Why concrete cracks and how to prevent it
Submitted by Mr. Concrete of Indiana, Inc.
It is very common for concrete to have cracks, scaling, crazing and pitting. All concrete has a tendency to crack, and it is not possible to produce completely crack-free concrete. Concrete expands and shrinks with changes in moisture and temperature. The overall tendency is to shrink, and this can cause cracking at an early age of the concrete. Irregular cracks are unsightly and difficult to maintain but generally do not affect the integrity of concrete.
Control joints in concrete are simply pre-planned cracks. Control joints create a weak place in the slab so that when concrete shrinks, it will crack in the control joint instead of randomly across the slab. The American Concrete Institute addresses this issue. “Even with the best floor designs and proper construction, it is unrealistic to expect crack-free and curl free floors. Consequently, every owner should be advised by both the designer and contractor that it is normal to expect some amount of cracking and curling on every project, and that such an occurrence does not necessarily reflect adversely on either the adequacy of the floor’s design or the quality of its construction.”
The most popular explanation for the concrete cracking is the freeze-thaw cycle in the winter. It is recommended to use sand on all concrete instead of salt. Salt will facilitate the freeze and thaw cycles that will then create the problem with pitting and cracking. When the temperature reaches 18 degrees, the concrete will freeze. At 35 degrees it will melt and cause the cracking, pitting, crazing and scaling.
Concrete also cracks in the extreme sun, as it heats the concrete and causes it to expand. During the day, the sun heats, expands and moves the concrete. At the end of the day, the concrete contracts and regresses to its original, unbaked position. A homeowner can help to prevent cracking, scaling, crazing and pitting by yearly applying a good acrylic silicone solvent based sealer to their concrete. The cracks can also be repaired with an epoxy injection, dry packing or routing and sealing techniques to stabilize the cracks.
Mr. Concrete of Indiana, Inc. has provided specialized concrete, aggregates and related solutions to the communities of Indiana in both residential and business environments for more than 35 years.
As of Aug. 2, 2011, this service provider was highly rated on Angie’s List. Ratings are subject to change based on consumer feedback, so check AngiesList.com for the most up-to-date reviews. The views expressed by this author do not necessarily reflect those of Angie’s List.