If the cracks are small, what I would consider hairline cracks and these wouldn’t be any bigger than the tip of a regular ink pen. I wouldn’t worry about these until they get larger, even if they get larger, it might not become a problem. Some small cracks will remain small for an extremely long time.Do you want to learn more?see here
How do you repair cracks that you can slide a penny into? If the crack is larger than 1/2″ or even if one side of the broken driveway is starting to sink or rise, don’t bother filling them in, you’ve got some soil or concrete problems. I would recommend that you replace these damaged areas, rather than filling them in with a good sealant.
Use a broom or a brush to remove any dirt or debris that is surrounding the crack or even inside of the crack. Then I would recommend using a vacuum cleaner to get as much of the debris out of the crack as possible. If you have time and really want the crack clean, spray the area down with water and wait 24 hours to apply your sealant.
Make sure that the concrete is clean and there isn’t any film of dirt, in the crack. If there is, make sure that you use a stiff brush with soap and water to remove as much of it as you can, from the inside of the crack.
After the concrete crack has been cleaned, you can fill the cracks, using a concrete sealant for crack repairs. This can be purchased at almost any home improvement center or lumber yard.
Let this area sit for 24 hours, or follow the recommended manufacturer time for curing or drying. That’s it, you’re done and if the crack continues to expand, you can find yourself doing it again, sometime in the future. Hopefully it won’t be in the near future.