Over time, road surfaces develop cracks due to wear, traffic, environmental conditions and other causes. If the cracks are left untreated, the cracks can develop into larger cracks or potholes, which become more expensive and time-consuming to repair. Moreover, potholes create unpleasant driving surfaces, and in some cases can be hazardous.
Conventionally, cracks are treated and filled with a hot or cold pour sealing agent, usually a hot sealing agent, applied to fill the crack. Typically, in order to create a hot, pourable sealing agent, a large portable reservoir or kettle is maintained at a high temperature, for example 350-425 degrees, in order to raise and maintain the temperature of the sealing agent at a sufficient level. Maintaining the high temperature of the portable reservoir requires the consumption of energy, and when one or more road crews are repairing cracks in roads throughout a town or city for full day shifts, the energy consumption required to maintain the sealing agent at temperature can be significant.
Moreover, a typical conventional hot pourable sealing agent can require hours in order to properly cure, dry and seal the crack in a road. During this time, traffic must be rerouted so as to prevent cars, trucks and other traffic from traveling over the repaired portion of the road, while it cures and dries.
The primary technique traditionally used heretofore for repairing cracks and other distressed pavement areas has been to fill the distressed areas with hot asphalt. In addition to the shortcomings already listed above, other problems associated with hot pour asphalt fillers include: the emission of volatile organic compounds; a lack of adhesion to the sidewalls of the crack or other distressed area; inadequate structural integrity and load-bearing capability; short service life; a lack of skid resistance; lengthy curing times; discoloration; and tracking and adhesive loss on the pavement.
The hot pour asphalt compositions used heretofore for filling cracks and other distressed pavement areas have included some fillers and polymers which have improved the properties of the composition to some extent. However, it does not appear that hot pour asphalt compositions containing aggregates or other such additives capable of providing significant structural support and load-bearing capacity have been successfully formulated and used for filling pavement cracks. The hot asphalt composition has simply been placed in cartons, cooled, and then reheated at the pavement site for pouring into the pavement cracks.
As mentioned above, as an alternative to hot asphalt filling, another technique used for repairing cracks in pavement has been to fill the cracks with a cold pour asphalt emulsion. However, in addition to having all of the same problems and shortcomings as listed above for hot pour asphalt, the existing cold-pour compositions and techniques are particularly noted for bad quality and a lack of bonding to the existing pavement. The cold pour emulsion materials used heretofore have been much too soft and, as with the hot pour materials, have lacked any aggregate framework to provide load-bearing strength. Moreover, as compared to hot asphalt, any effort to add aggregate materials to cold pour asphalt emulsions prior to use for road repair would be particularly problematic because the contact between the aggregate material and the asphalt emulsion causes the emulsion to break and begin to set.
As is known in the art, cold pour asphalt emulsion compositions are generally classified as anionic or cationic and can be slow, medium, or fast setting. Although anionic cold-pour asphalt emulsions have been used for filling pavement cracks with less than desirable results, it is not believed that cationic compositions have not been adequately developed for crack repair or pothole applications. The anionic emulsions are much more stable and have heretofore been understood to create more usable mixtures.
During road paving operations, in order to provide structural support for asphalt road materials, large pugmill paving mixers are used for blending aggregate fillers with the hot asphalt or with cationic quick-set asphalt emulsions prior to laying a broad swath of the material to form a road layer. Hot mix asphalt paving requires, among other things, that (a) liquid asphalt and aggregate be mixed at high temperature in a hot mix asphalt plant and then (b) the hot mixture be carried to the paving site by a series of dump trucks and the pavement layer be formed using a placement device (or screed) and various compaction rollers. The machines used for cold pour emulsion paving are slurry seal pavers. The large size and configuration of these paving machines are suited for asphalt surfacing over the cross section of a road.
However, in addition to the fact that aggregate materials have not been used in asphalt compositions for crack filling operations, the hot asphalt mix plants and slurry seal pavers used in the art for road paving operations are entirely unsuited for crack filling operations. In one respect, the design, size, capacity, and bulky construction of these machines are much too large and ill configured for crack filling operations. Hot mix asphalt plants are centrally located so that the hot mix product must be carried from the plant via dump trucks. Slurry seal pavers are large truck-mounted plants.
Also, slurry seal pavers, for example, are specialized, high capacity paving systems which are designed and configured solely to provide proper component sequencing for the formation of highly aqueous compositions suitable for road paving. These compositions are not suited for crack filling operations because, in contrast to an exposed layer of pavement, deep cracks have very limited atmospheric exposure, which would substantially prevent an aqueous system from breaking, setting, and curing adequately. And, if these compositions were not adequately hydrated for properly wetting the side walls and aggregate, the system would fail.
Moreover, even if a slurry seal paver were capable of forming a workable crack repair composition, the system and machinery which would be required to (a) quickly reroute a relatively small stream of material from the large paver from one distressed pavement location to the next and then (b) precisely deliver the material into a crack would, if capable of construction, be costly and complex.
A need, therefore, exists for an improved road surface composition, process, and apparatus which will: allow rapid repairs with a quick setting time; minimize road downtime; provide significantly greater load bearing capability, skid resistance, and service life; reduce costs and energy requirements; and reduce emissions. As recognized by the present inventors, what is needed is a cold pour composition, process, and applicator apparatus for sealing road cracks, potholes, or other distressed road areas in need of repair.
In addition, a need exists for an improved aggregate filler material, and improved asphalt mixtures containing such aggregate materials, which will provide significantly improved load-bearing capability, service life, and lateral load distribution properties.