For asphalt driveways, choose a water-based acrylic filler/sealer. You can expect to cover 300 to 500 sq. ft. per five gallons of sealer, depending on the general condition of the driveway and if it has been sealed previously. For best results, use filler/sealers that fill cracks up to 1/8" wide and look for crack fillers that have rubberized asphalt emulsion. For cracks less than 1/8", use crack filler in pourable squeeze bottles. Squeeze the liquid into the crack filling the crack completely.
For cracks up to ½", use crack filler packaged in no-mess cartridges for a caulking gun or in pourable squeeze bottles. Squeeze the caulking gun trigger steadily as you pull the tip along the crack. If using pourable filler, fill the crack and smooth away excess with a putty knife. Be sure to keep the filler in the crack, not on the driveway surface.
For cracks ½" to 2" wide, fill the crack with non-porous foam backer rod material before applying crack filler.
For potholes or cracks wider than 2", you'll need to do a little more repair. Shovel packaged cold-patch blacktop into the well-cleaned hole, and then use an iron rake to level the patch. Use a cold chisel and a hand-drilling hammer to undercut the edges so the hole is wider at the bottom than it is at the driveway surface. This will lock in the patch once it has been compacted.
Clean tools immediately after use with warm soapy water. You don't want the filler to set on your tools for good.
Press down the material as best as you can with a tamper or the end of a 2 x 4 board, adding more material as you go, until the hole is slightly overfilled. Then place a piece of scrap plywood over the patch and drive your car back and forth across it to further compact it.
Once the cracks are filled, it's time to seal the asphalt. First, be sure that your patches have cured for at least one day, if not two. Before you start, mix sealant well and once or twice during the process. After masking adjoining areas, mist the driveway with water. Then pour a 1'-wide ribbon of sealant across the driveway. Push and pull the sealant with the squeegee side of a brush applicator to spread it until you've covered an area that's about 3' or 4' wide. Repeat this process until you've covered the entire driveway. You can also go over the surface with a paint roller on an extension pole to even out the coverage.
Using the brush side of the applicator, pull the sealant toward you and apply enough pressure to remove all excess sealant. Continue down the driveway. Two thin coats are better than one thick coat. Allow the first coat to dry between 4 to 12 hours before applying the second. Block the end of the driveway to keep cars off until it is completely dry — at least 24 to 36 hours.
You can use silica sand additive to make coatings less slippery when wet.
To fill hairline concrete cracks, you can usually use a patching compound to make the repair. First apply a concrete bonding adhesive or primer/additive to create the best bond possible between the old surface and the patching material. Use an old or inexpensive paintbrush to work the liquid into the surface. Wash the brush immediately after use with soap and water or discard it.
Use gloves, goggles and a dust mask when preparing the driveway or handling cement products.
The primer will stain so avoid getting it on any adjacent surfaces. Wash it off promptly if it does get on any other surfaces.
Use a putty knife or trowel to apply a vinyl patching compound in multiple layers as directed by the manufacturer. Mix only the amount of patching you'll need for each layer. Press it firmly to force the initial layer into all nooks and crannies and allow drying time between layers.
You can also patch thin cracks with a cement mixture. In a small bucket, mix one part cement and three parts sand with enough water to make a stiff paste. In a separate container, mix a small amount of cement with more water — enough to make a cement paint.
If you can, paint the inside of the crack with the thinner cement mixture. This will act like a primer. Then take the paste mixture and pack it firmly into the crack with a putty knife or trowel. Level the mixture with a straight-edged concrete-finishing trowel. Let the patch sit undisturbed for about an hour, then go over the entire surface with a float or trowel in a circular motion, blending it well with the surrounding surface.
When applying the patch, make sure you cut deeply into the mixture with your trowel to remove any air pockets.
To patch large cracks (more than 1/8'' wide and 1/2'' deep), use foam backer rods. Sold in a variety of lengths and diameters, foam backer rods are great for supporting a patch and preventing it from sinking into any cracks as it dries and ages. Use a putty knife to force the flexible rod into the crack, placing it about 1/4'' below the surface. Now you can patch the area as you would with a small crack. After smoothing the patch with a trowel, let it set for a couple of hours. Then cover it with a sheet of plastic, weighing the plastic down at the edges with bricks or rocks. Keep the area covered for an entire week, making sure to mist it with a little water each day to keep it slightly moist.
Alright! You're done! Your driveway is now structurally sound and looking like new.