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Would You Drink it?

The rule of thumb when you’re looking at an aggregate for use in your mix designs is to pay attention not only to its dispersion across the screens, but more importantly the percentage of material retained on the pan. The retention on the pan passing the #100 sieve being usually around 6 percent or less. The reason for this is that the particle size passing the 100 screen is small enough that it can actually inhibit the crystalline growth that is a byproduct of cement hydration. The finer the mix, the more cement is needed to cover the aggregate particles. Another potential culprit for adding excessive fines, is your mix water. Ideally, your mix water should be potable as a result of it being either city water or has gone through a filter and softening process. Pulling water directly from a well could be as detrimental as having high fines content in your aggregates. If you’d like to do an in-house check, take a small amount of your mixer water and place it in a clear glass cup. Place a coffee filter over the top of the glass and let the water evaporate. When totally evaporated see what’s left, if it’s clear that’s great.  If it’s hazy or you can see deposits, you may want to address your filtration methods. For more information contact Production Specialist Mike Maroney.