As a ready-mix producer, you need to be prepared to handle a variety of problems to ensure your concrete doesn’t get rejected at the job site. One of the most challenging issues you will face is an air reading that is too high for the job specifications. When you need to increase the density of your concrete mix by removing entrapped/entrained air, an air detrainer can be a helpful product, but only if it’s used with careful attention to detail. Here are some common mistakes to avoid when using an air detrainer, such as Frtiz-Pak Air Minus.
Not Adding Enough Detrainer
Superplasticizers, water reducers, and obviously air entrainers will increase the entrained air in your concrete. When these products are present, adding a regular dose of an air detrainer may not be enough to counteract their effects on the mix. If you’ve been unable to reduce the amount of entrapped air in your mix with an air detrainer, it may be necessary to add a very high dose.
Mixing at a High Speed
Unlike other concrete admixtures, air detrainers should not be mixed at high speeds for more than a couple of minutes. Mixing at high speeds creates foam in the concrete mix, which increases the air content. To avoid creating excess foam during the mixing process, add the air detrainer, mix on high for 2-3 minutes, and then mix at a slow speed or ‘transit speed’ for another 3 minutes. This will help reduce the amount of foamed air caused by overmixing.
Testing the Mix Too Soon
Air detrainers require time to settle into the mixture before testing. If you test the concrete before the detrainer has had the opportunity to work, you will likely get a higher air content. For the most accurate reading, let the concrete rest for 5 to 10 minutes after you finish mixing. This ensures that the air detrainer has time to release the entrapped air and reduce the air content of the mix.
Unfortunately, not every load can be saved by an air detrainer, even if you avoid these mistakes and use best practices. If you have questions or concerns about adding an air detrainer to your load, check out our product guidelines or give us a call. We are always happy to answer your questions and help you better understand our products.
Fritz-Pak Corporation is a member of the American Concrete Institute, the National Ready Mixed Concrete Association, the American Society of Concrete Contractors, including the Decorative Concrete Council, the American Concrete Pumping Association, and the International Packaged Concrete Manufacturer’s Association