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NederlandsMix-on-Site Concrete Trucks: How to Run a Continuous Pour
A mix-on-site concrete truck, or volumetric mixer, produces concrete continuously at your job site instead of delivering it pre-mixed from a plant. That makes it well suited to continuous pours, where fresh concrete has to keep flowing without the stop-start of waiting on successive ready-mix trucks. Volumetric mixers deliver top-quality concrete with less equipment and fewer trucks on the road, and crews stay productive because they are never waiting on the next delivery.
What a Mix-On-Site Concrete Truck Does
A mix-on-site concrete truck carries sand, stone, cement and water separately and combines them through a continuous auger at the moment of placement. Because the concrete is made on demand, you get a steady stream of fresh material at the correct slump, with no returned loads and no setting clock. For a continuous pour, that on-demand control is the whole advantage: the operator can stop and restart production to match the crew’s pace without compromising the mix.
McQuay Construction is an industry leader in using volumetric trucks for continuous pours. Through trial and error the company helped perfect the process, and its five-step approach is a practical blueprint for running one.
1. Take control of the equipment
“It is much easier when you own all of the equipment,” says Zach McQuay. McQuay Construction owns everything used to produce concrete on site: the concrete pump, the volumetric concrete mixers, water trucks when needed, pneumatic cement powder trailers, and wheel loaders. Owning the full chain simplifies scheduling, because you are not working around the owner of the pump truck or the cement supplier.
2. Stage the Equipment
To run a continuous pour you discharge into a concrete pump, so staging matters. Choose where the pump truck sits, then position each volumetric concrete mixer truck in a Y-pattern off the corner of the pump, leaving room for a loader to work between them and feed materials. Position the pneumatic cement trailers so they can reach the mixers but be swapped out without stopping production, and place any water truck in front of or beside the pump.
3. Source the water
Water is a critical ingredient, and a continuous pour needs an ample, uninterrupted supply. In the best case, water comes from a nearby hydrant with hoses run to the volumetric concrete mixers. If no hydrant is available on site, a water truck shuttles water to the mixers.
4. Stage the material stockpiles
“The material placement is very important,” says McQuay. Stockpile enough material to complete the job on site, spaced so the loader can feed the mixers with minimal movement. McQuay keeps rock on the right side and sand on the left of the volumetric mixer trucks. Placing the piles on concrete where possible eliminates material loss.
5. Ensure cement powder availability
McQuay consistently pours a 3,500 psi mix design at 120 cubic yards an hour with two volumetric trucks, which takes careful planning. Rock and sand are easy to stockpile; cement powder is the limiting resource and must be secured from a vendor in advance. McQuay stores powder in silos and hauls it to the site in pneumatic cement trailers that hold enough for just over 90 cubic yards. “We constantly make sure there is enough powder for today and tomorrow,” he says.
Perfecting Continuous Concrete Pours
Learn how McQuay Construction uses volumetric mixers to set up and run continuous pours for quality, consistent concrete. Discover their five-step process for top results and easy operation.
What a Continuous Pour Needs
Pulling those five steps together, a successful continuous pour comes down to three things, and a mix-on-site concrete truck delivers each: steady output matched to the crew’s placement speed, the ability to adjust the mix without stopping, and no dependence on drum-truck delivery timing. When set up properly, one operator can run two trucks by remote, and once production starts it does not stop.
Proper Setup Yields Quality Results
Producing a continual flow of fresh concrete eliminates the common problem of cold joints and seams. “If the ready-mix truck needs to stop for 20 minutes while the crew catches up, you have to add another 10 gallons of water to get the mix back to the right consistency,” McQuay says. “With the volumetric truck, we can simply hit stop. There is fresh concrete available as soon as you are ready to go again.” Adding water to a ready-mix load compromises strength; mixing on demand holds the concrete at the ideal slump with no added water, so the result keeps its maximum psi strength with no variation.
FREQUENTLY ASKED QUESTIONS
What is a mix-on-site concrete truck?
A mix-on-site concrete truck, or volumetric mixer, carries sand, stone, cement and water separately and combines them through a continuous auger at the job site. It produces fresh concrete on demand rather than delivering a pre-mixed load, which makes it ideal for continuous pours.
Why are volumetric trucks good for continuous pours?
They produce a steady stream of fresh concrete at the correct slump with no setting clock. The operator can stop and restart production to match the crew’s pace, which eliminates the cold joints and water-added strength loss that happen when ready-mix trucks have to wait.
How many volumetric trucks does a continuous pour need?
With proper staging, two volumetric trucks run by a single operator can sustain a continuous pour, pouring on the order of 120 cubic yards per hour at a set mix design. The operator monitors the water-to-cement ratio throughout.
What limits a continuous pour?
Material supply, especially cement powder. Rock and sand are easy to stockpile on site, but cement powder must be secured in advance and kept flowing from silos and pneumatic trailers, since running out stops the entire operation.
Does mixing on site improve concrete quality?
Yes. Because the concrete is made fresh and never waits, there is no need to add water to restore workability, so it holds its design slump and maximum psi strength with no consistency variation and no cold joints.
If the ready-mix truck needs to stop for 20 minutes while the crew catches up, you have to add another 10 gallons of water to get the concrete mix back to the right consistency. There is nothing you can do about it. With the volumetric truck, we can simply hit stop. There is fresh concrete available as soon as you are ready to go again.
One Operator, Two Trucks, Continuous Concrete
With a proper setup, a single operator can control two volumetric trucks via remote, ensuring a nonstop, continuous pour for your projects.
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