By Priscilla Tsai And

By Priscilla Tsai and

Contributions by Brian Price

Any asphalt-paved surface is subject to cracking at some point during the duration of its life. Cracks occur when stress is built up in the surface layer that exceeds the strength of the pavement causing fissures or cracks.Cracks come in many sizes and shapes – categories of cracks include fatigue cracks, longitudinal cracks, transverse cracks, block cracks, reflection cracks, and edge cracks. These cracks should be treated in order to preserve the lifespan of the paved surface. The purpose of crack treatment is to protect underlying pavement from water infiltration, destructive impurities and incompressibles; to maintain pavement integrity and strength; and to improve ride quality smoothness and reduce pavement deterioration.

To receive the most benefit from crack treatment, treat the pavement early when the cracks first appear in order to preserve and extend the life of the pavement for the maximum amount of time possible.

The approach to crack treatment is different for different customer types. For example, home owners or very small businesses may receive benefit using cold-pour crack treatment, which does not require equipment to install. For more longevity, homeowners and small businesses may advance to direct-fire hot-applied sealants that require minimal equipment to install. Larger businesses, airports, roads and highways though will require hot-applied crack treatment and more equipment to install.

Determining crack type

In order to properly repair a crack, first assess the pavement condition to understand the amount and severity of the distress. This will help you determine if treating the crack will provide benefit to the pavement. Some pavements are in too poor of a condition to benefit from crack treatment. Most pavements though will be able to be treated and receive years of benefit.

Next determine the movement of the cracks in the pavement. Pavement is flexible and does move. Some causes of pavement movement include changes in the temperature due to sun and climate, traffic moving over the surface and movement in the soil. Cracks can be separated into categories of “working” and “non-working” cracks. According to the Federal Highway Administration’s definition, working cracks are cracks that move greater than or equal ⅛ inch (3 mm) annually. Non-working cracks move less than ⅛ inch (3 mm) annually[BP1]. While all cracks have the potential to be working cracks, generally transverse or longitudinal cracks are considered working cracks.

Next After determining crack movement, determine the service life you desire for your crack treatment. If your customer desires a long service life such as 5-7five to seven years or longer, you will need to rout or saw the cracks and use high-performance sealer or filler. If a couple of years of service life is adequate, you don’t need to rout or saw the cracks as long as you continue to use a high-performance sealant or filler. Routing or sawing is the process of using a machine to clean the crack. By routing or sawing the crack you will remove the dirt and debris, remove the oxidized and deteriorated asphalt near the crack, and create a new, clean reservoir and a strong surface to bond with the crack treatment that can double the service life of the treatment. The rotary-impact router is the most recommended and commonly used machine because it has the highest production -rate, the lowest cost of operation, good maneuverability, and causes minimal additional damage to the pavement when using carbide-tipped router bits. New innovations in routing such as self-propelled machines with dust control make routing easier and cleaner than at any time previously in historyever before.[BP2]

Now that you know the pavement condition, the movement of the cracks, the service life you desire, and whether you are placing the material in a reservoir or capping the crack, it is time to select the crack treatment.

Crack Treatment

So what's the difference between sealing and filling? Generally working cracks are sealed with high-performance crack sealant and non-working cracks are filled with high-performance crack filler. Sometimes it isn't practical to have two separate machines placing two separate products into cracks, so in those cases high-performance sealant is used on both working and non-working cracks.

High-performance crack sealant and fillers contain many ingredients like asphalt, rubber, oils, fillers, fibers and special polymers. Special polymers can be the most expensive ingredient in the sealant or filler. Generally, high-performance sealants contain more polymers and are more expensive. High-performance fillers contain less polymers and more inert fillers so they are less expensive. High-performance fillers can be 5 - 15% less expensive than the high-performance sealers specifically designed to fill the same crack. Not all sealants and fillers are the same. For example, oil and sand areis used as a fillers and areis less expensive than high-performance filler, but it filler with oil and sand will not provide the same performance in terms of flexibility, durability and longevity that high-performance fillers can provide.

Selecting the right sealant or filler is important to the outcome of your project. Eighty percent of the cost of placing sealant or filler is the cost of labor, so if long service life is desired, then selecting a sealant or filler to last many years is an important decision in order to get the most return-on-investment. Continually filling the same crack year-after-year is not cost-effective and is inefficient. Before selecting the final sealant or filler you will want to know the climate (low and high temperature extremes), the type of surface (highways, residential streets, parking lots, airports), and the amount and type of traffic (low, medium, high). These factors can affect the service life of the sealant or filler. If you are unsure as to whether you are using the right treatment for the application, contact your high-performance sealant or filler manufacturer or distributor. In some situations manufacturers like Crafco will design and manufacture a product to specifically meet your customer's needs.

