Portable concrete mixers are a common sight on construction projects. Sizes can vary from a 2-cubic-foot capacity to a 12-cubic-foot capacity, with larger models available with a tow package.
There are some jobs for which you will clearly need a ready mix truck, but Gary Wiebe, plant manager with Crown Construction, explains there are advantages to jobsite mixing. "A truck will charge a minimum for travel time and amount of concrete, but with a portable mixer there's no waste because you mix what you need. And you also always have on-time delivery with the portable mixer - when you mix your own concrete you get it when you want it," he says. "Contractors also have more control over the mix and can add more stone or cement to get the exact mix they want."
When deciding what size mixer to purchase, contractors should look at their typical job size. You can always mix a small batch in a larger mixer, but your productivity will be hindered if you choose a mixer too small for your company.
"Generally, if a contractor is doing a small patio or a job like that, a 4- to 7-cubic-foot mixer is fine. You'll see a lot of that size doing patch work, too," says Ed Varel, engineering project manager at Stone Construction Equipment, Inc. "When you get to the 9-, 10- and 12-cubic-foot mixers, you're doing something more than patch work. You might be doing work in a larger confined area project like a large patio, sidewalk, garage or platform."
Concrete mixers are fairly basic units and don't vary much from manufacturer to manufacturer, Varel says. But there are a few options and quality features to look for when choosing a jobsite mixer.
Make sure the concrete mixer you choose, whether it's a tow-behind unit or an attachment, is built with quality steel thick enough to offer you longevity and durability. A simple design with minimal consumable parts will ease maintenance. When choosing a tow unit, check for the proper tongue weight, tow package and safety chains to ensure safe towing.
Another safety issue concerns the mixer itself. "You want to make sure you have a drum lock so you can mix without the drum rotating into the dumping position," Varel says.
The decision between a steel mixing drum and a polyethylene mixing drum is something else to consider. Most units come standard with the steel drum, but manufacturers offer a poly option on some units. A poly drum has a higher price point but allows for fast and easy clean-up. Contractors mixing small batches or multiple batches a day will find a time-saving advantage with the poly drum.