Materials Used for Commercial Floors
Commercial or industrial floors tend to be large placements that are susceptible to curling and cracking. A lot of that can be controlled by using the right materials and in the mix designs. The key is to use the largest possible aggregate (since aggregate can't shrink), and to get a well graded aggregate (meaning there is aggregate of every size from large to small), and to use the lowest water content possible. Learn more about mix design.
Placeability and finishability are also critical to getting a good slab and there is a certain amount of trade-off necessary to accomplish these equally important goals of a durable floor that's easy to place. For an extensive explanation of good mix proportioning for commercial or industrial floors, check out Chapter 6 of ACI 302.1R-04. Here are a few important points:
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The maximum size of coarse aggregate should not exceed 3/4 the minimum clear spacing of the reinforcing bars in structural floors, or 1/3 the thickness of non-reinforced slabs. Aggregates as large as 1.5 inches, though, can often be used.
Fly ash is composed of tiny spherical glassy particles.
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Fly ash or slag cement commonly appears in commercial or industrial floors. These materials (along with silica fume) are called supplementary cementitious materials or pozzolans and have various purposes as a cement replacement. I have always refused to call pozzolans admixtures, although many people do. According to the strict definition from ACI, it would seem that pozzolans are admixtures because they are "a material other than water, aggregates, hydraulic cement, and fiber reinforcement, used as an ingredient of a cementitious mixture to modify its freshly mixed, setting, or hardened properties and that is added to the batch before or during its mixing." But to me, a pozzolan is really a cementitious material and therefore not quite the same as an admixture. Some call these materials mineral admixtures. I simply call them SCMs; you can decide what you want to call them, if you want to call them at all.
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A material sometimes used with commercial or industrial floors is expansive cement (also called shrinkage-compensating cement). Shrinkage-compensating concrete expands slightly while setting then shrinks back to its original size. When done properly this can eliminate cracking and increase the spacing of control joints but it requires anexperienced concrete contractor and ready mix producer to get everything to work properly.
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Hard, wear-resistant aggregates, such as quartz, emery, and traprock, as well as malleable metallic hardeners, are frequently used as surface treatments in commercial or industrial floors. They are applied to the top surface as dry shakes and finished into the surface of the floor to improve the abrasion resistance of the surface.
Steel fibers in concrete form a three-dimensional matrix.
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Reinforcement comes in various types, these include welded wire fabric (mesh) steel reinforcing bars (rebar), synthetic fiber reinforcement (0.75 to 1.5 pounds/cubic yard), and steel fibers (34 to 68 pounds/cubic yard). Synthetic fibers, commonly polypropylene, are primarily useful for preventing plastic shrinkage cracking. Some fibers, such as steel fibers can improve concrete flexural strength.
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