Materials

There are a variety of products available. In general there are two categories: hot-applied and cold-pour sealants. While we have talked extensively about hot-applied sealants, cold-pour sealants are an alternative. Cold-pour sealants provide protection for up to 1-year on roads and highways. Cold-pour sealants have advantages of not requiring heating or special equipment, can bebeing able to be applied to moist or damp cracks (although it will take longer to cure), and penetrating the cold-pour sealant will penetrate into the crack easily without any need for routing (however the crack does needs to be clean to insure adherence to the crack). Cold-pour sealants tend to be significantly more expensive when comparing a gallon of cold-pour to a gallon of hot-applied sealant, but may be cost effective for small jobs because they don’t require extra equipment. While cold-pour sealants fill an important customer need within the market, hot-applied materials are superior in performance as proven by multiple independent studies.[BP3]So what’s the difference between sealing and filling? Filling is the simple process of using sealer material to fill in any voids in the crack. It’s usually used as a temporary solution between scheduled major maintenance work. Driveway cracks are usually filled because it’s an easy process using cold pour material and it doesn’t require any equipment. Because driveways are smaller worksites and are serviced for sealcoating more often than say, a large parking lot, any cracks that have reopened can be quickly touched up every few years with sealcoating is re-applied.[BP4] Sealing is more popular on parking lot areas because it offers a more permanent solution that will last between sealcoating jobs which are typically performed much less often for parking lots than driveways. [BP5]Sealing is a more thorough and involved job than filling and requires special equipment. When sealing, cracks need to be cleaned of grass, dirt, weeds, and other debris, using high pressure water, compressed air, or flame. Tools such as diggers and brushes may be required to clean the crack well and create a uniform depth. Once the crack is cleaned, the sides of the crack walls need to be cleaned with a torch or brush to contribute to proper adhesion of sealer material. [BP6], according to various Department of Transportation reports.

Methods[BP7]

When using cold-pour sealant to fill a crack at a home or small business, a contractor only needs cold-pour filler material – no melting equipment is necessary. For cracks up to ½ inch wide, cold pour is recommended. For cracks ½ to 1-½ inch wide, trowelable type filler is recommended. The thicker trowelable material won’t run through a crack and fills wider cracks better. Each manufacturer carries its own brand of fill, says Browne.

T

To fill a crack, a contractor only needs filler material - no melting equipment is necessary. For cracks up to ½ inch wide, cold pour is recommended. For cracks ½ to 1-½ inch wide, trowelable type filler is recommended. The thicker trowelable material won’t run through a crack and fills wider cracks better. Each manufacturer carries their own brand of fill and a contractor’s selection really depends on preference and availability, says Browne. “They are all comparable products.”[BP8]

When using hot-applied sealant the equipment and material needed includes a melter and hot-applied sealantcrackseal. The two types of melters available on the market are direct fire melter machines and oil jacketed melter machines. While both can melt down hot rubberized crack sealant, the way they heat the material differs. Direct fire melters use direct flame to heatand melt down crack sealant, while oil jacketed melters use indirect heat to melt sealant by firing into a chamber filled with oil, which in turn heats the material. Both do a good job melting crack sealant, but due to the cheaper price point, Browne says he sells more direct fire melters to everyday contractors looking to do a few jobs here and there. For those looking to do a large quantity of cracksealing though in large areas though, Browne recommends the oil jacketed melter because it can melt more material at once, and the material for the melters is less expensive than that for direct fire melters. The cost per pound for large jobs is less, allowing contractors to save on material costs.[BP9]

New on the market this year in the crack sealing industry is the meltable packaging for blocks of crack sealant. The no-box/PLEXI-melt [BP10]packaging for a few years now, Browne reports that it’s the first season that the products have come onto the markethas been on the market for a few years now. Crafco launched PLEXI-melt for its Crafco and Deery brand of products in January 2012 after several years in research and development.The exciting new packaging for sealantis a time-saver – it can be thrown into the melter along with the sealant, eliminating the need for unboxing blocks of sealant, and the flatter design allows for faster melting.[BP11]The no-box packaging also benefits the environment – there is less environmental waste because the entire package is placed in the melter, and less fuel is used in the transportation of the materials to the job site since it is the lightest weight packaging available (3 oz.) that is weather and water resistant.

“With the meltable packaging, there are no more boxes laying around that you have to get rid of. Instead of taking it out of a box, you can throw it directly into the machine,” explains Browne. “Though it’s a bit more expensive per pound, it’s for the convenience. People are spending a lot less time heating the material up, which is where the biggest cost is – the guys out there doing the work. Overall it saves contractors a lot of money. If you are spending an hour or two less on the job, it’s all worth it.”

