The U.S. Department of Transportation recommends rubberized crack sealing as a cost effective way to prolong the life of asphalt roadways/parking lots. For example, on average it costs five dollars to seal a 10-ft crack that is a 1/2″ wide and 1/2″ deep. If this same crack is left unsealed, water will penetrate and erode the sub-base, causing the surrounding asphalt to fail.
This failure is called “Alligatoring”. Depending on the size of the job, removing and replacing the deteriorated asphalt around the 10-ft crack costs $50 to $80.
In addition there are other intangible costs to cities or businesses, such as down time due to rehabilitation projects. There are additional costs assessed from poor image, which contributes to negative customer perceptions.
Note: According to the federal Strategic Highway Research Program (SHRP), every $1.00 spent on crack sealing, saves $4.00 in rehabilitation cost.
Minor damage to your concrete driveway should be repaired quickly to avoid major problems in the future. Cracks in your driveway provide access for water that can freeze and expand the cracks. Freeze/thaw damage can lead to costly repairs or even the complete replacement of your driveway.
Clean The Area Thoroughly
Remove all loose debris, including dirt, sand and chunks of concrete. Use a broom or hand brush to sweep the area down. Hose off the crack using a jet-type spray attachment. If the crack is grease or oil stained, clean the area with detergent and rinse thoroughly. Allow the cracked area to dry completely before proceeding.
Hairline Cracks (Quarter Inch or Less)
After cleaning, fill the crack with a concrete sealer. Concrete sealer is available at most home centers and comes in a tube similar to caulk. Once you’ve applied the concrete sealer, smooth it out with a scraper. Allow the concrete sealer to dry and inspect the crack. If the sealer has shrunk or not completely filled the crack, reapply and smooth as needed.
Larger Cracks (Quarter Inch to Half an Inch)
Slightly larger cracks will require the use of pre-mixed mortar or a grout made of water and Portland cement (only add enough water to create a thick paste). Apply the mortar or grout to the cleaned crack and smooth it with a scraper. After it’s dried, apply another coat if shrinking occurs.
Large Cracks or Holes (Greater Than Half an Inch)
Cracks larger than half an inch should be undercut using a hammer and chisel. Undercutting means to make the bottom of the crack wider than the top. Undercutting will add to the strength of the repair. Be sure to wear gloves and when undercutting the crack.
After undercutting the crack, clean is thoroughly. Apply premixed concrete to the crack, using the manufacturer’s instructions. Allow the concrete to set for one hour before smoothing with a trowel. Drape a wet cloth over the concrete patch and keep it damp for 2 or 3 days to allow the concrete to cure completely.
Cracking in asphalt/concrete is a phenomenon that pavement design and maintenance engineers have had to contend with for years. Fatigue cracking is the principal consideration in pavement maintenance. Cracks are inevitable, and neglect leads to accelerated cracking and/or potholing, further reducing pavement life and serviceability.
The problem of cracks is handled in many ways, ranging from pavement maintenance activities, such as surface treatments (seal coating or road slurry and hot rubberized crack sealing) to full-scale pavement rehabilitation projects, such as resurfacing. Maintenance departments/Property management companies bear most of the burden of dealing with cracks. Agencies with sufficient funding are often responsible for adding a few more years of serviceable life to deteriorated pavements, through preventative or routine maintenance, or both.
One of the more common options exercised by city or state maintenance departments is crack sealing. This operation has been conducted for many years, generally on a routine basis. However, only in the last two decades has its potential benefit as a preventive maintenance tool been realized.
Hot applied rubberized crack sealants should not be confused with cold applied Latex crack fillers that are non-elastic. Due to their non-elastic nature, as seasonal temperatures change, causing the asphalt to expand and contract, these cold applied fillers will re-crack prematurely causing further asphalt deterioration.
Cracks are cleaned of all dirt, sand and debris using no less than a 185 cfm compressor at 110 psi. This will facilitate adhesion of rubberized material to the asphalt. All vegetation must be removed prior to application of material. It is recommended that a weed sterile and be applied one week before removal to prevent vegetation re-growth.
All moisture must be removed from cracks to allow proper adhesion of rubberized material. A specialized hot air head lance is required for this purpose. The heat lance accompanied by a 185 cfm compressor produces an air stream velocity of 3,000 ft/sec. and an air temperature of 33,000 degrees Fahrenheit.
Grinding provides for better adhesion of rubberized material to the asphalt crack’s side wall. It also creates a reservoir for rubberized sealants. This reservoir of material will last longer and make for a better quality seal. Cracks 1/8″ to 3/8″ should be ground to a minimum of 1/2″ wide by 1/2″ deep.
RW rubberized sealants should be applied in prepared cracks at a temperature of approximately 380 degrees Fahrenheit.