Crack repair:

Why crack filling is vital to asphalt maintenance.

There is no argument that all asphalt pavements crack. Cracks in asphalt are inevitable. Neglect and lack of proper maintenance of[parking areas or drive ways lead to accelerated cracking and/or potholing, further reducing the serviceability of the pavement.

Once cracks develop, water easily penetrates into the base and sub-base of the pavement and damages the structural integrity of the aggregate materials. Pavement joint and crack sealants are designed to protect pavement by minimizing water infiltration and by preventing the accumulation of debris. It has been demonstrated and documented and is generally accepted that sealing the cracks in flexible pavements is the best preventative maintenance procedure for adding many years to the life of the pavement, especially when used in conjunctions with other preventive maintenance techniques.

According to a U.S. Army Corp of Engineers, CRRL, survey of the crack sealing practices of all 50 state departments of transportation, 45 states utilize crack sealing in their standard pavement maintenance program. Event states that do not do crack sealing recognize that cracks in their pavements are a problem. States with numerous freeze-thaw cycles cited that:

• Crack sealing is an important procedure that must be addressed yearly.

• Crack sealing is one of the most cost-effective ways to prolong the pavement life, adding between 3 and 8 years when done properly.

How is the pavement deteriorated?

In pavement where the cracks have not been sealed, there are many routes to the base and sub-base courses. Water will penetrate through cracks that are over 1/8 in. wide because water will flow by gravity into the surface and then into the base course. Surface water is also pushed into cracks through the pumping action of traffic when vehicles pass over allowing water to penetrate the pavement and damage the base courses. Once water enters the base, it softens and deteriorates the base materials, causing extensive and expensive damage to the pavement.

The economics of crack sealing:

Crack sealing, like any other maintenance project, has to be done with proper economic justification, using proper materials and procedures. It is an established pavement preservation technology, which is steadily evolving to meet the challenges of modern age traffic requirements, utilizing state-of-the-art materials and tools.

Life Cycle Cost Analysis (LCCA) is defined in the Transportation Equity Act for the 21st Century (TEA-21) as “a process for evaluating total economic worth of a usable project segment by analyzing initial costs and discounted future costs, such as maintenance, user costs, reconstruction, rehabilitation, and restoring and resurfacing costs, over the life of the project segment.”

From an LCCA standpoint, crack sealing is highly cost effective and much less expensive than other preventive procedures. For example, seal coating averages 3 to 14 times more than crack sealing and an asphalt overlay costs 8 to 26 times more than crack sealing. Furthermore, it was also reported crack sealing slows the reappearance of reflective cracks in the new surface.

Pavement magazine February 2004 - Girish Dubey is president of STAR Inc., Columbus, OH. -