Residential concrete information

2019-12-21

Ever wonder if you should call it “concrete” or “cement”?
Concrete is not the same as cement. Concrete is a combination of cement as a binding agent, chemical additives, water and mineral. Cement, a combination of finely ground materials, hardens when mixed with water to become the "glue" in concrete.

Why do concrete surfaces crack?
Sometimes concrete loses moisture too quickly as it cures, causing surface cracks. Sometimes the concrete slab is preventing from moving in response to substrate movement, causing it to crack. Other times external water (for example, rain or snow) enters into the concrete capillaries and freezes, causing the capillaries to expand until a thaw comes along and melts the internal ice, causing structural cracks over a season. And these are just a few of the possibilities...

Why does my concrete surface make so much dust?
A simple explanation is that, as it was finished, too much water was remaining in the concrete. The cause could have been too little time allowed for curing, inadequate ventilation, trying to finish the concrete with too much moisture on the surface (either bleed water or condensation), inadequate protection from weather, or concrete placement over a non-absorptive or under-absorptive surface. In any of these cases, excessive or reactive moisture weakens the concrete so it "dusts" easily when used.

What should I do about driveway stains?
There are a number of good driveway stain removers on the market. Before leaving the house to get one, however, try this: go to your kitchen cabinet and grab your favorite grease-busting dishwashing liquid. Brush it full strength on the stains with a stiff-bristled push broom. Let it set for a few minutes, then rinse with water under moderate or high pressure (a garden hose with a jet sprayer should do it). If you don't see a significant reduction in the stain, call your local concrete professional.

Is there any good way to “seal” a concrete driveway?
Yes. Some people prefer a decorative acrylic sealer. Many prefer a penetrative sealer that will chemically react with concrete to repel water, or in some cases petroleum products. The product options are such that you'd probably benefit talking them over with a concrete professional familiar with driveway treatments--like The MJA Company.

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