If you have asphalt roads, some of them surely have some cracks. To the extent these are environmental, they come with age and that’s fine. If they are because of compromises in the mix or poor laydown, that’s a topic for another day. Regardless, cracks in your asphalt are not your friend and as they let water into the subbase, they just keep costing you more and more. So, hopefully the answer is yes, you do plan to do some crack sealing this spring.
In the past, we introduced the Pavement Preservation & Recycling Alliance (PPRA) Treatment Toolbox, available for free as an online resource for your pavement preservation planning. A great tool in their Treatment Resource Center is rather in-depth guidance on crack sealing for pavements.
Crack sealing is one of the most cost-effective means of extending the life of pavements and yet it is sadly underutilized in many local agencies. The best designed and constructed pavements will develop cracks. In asphalt pavements, environmental cracks that develop in the first few years allow water to infiltrate under the asphalt instead of shedding off as intended by the cross slope. The water under the pavement reduces the structural strength of the supporting materials and the asphalt flexes and pumps under tire loads, leading to more extensive distresses, such as settlement, alligator cracking, and base failure. Crack sealing early on recognizes that pavements need to relieve internal stresses but forms a barrier to water that wants to infiltrate and damage the pavement cross section.
The PPRA site provides succinct guidance on a range of issues related to crack sealing, including expectations, best practices, site and material selection, site preparation, weather conditions for application, and quality assurance tools.
Again, too many local agencies don’t use or rarely use crack sealing and the result is that their pavements develop advancing distresses much earlier in the pavement life than they should. Some agencies worry that the contractor will take advantage of them by sealing every little crack they can find (a worry when paying by the linear foot or product usage) or by overlooking cracks (a worry when paying by the square yard), but the PPRA site can provide guidance on how to manage your contractor and avoid those excesses.
Other agencies may have had poor experience with crack sealing, and it is helpful to go back and evaluate if the timing was right for sealing, if the surface was properly prepared, or if the correct material was used. The PPRA site has guidance on those topics as well. This was on one of our vendor’s minds at the Roadway Management Conference last October. While the pavement was a little wet from rain that morning and the temperature was borderline, we and they both wanted to demonstrate crack seal to our 200 or so attendees. So, they spent an inordinate amount of time cleaning and drying the cracks prior to the afternoon demonstration.
It worked out fine and it was an example of the kind of logistical planning needed for successful crack sealing. But in practice, you can get out ahead of cold temperatures and select a day when the pavement and cracks are already dry, so the time pressure of a conference setting was unusual.
Still other agencies worry that they don’t know enough about crack sealing and the materials used to properly oversee the contracted work. That is exactly why the PPRA site can be a helpful tool, because being a good consumer is Job #2 (right behind safety) for local agency personnel and once you understand the fundamentals of crack sealing techniques and materials, you can be a good consumer and preserve your pavements.
In short, hand wringing is silly and most agencies can manage crack sealing with a lot of success. So, take a little time, browse the PPRA crack sealing site, and start planning which of your pavements can benefit from crack sealing this spring. The Delaware T2/LTAP Center’s Municipal Engineering Circuit Rider is intended to provide technical assistance and training to local agencies and so if you have pavement management questions or other transportation issues, contact Matt Carter at matheu@udel.edu or (302) 831-7236.
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