If you do anything to your asphalt pavement this fall, it should be crack repair. Here’s why. Asphalt pavement is a flexible material that expands and contracts due to temperature fluctuations and shifts in response to traffic loads. Since it is always moving to some degree, filling or sealing cracks is critical to preserve pavement.
And, fall is the ideal season to perform crack repair because the pavement is midway between its minimum and maximum movement. Treating cracks at this time of year enables the sealant to fill and seal cracks more effectively.
Crack Filling vs. Crack Sealing
Crack filling is a process by which cold-pour material is applied to fill the void in a crack. This procedure is ideal for smaller or isolated areas of cracking. While effective in reducing water intrusion, crack filling does not preserve the pavement as long as crack sealing. The reason is because the filler material does not move with the pavement as it expands and contracts and it does not have high or low temperature properties.
On the other hand, crack sealant is specifically engineered with specialized materials that allow it to remain flexible at low temperatures so it doesn’t crack or split open, and it remains stable at higher temperatures so that it doesn’t track or bleed on the pavement.
The Right Product
There are a lot of crack sealants to choose from; they range in thicknesses as well as different viscosities. They also come in ultra-soft to very hard material. In general, parking lots typically require a stiffer product while roadways require a soft product. A higher softening point reduces sticking or tracking in hotter regions, while a crack sealant with a lower softening point would likely be adequate in colder climates.
Based on their ease of use and cost-effectiveness, most contractors will recommend and use hot-applied crack sealants. There are two different types—direct fire sealants, in which heat is applied directly to the sealant in direct fire kettles, and oil-jacketed sealants, in which heat is indirectly transferred from hot oil to melt the sealant in an oil-jacketed melter. The oil-jacketed variety are better for heat control and, thus, are preferred for larger applications.
The Right Process
Preparation of cracks prior to sealant application is essential. An air compressor may be used to blow out any dirt and debris. Routing is another method that will clean out cracks while producing uniform edges on the cracks, a deeper reservoir for the liquid sealant to fill, and a better sidewall to enhance adhesion of the sealant. In fact, routing cracks prior to installation provides a 40% greater chance of sealant success! A word of caution: routing should not be done if the pavement is in older shape, or greater than 20% crack density.
The Right Results
For optimum success, crack repair should only be executed in dry conditions. A heat lance can be used to eliminate bond-destroying moisture. But, if any moisture remains in the pavement, it will decrease the effectiveness of the seal or create frost action in colder temperatures which will render the seal ineffective. And, lastly, your contractor should apply sealant in accordance with the manufacturer’s recommended temperature range, which is typically in air and pavement temperatures above 45°F.