Winter can raise havoc with concrete sidewalks especially if you use salt as an ice melt. However, it's not such a daunting task to repair the cracks on your sidewalks by yourself. repairing the cracks is an easy DIY task for most homeowners. All you need to do is to follow these suggestions carefully. By following the suggestions you will save a lot of your time and effort and save your sidewalk from further deterioration.

Enlarge the cracks in concrete to repair it. You can use a chisel and hammer to widen the crack along its length. Without enlarging the crack, it will not be possible to repair the crack properly.
Make the crack wider at the bottom than the top. This will help in joining new concrete with sidewalk.
Depending upon the size and total length of the crack, you can decide on the undercutting depth. Usually, you will need to undercut the crack up to a depth of at least one inch.
Clean the enlarged crack with the help of a brush. Insure that no loose material is left in the crack.
Use compressed air to get rid of dust in the crack. If compressed air is not available, clean the crack thoroughly with the help of a brush.
Use a good quality brush to clean the crack and allow time for it to dry.
Insure that the patch area is moist if using cement for the repairs. There should be a little moisture on the crack when the cement is applied. However, if you are using a cement adhesive, eliminate all moisture so the adhesive will adhere to the concrete.
Prepare a concrete mixture by adding 2 and 1/2 parts of sand to 1 part of Portland cement. You may need to increase the ratio of cement for heavier concrete jobs.
Completely fill the crack with the concrete mixture and tamp it. Use a metal trowel to make the surface of the crack smooth.

Let the patch dry for a few hours and keep it covered for a few days. Drop water on the patch everyday so that concrete will gains strength.

That is all there is to it.

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