Asphalt maintenance is one facet of property management that is overlooked on a regular basis. If a property owner has a hole in their parking lot, it is not treated with the same urgency that a hole in their roof would require. Unfortunately, this neglect of their asphalt leads to more costly repairs in the future that could have been avoided if the property owner would have followed a preventative maintenance plan for their asphalt.
What is asphalt maintenance? Asphalt maintenance consists of protecting asphalt by employing the following methods (asphalt seal coating, crack repair and asphalt repair) to prevent damage to the existing asphalt.
So why should a property owner have their asphalt seal coated? From the very first moment that asphalt is installed, it starts a deterioration process. The asphalt is diminished when the binder that holds all of the aggregate (stone) together begins to oxide from sunlight, water, and other external conditions. Through the seal coating process, the asphaltic binder is now protected from the aforementioned external conditions. An additional benefit from asphalt seal coating is that the asphalt is now protected from the damaging effects from gasoline, oil, and de-icing salts. The most obvious benefit from asphalt seal coating is the restoration of the original color of the asphalt. The asphalt regains that new appearance for a fraction of the original cost.
Asphalt seal coating is a process in which coal tar emulsion or asphalt emulsion is sprayed or brushed on the asphalt surface. The seal coat material should be applied in two coats in general areas and three coats in the high traffic areas, such as drive lanes.
There is much debate as to what is the best application method for the seal coat material. There is a predominant mindset amongst "old school" seal coaters that brushing the seal coat material is the only way to go. However, there are some shortcomings from the brushing technique. By brushing the seal coat material the natural indentations of the asphalt are filled in and the asphalt loses its traction. Also, contrary to popular belief thicker is not better when applying the seal coat material. The Seal coat material should be applied at .17 gal/sq. yd. and should never exceed .51 gal/sq. yd. total.
With the shortcomings of brushing the seal coat material being stated, there is a better alternative. That alternative is spraying the seal coat material. This method allows the seal coat material to be applied evenly without filling the natural grooves of the asphalt. If a contractor states that they brush exclusively, take caution in dealing with these companies. Many times these companies have not invested in updated equipment, which will prevent them from completing the bigger seal coating jobs.
Another aspect of seal coating that is overlooked by customers is the mixture of the seal coat material itself. The material is should be mixed at 25 to 35 gallons of water per 100 gallons of concentrated sealer. Also, the seal coat material should be enhanced with 2-5 pounds of sand per every gallon of sealer. The sand is used to restore traction to the surface after the asphalt has been treated. When creating work specifications make sure to include the amount of desired sand required per gallon of sealer. The smoother the existing surface or the higher the traffic volume will require higher volumes of sand in the seal coat material.
In addition to asphalt seal coating, crack repair is vital to properly caring for asphalt. Due to the settling of the ground, poor base design and asphalt oxidation asphalt will crack. When the asphalt cracks it is exposed to water damage. Water penetrates the cracks and gravity pulls it into the sub-base (stones) which deteriorates that supportive structure. This deterioration leads to asphalt depressions, potholes and further cracking. Also, in the winter when water expands in the cracks via the freezing process, the cracks widen over time.
Hot tar is applied to the cracks to prevent water penetration. Hot tar is melted to 375 degrees and poured into the cracks. To finish the crack repair process the hot tar is squeezed into the crack to create a 4-inch band. All debris should be removed from the cracks before treatment. Crack repair is a temporary fix and does not replace the need to actually replace the asphalt. However, crack repair is much more cost effective than actual asphalt replacement.
It is said that if 30% or more of asphalt is deteriorated, it is more cost effective to replace it. With that being said, the majority of property owners choose to replace certain sections at a time. One thing to keep in mind is that if an area of asphalt needs replaced because it was sinking, there is definitely a problem with the sub-base and that should be replaced as well.
If the asphalt needs to be replaced there are two methods for replacement. The conventional method is to saw cut the area and replace the asphalt and seal the seams with hot tar. Another modern method consists of using an Infrared Heater to heat the existing asphalt, then additional asphalt is added and the area is compacted. The benefits of using an Infrared heater is that the fix is a seamless fix that will no longer allow water penetration. The major fall back with using infrared is that if there is an existing sub-base problem, the asphalt will not be properly repaired if it is only re-heated and not actually removed to replace the underlying stone. In the right conditions, Infrared treatments to asphalt add extra benefits to the property owner because of the final aspect of seamless repair.
The bottom line is that property managers should incorporate an effective asphalt maintenance strategy into their overall preventative maintenance strategy. The benefits of asphalt seal coating, crack repair and asphalt replacement will pay dividends in the future through the avoidance of costly new asphalt. One last point, the asphalt maintenance and pavement marking industry have a wide fluctuation in the quality of contractors, so always do your due diligence in the selection process.
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