FEATURE
SHRP H106, 1991 – 1999
So what’ s the best crack-sealing method to ensure long-term performance and maximum pavement life? During the 1990s, the Federal Highway Administration conducted a multi-site experiment across the U. S. and Canada, testing different crack-filling and sealing methods in a combination of hot, cold, dry, and wet climates. The study showed that routing, cleaning, and then sealing cracks provides the best sealant longevity. When cracks were treated with a simple“ band-aid” of sealant over the top, the sealant lasted 44.5 months on average. By comparison, when cracks were routed and then flush-filled, the sealant lasted 70 months. Adding a band-aid over the reservoir extended sealant life to 94.5 months— nearly eight years. Why does routing make such a difference? First, it prevents adhesion loss by creating a uniform bonding surface. Meandering crack widths can lead to differing tensile strain along the length of the crack, while loose material can inhibit a strong bond. Second, routing creates a reservoir for the sealant. In hot summer months, pavement cracks narrow, squeezing the sealant above the surface where it is worn away by passing vehicles. When an unrouted crack widens again in cold weather, the remaining sealant may stretch beyond its elastic limit and fail. A routed crack, however, retains enough sealant in its reservoir to compensate for the widening gap.
Heating the sealant to the proper application temperature is also crucial. Sealant that is too cold may not have all its components activated, while overheating can degrade performance characteristics. The optimal approach is using materials and equipment designed to work together, ensuring temperature accuracy and maximizing performance. The studies highlighted here are only two examples of the numerous research efforts undertaken to establish best practices at the local, state, and federal levels, as well as among academic and industry groups. Every advancement saves money, time, labor, frustration— and sometimes even lives. When the job is done right, you can take pride in knowing it will last, and your customers or constituents will appreciate the difference.
Patrick Yeagle is a Content Marketing Specialist with Crafco, Inc. He can be reached at Patrick. Yeagle @ crafco. com
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