Choosing the correct concrete for your project
A basic concrete mix contains cementatious materials, water, aggregates and admixtures.
Portland cement, often referred to as simply cement, is the powder that gives the concrete its bonding characteristics. Other types of cementatious materials are fly ash, ground granulated blast furnace slag, and microsilica. These products are added to the concrete to affect desired characteristics of the concrete such as finishability, strength, and/or set times.
In our area of Northern Michigan, we offer two differnet types of coarse aggregate. The first type is a "local aggregate" or "round stone", commonly used in all concrete that is not exposed to the weather and elements of nature. Concrete used in garage floors, basement floors and foundations have "round stone" coarse aggregate. The other main coarse aggregate is crushed limestone. It is mainly used in exterior concrete such as a driveway, sidewalk, patio, or porch top. The aggregate used does not affect the strength of the concrete.
Admixtures are used to control certain characteristics of the concrete. An air entraining admixture is a good example of a commonly used admixture. This particular admixture usually is in a chemical form and is added to the mix at the plant during the loading process. Air entrainment is neccesary in exterior concrete which is exposed to the elements of nature, particularly moisture and the freeze-thaw cycle. Our mixes are all air entrained unless ordered otherwise. Typically, concrete that is to receive a hard troweled finish, such as a basement floor or pole barn floor would be ordered with either "half air" or "no air". Retarders, accelerators, and water reducers are other common admixtures. Fiber reinforcement is another form of a concrete admixture. Fibers are mainly used to control shrinkage cracks. Visit the Fibermesh website listed in the "Links" section of this website to see all the advantages of using fiber reinforcement.
Common ways to refer to concrete mixes would be by the "psi" or strength of the mix. For instance, commonly used mixes are 2500psi, 3000 psi, 3500 psi, and 4000 psi mixes.
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