Concrete Mix

The Attributes of a Good Concrete Mix

How to Design the Right Mix for Your Project

Special Concrete Mix Designs

Related Information:

When most contractors think about concrete mix design—if they think about it at all—the first thing that comes to mind is "bags" or "sacks." In the old days, when most concrete was mixed on site, cement was purchased in bags. A bag is 94 pounds of cement—about 1 cubic foot. But if you order a 6-sack mix, all that tells you is how much portland cement is in the mix. That mix could be completely wrong for your application and could even be inferior concrete. What slump do you need? What strength? Do you need entrained air? What happens if the day is particularly cold or hot? What size of aggregate is best? Should you ask for fly ash in the mix?

The right concrete mix ratio can solve problems or it can create them. What you really want in a concrete mix is one that is easy to place, strong enough to meet the needs of the application, durable for the life of the floor or wall, and that will look good when you're done with your decorative efforts. Don't rely on bags! Rather than only specifying how much cement is in the mix we should be specifying things like permeability, shrinkage, workability, pumpability, stampability, and stainability.

Throughout the following sections, one thing will become very clear: good concrete is good concrete and decorative concrete needs to be very good concrete. For decorative concrete we are seldom looking for high strength, so the wise contractor will focus on low permeability and low shrinkage. If you get concrete with those attributes, it would be rare indeed that you would have to worry about strength.