Asphalt Pavement Crack Sealing
American Pavement Preservation
By Eric M. Reimschiissel
Placing the right treatment, on the right road, at the right time, at the right price.
Every winter I receive calls and questions from property managers and property owners about the cracks appearing and widening in their asphalt pavement surfaces. They see new cracks developing and the existing cracks becoming wider and more noticeable. They are questioning what to do if anything. I have always commended the managers and owners who are aware the conditions of their asphalt surfaces and want to do continue to keep the asphalt surface in good condition. Surface cracking is one of the first signs of a pavement beginning to age and show stress from the weather and traffic. Cracking in the asphalt surface could be an indication and a cause of early asphalt pavement surface and asphalt pavement base failures.
Asphalt pavements are designed to be a flexible surface, to move and flex as traffic drives over the surface and to be pliable enough to withstand the contraction and expansion caused by the winter and summer weather temperature changes. These temperature conditions are more extreme in our Las Vegas climate, hotter summers and cool winter conditions create more stress on our asphalt surfaces. During the summers heat the pavement expands and conversely during the colder winter weather the pavement contracts. Asphalt pavements are designed to adjust to these temperatures changes, but as an asphalt pavement ages the asphalt become more hard and brittle with less ability to absorb the changes in the temperature from summer to winter. During the winter months as the temperatures cool the pavement contracts and cracks begin to appear in the surface. As the heat of the summer months arrives the pavement expands and cracks become smaller. These temperature conditions are more extreme in our Las Vegas climate, hotter summers and cool winter conditions create more stress on our asphalt surfaces. As the asphalt pavement ages these cracks become larger each year with the asphalt absorbing the movement less and less each year. These open cracks allow water to pass through the asphalt surface into the base material underneath. Once the base material becomes wet the base material can fail to support the asphalt surface and the loads the surface is intended to carry such as truck and vehicle traffic.
In order to prevent water and elements from entering the crack causing base failures the cracks need to be sealed. We have all seen the dark random lines on some of the asphalt surfaces we drive on where cracks have previously been sealed. These lines are not necessarily eye appealing but indicate the asphalt owner is taking care of their asphalt surface by crack sealing.
Crack sealing is typically accomplished by placing a hot rubberized crack seal material in the open crack. The hot rubberized material is usually a design of asphalt blended with used tire rubber or special polymers to make the crack seal material flexible. The crack sealant is designed to be placed in the crack and be flexible enough to move and stretch, like an elastic band, as the crack narrows and widens with temperature changes. Typically cracks wider than 1/8 to 1/4 inch are sealed. Smaller cracks are too small to be filled with sealant. The joint between the asphalt and the concrete curb line should be filled also. The rubberized crack sealant will prevent water and the elements from entering the pavement surface through the cracks and joints. The best time to seal the cracks and joints is during the cooler months of the year because the cracks are wider from the cold weather contraction of the asphalt pavement allowing more crack sealant to be placed in the crack.
Picture of American Pavement Preservation crack sealing surface cracks and curb line.
Please note that once the pavement has a crack the crack does not go away. Once crack seal is placed, the crack is sealed from moisture intrusion but there is still a crack in the asphalt. Treating the cracks with a rubberized crack sealant is important but more important is the process of taking care of the asphalt pavement surface when it is new to prevent premature cracking. Seal coating asphalt pavements when the asphalt is new, within two years of placement and continued sealcoat application protects the asphalt from the sun and elements and prevents the asphalt from becoming hard and brittle, thus preventing cracking. Seal coating prevents and delays asphalt surface cracking.
Eric M. Reimschiissel
President American Pavement Preservation