I always get asked to repair cracks in concrete driveways, after all its what I do. Most cracks occur in concrete from movement underneath the slab. The crack occurs at the stress point in the slab. Concrete is so hard that it really has no flexibility to it so it has to give way by breaking.
The time comes to repair and should be done before old man winter makes it worse. Water can get into the crack, freeze and break the concrete away exposing more problems. The crack will need to be chased then bonded with repair material that is stronger than concrete. If the slab is still moving this can be a problem down the road as the concrete can break again. Slab jacking can help bring the slab level again and remove some of the stress so the repair can have better success. Once bonded the crack can then be filled with concrete.
Once you fix the crack and it is filled you still have an ugly crack. You can then coat with protective coating to hide all the repairs and make your driveway look new again!
When water freezes it puts pressure in the pores of the concrete. If the pressure developed exceeds the tensile strength of the concrete, the cavity will dilate and rupture. The accumulative effect of successive freeze-thaw cycles and disruption of paste and aggregate can eventually cause expansion and cracking, scaling, and crumbling of the concrete.
Deicing chemicals for pavements include sodium chloride, calcium chloride, magnesium chloride, and potassium chloride. These chemicals reduce the freezing point of the precipitation as it falls on pavements. A recent trend has seen a wide variety of blends of these materials to improve performance while reducing costs, and best practice indicates that a liberal dosage greater than four percent in solution tends to decrease the potential for scaling of pavement surfaces. The high concentration of deicers reduces the number of freezing and thawing cycle exposures to the pavement by significantly lowering the freezing point.
When water freezes, it expands about 9 percent. As the water in moist concrete freezes
In summary, water soaks into your concrete then freezes will cause damage to concrete if it is weak and not strong enough to stand up to the expansion. This is why we need to protect the concrete from the water penetration. Pour concrete installation (finishing) can accelerate this problem as well. Sealing the concrete or adding a protective coating is your best defense !