NAC Supply currently carries two types of sealant with meltable packaging: Deery’s PLEXI-melt Meltable Packaging Option for Superstretch & PLS, and Right Pointe’s NoBox Meltable Packaging Option for Direct Fire & 3405. “Both are good products and selection depends on personal preference,” says Browne. While the benefits of the meltable packaging are good, Browne still plans on carrying the boxed sealant for those who still prefer the original packaging.

To learn more about crack filling and sealing, please contact:

Brian Price

Crafco, Inc.

800-528-8242
Dan Browne
NAC Supply, Inc.

877-767-4622

[BP1]A more widely acceptable and credible source is FHWA. Smith, K.L., and A.R. Romine. 1999a. Materials and Procedures for Sealing and Filling Cracks in Asphalt-Surfaced Pavements. FHWA-RD-99-147. SHRP-H-348 Asphalt Pavement Repair Manuals of Practice.

[BP2]1Smith, K.L., and A.R. Romine. 1999a. Materials and Procedures for Sealing and Filling Cracks in Asphalt-Surfaced Pavements. FHWA-RD-99-147. SHRP-H-348 Asphalt Pavement Repair Manuals of Practice. Strategic Highway Research Program, Federal Highway Administration, Washington, D.C.

2Smith, K.L., and A.R. Romine. 1999b. LTP P Pavement Maintenance Materials: SHRP Crack Treatment Experiment, Final Report. FHWA-RD-99-143. Federal Highway Administration, Washington, D.C.

[BP3]”Evaluation of Pavement Crack Treatments – Literature Review”, Zinke, Scott, Hogge, Brian, O’Brien, Chris and Mahoney, James, Connecticut Department of Transportation Report Number CT-2241-F-05-6, July 2005

”Field Performance of Hot and Cold Pour Crack Sealing Treatements on Asphalt Surfaced Pavement.” Yildirim-Y; Qatan-A; Kennedy-TW, Texas Department of Transportation, Federal Highway Administration, University of Texas at Austin Center for Transportation Research, Report Number: FHWA/TX-034061-2, 2003

”Performance Comparisons of Hot Rubber Crack Sealants to Emulsified Asphalt Crack Sealants.” Draft Final Report, Yildirim-Y, Korkmaz-A, Prozzi-J. Texas Department of Transportation, Federal Highway Administration, University of Texas at Austing Center for Transportation Research, Report Number: 4061-F, October 2004

”A Study on Hot-pour and Cold-pour Joint Sealer, Internal Evaluation.” Bednar, Andrew and Boardman, Jonathan. Connectivut Department of Transportation, Office Research and Materials. Division of Materials Testing, 2003.

Connecticut Department of Transporation memo from James Sime to Louis R. Malerba, July 8, 1997

”Field Manual for Crack Sealing in Asphalt Pavements.” Research Project 0-4061-P3, Comparison of Hot-Poured Crack Sealant to Emulsified Asphalt Crack Sealant. Center For Transportation Research The University of Texas At Austin. January 2006.

[BP4]This is pulling in sealcoating which could be its own topic. I would remove it because it isn’t critical to the story.

[BP5] High-performance fillers can last as long as high-performance sealers. The reason being, is because fillers are not put in working cracks. Fillers have much of the same ingredients as sealers, just not the same ratio because they are designed to be placed in cracks that are not working as hard as working cracks.

[BP6]We don’t agree with this statement. The procedures to install crack seal or crack fill are the same for a quality job. The only difference is the material you put in the crack.

[BP7]More time could be spent on application method to include:

-Optimal time to crack treat

-Preparation for crack treatment (cleaning is vital to the performance of the job)

-Cold vs hot applied treatment application differences

-Best treatment configurations (overband, flush-fill, simple band-aid

-Recommendations for routed/sawn reservoir size

-What to look for when installing sealants

A whole article could be written on application, making this part 1 of a 2 part article if you desire.

[BP8]I don’t agree that all products are comparable. These two articles are ‘pivotal’ independent studies showing there are differences between products, and there are others as provided in this document that I sent you, and many more I haven’t sent you.

1Smith, K.L., and A.R. Romine. 1999a. Materials and Procedures for Sealing and Filling Cracks in Asphalt-Surfaced Pavements. FHWA-RD-99-147. SHRP-H-348 Asphalt Pavement Repair Manuals of Practice. Strategic Highway Research Program, Federal Highway Administration, Washington, D.C.

2Smith, K.L., and A.R. Romine. 1999b. LTPP Pavement Maintenance Materials: SHRP Crack Treatment Experiment, Final Report. FHWA-RD-99-143. Federal Highway Administration, Washington, D.C.

[BP9]I would eliminate these two paragraphs and continue with the packaging. This way the article focused on crack sealing and sealant/filler. The methods for application and equipment would be take more time and attention.