argue they have become unrecognizable compared to the early versions. Now equipped with precision technology and utilizing automation to streamline workflows, volumetric mixers are gaining popularity with companies looking to leverage technology to improve quality and productivity.


A Batch Plant on Wheels

Volumetric mixers are mobile concrete batch plants on wheels. Each truck is equipped with separate compartments for the ingredients a construction crew needs:

  1. Sand
  2. Aggregate
  3. Cement or Secondary Cementitious Materials
  4. Water
  5. Admixture(s)

The compartments, or bins, for sand and aggregate generally require the most space. The next largest compartment tends to be used for cement or secondary cementitious materials. Volumetric mixers have their own water tanks, making crews independent in even the most remote locations. Plus, ProAll mixers also come standard with two admixture tanks and the ability to install two more.

To accommodate the characteristics of the sites where your team is normally working and the amount of concrete you need, manufacturers like ProAll offer on site concrete mixers in a range of sizes and configurations. Some are smaller and agile enough to work in restricted city spaces; others are large enough to carry substantial supplies that ensure large projects can be completed without hitches.


Fresh, High-Quality Concrete, Every Time

Once the compartments are filled, the mobile mixer travels to the site loaded with separate ingredients. Actual concrete mixing starts on-site and only when the crew is ready.

Getting the mixture just right used to be one of the trickier parts of the job, requiring years of experience and understanding of the ingredients. This job often fell to an experienced operator.

Automation has made mixing easier. Thanks to ProAll’s Commander control system, crews simply use a touchscreen to select the mix they need from a predefined list, and the machine does the rest. Once the mix design has been set and pouring can begin, the gates open to just the right position to allow the sand and stone to dispense in the correct quantity. The Commander control system also manages and adjusts the flow of any admixtures and the water and controls the quantity of cement powder dispensed.

As the materials pass under the cement bin, the correct amount of cement is added to ensure the mix design consistently meets specifications. All necessary materials come together in the mixing bowl and flow through to the auger where they are combined to create a homogenous concrete mixture. Once the concrete has been thoroughly combined, it will be carried to the discharge chute, and the concrete is poured.

This may sound like a lengthy process, but in reality, it is far more streamlined than using premade concrete. An on site concrete mixer delivers fresh concrete to exact specifications on every pour. There are no delays, and none of the materials are wasted. Any material remaining in the bins from the previous project can be used on the next job.


What Types of Concrete Can you Make with an On Site Concrete Mixer?


The short answer to this question is simple: volumetric mixers can make any type of concrete you need.


Standard Concrete

In many cases, standard mixtures are required for the foundations of buildings or as part of road construction projects. Mobile mixers deliver these mixtures reliably as and when construction crews need them.

If you are running large projects in remote locations, you can even set up a mobile mixer to work continuously. All that is required for a continuous pour is a consistent supply of raw materials, and the mixer truly becomes a batch plant. As long as the raw materials do not run out, your crew can keep pouring. The result is a highly flexible operation that will never be held back by a delay in concrete delivery.


Rapid-Set Concrete

Standard concrete takes about 48 hours to cure and develop enough strength for work to continue. However, in some cases, that is simply too long, and crews need the option to pour fast-setting concrete. The use of rapid-set concrete is becoming more and more popular due to the logistical advantages of a faster setting time, and mobile concrete mixers are the only machines engineered to work with this application. Rapid-set concrete offers reduced shrinkage and faster strength gain while reducing labour and project costs.


Using Admixtures

Every ProAll on site concrete mixer comes equipped with tanks for admixtures. The most commonly used admixture in volumetric mixers is used for air entrainment, where microscopic air bubbles are intentionally incorporated into concrete during mixing. This process is highly recommended for almost all types of concrete and it serves primarily to improve freeze-thaw resistance of concrete when it is exposed to water and ice.


Ready for Anything

Volumetric concrete mixers can take on any construction project that requires concrete. Whether you are looking to pour concrete for backfill or soil stabilization or need to pour gunite to build a swimming pool, volumetric mixers can do the job.

Their versatility has made them the tool of choice for commercial and industrial applications of any size. They are even found in remote oil fields, thanks to their operational flexibility.


What are the Benefits of an On Site Concrete Mixer?

Out of all the benefits of a on site concrete mixer, one stands above the rest, and that is the benefit of pouring high-quality concrete every single time. When crews use traditional barrel mixers, any delay tends to lower the quality of the concrete that is poured.

And even with the most exacting planning, delays are likely. Think of the trip from the batch plant to the job site, for example. Heavy traffic can delay the trip, leaving crews waiting on-site and most likely altering the characteristics of the mix, especially in extreme temperatures. Of course, experienced crews can keep the concrete workable, but it simply will not have the same quality it had before.

Volumetric mixers also help reduce waste. Crews never need to throw away leftover concrete because there are simply no leftovers. You only pour the exact amount of concrete you need, and any ‘leftovers’ become raw materials for the next job. At the same time, you cannot run out of concrete just before the job is finished as long as there are enough raw materials. The results are obvious: jobs are finished on time and on budget. Reducing construction waste also helps to minimize the industry’s carbon footprint.

Changing mix designs is simple and straightforward. Rather than ordering yet another batch of concrete from a batch plant and waiting for it to arrive, operators simply use the Commander Control System and start pouring a new mix. The changeover is fast and convenient.


The Bottom Line

Volumetric concrete mixers bring the best of modern construction technology to job sites anywhere. They work by storing the ingredients of concrete in separate compartments on the back of a truck and only starting to mix when a project is ready for concrete to be poured.

They streamline any project by pouring concrete as and when it is needed, minimizing delays and unnecessary waiting times. Because there is no concrete waste, they also help reduce project costs.

And here is another consideration: thanks to automation, volumetric mixers can be operated safely and precisely after a small amount of training. That means construction crews can operate more flexibly and meet their clients’ needs quickly and easily.

To find out more about how a ProAll mixer can transform your construction project, contact us today.