Concrete pavements can perform for many years with minimal maintenance and repair costs. However, there are exceptions, and even the most well-intended design and construction effort may result in failures and distress. The deterioration of concrete pavements caused by moisture intrusion and chemical attack (from deicing chemicals) can be a serious problem in northern states.
Moisture Intrusion
When water freezes it will typically expand 9% of its liquid volume. Therefore, when moisture saturates the surface of concrete and then freezes, it causes damage resulting in: scaling, minor flaking, pop-outs, and delamination.
A note regarding pop-outs:
Some pop-outs may be expected, depending on the type of aggregate used in a concrete production. Most of the aggregate readily available in this marketplace was deposited by glaciation. Glacial sand and gravel contain particles from all sorts of different rock. Unfortunately, some of the rock is soft and absorptive. This rock will expand and break up when it freezes, resulting in a pop-out. If glacial aggregate is used in your concrete, you can expect some surface pop-outs leaving blemishes. However, some people may find these pop-outs aesthetically undesirable. Pop-outs will not affect the structural serviceability of the concrete placement now or in the future.
Chemical Effects
Concrete is especially vulnerable to damage caused by deicing chemicals. Salt and other deicing measures not only break down the concrete chemically, but they lower the freezing point of the water within the concrete matrix. This circumstance results in a denser saturation of the matrix, causing increased expansion of the ice crystals during any freeze-thaw cycles the concrete may experience.
Cracks
Cracks can develop from shrinkage and thermal stress and ground movement. Typically, these cracks are not detrimental to the structural serviceability of the concrete. Reinforcement, in the form of steel bars, fiberglass bars, or polypropylene fibers, are incorporated into the concrete at the time of placement to hold potential cracks together.
Maintenance
Apply a sealer to keep water from penetrating into the surface of the concrete. Just as we protect our wood decks from the ravages of weather and chemical attack, we need to protect our concrete. Water¬ repellant coatings and sealers will reduce damage from freeze-thaw cycles and salting. Newly cured concrete should air-dry for 28 days prior to sealing. Most sealer applications are effective for about two years. When water no longer beads on the surface it's time to reapply a sealer. The value ofyour concrete placement far exceeds the cost of sealing. Note: Driveways installed in the fall of the year will unlikely have the opprtunity to be sealed before freezing up due to cold temperatures.