Pavement maintenance and repairs become progressively and exponentially more expensive to remedy the worse they get, which underscores the importance of having a good preventative maintenance strategy.
Industry experts and engineers utilize a so-called “Pavement Condition Index” or PCI to assess the overall condition of a pavement structure. The scale runs from 0-100, with brand-new properly-installed pavements registering a 100 on the scale and working their way down from there. While the scale utilizes a qualitative method for assigning a value, it nonetheless provides a nice benchmark in determining a maintenance strategy and cycle.
The Asphalt Institute defines pavement maintenance and repair as “routine work performed to keep a pavement, under normal conditions of traffic and forces of nature, as nearly as possible in its as-constructed condition.” That is to say, keep it as close to 100 on the PCI as possible… It is recommended to keep that score registering around the 70 threshold or above because repairs begin to become reactive rather than preventative and consequently more expensive when below 70.
In the PCI cycle, the Asphalt Institute classifies three types of pavement repairs: maintenance, rehabilitation, and reconstruction. Rehabilitation can typically cost 10 times as much as maintenance and reconstruction can cost much more than that.
An effective preventative maintenance program involves (in increasing order of importance) crack filling, drainage management, patching, and seal coating. See our article titled “Examining the top three enemies of pavement: Water, water, and water” for more useful information on this topic. Most pavement problems start with small cracks which ultimately lead to widespread cracking after moisture intrusion. The Asphalt Institute estimates that once approximately 20 percent of a pavement structure shows “alligatoring” cracking at the surface, preventative maintenance and patching becomes useless because there is more widespread damage underneath that isn’t visible at the surface, and rehabilitation is then required. All “alligator” cracking starts underneath the pavement in the sub-base or sub-grade and works its way upward to the surface. So pavements can have all sorts of invisible, yet imminent, problems.
In its 7th Edition of The Asphalt Handbook, The Asphalt Institute provides this illustrative analogy which serves as a good summary of the importance of preventative maintenance: “A good analogy for preventative maintenance is the painting of a house. When the paint fades, it is repainted; the responsible homeowner does not wait until the paint is cracked and peeling. As with painting a house, the effectiveness of the preventative maintenance is directly related to the condition of the pavement.”
The biggest contributor to asphalt damage and deterioration is – fortunately and unfortunately – the easiest and cheapest to prevent. The reason it’s unfortunate is because most property owners and managers have a reactionary mindset with regard to pavement maintenance, rather than a preventative one. This is a truly classic example where an ounce of prevention is worth a pound of cure. If you’re going to have anything done to your parking lot, having a qualified contractor perform crack filling is by far the highest priority.
According to the Asphalt Institute’s Mike Sonnenberg, the three largest contributors to asphalt damage are “water, water, and water.” Moisture penetration through the surface to the pavement sub-base and sub-grade can cause an array of new and more costly problems to the surface pavement including potholes and widespread cracking or “alligator” cracking. Furthermore, the sub-base can become damaged. The remedy for each of these failures becomes progressively and exponentially more expensive: (1) crack filling is cheap (2) pavement patching is more expensive (3) sub-base rehabilitation is more expensive still.
An appropriate course of action is as follows:
- Quickly identify new surface cracks and address them at the latest within one or two seasons after cracks appear. So if cracks appear in the spring, they should be filled in the fall.
- The most appropriate time to fill cracks is in cool weather – either in the spring or the fall – because the crack width is at its median point. Asphalt material expands in hot weather and contracts in cold weather, so in the spring and fall, cracks will not be at their widest or narrowest. If cracks are filled in the summer when cracks are at their narrowest, the amount of material in the crack may not be sufficient to keep the crack sealed when the pavement contracts in the winter. Likewise, if we fill cracks in the winter, we may have too much material such that in the summer, the material will bulge out and be increasingly likely to be torn out by crossing vehicle traffic. In the Puget Sound, this is not as critical because we don’t experience the wide temperature swings between seasons like other places such as the Midwest. Consequently, the variance in crack openings is not as large.
- Candidates for crack filling are those between 1/8th of an inch and 1.5 inches. Cracks narrower than 1/8th of an inch are too narrow to have the material appropriately penetrate the crack and adhere to the inner sidewall. Cracks wider than 1.5″ should be filled with a Class G hot mix asphalt or a polymer.
- Cracks should be cleaned and dry before they are filled with the crack filling material.
- A hot-apply crack filler is the most effective product. We use a product call DuraFil.
- The crack should be filled to flush with the pavement surface or slightly recessed, up to ¼ of an inch below grade and smoothened with a squeegee or torch. If too much material is applied and it bulges at the top, it has a higher likelihood of being torn out by crossing vehicle traffic, particularly during hot days.
- Crack filling is appropriate for solitary cracks but not for widespread cracking or what is known as “alligator” cracking. Those areas require removal and replacement patching.
Under most circumstances, crack filling is going to cost between $1 and $2 per lineal foot for cleaning and filling. This modest cost can potentially prevent thousands of dollars of rehabilitation or reconstruction of the pavement layer and the sub-base and sub-grade layers from asphalt damage. We strongly recommend it.
With motivations of continually building a better organization, owner Tom Merry travelled to Charlotte, NC Feb. 18-20 for the National Pavement Expo.
Merry earned 6 Professional Development Hours (PDEs) from the Asphalt Institute (www.asphaltinstitute.org) while attending courses covering: (1) Overview of asphalt materials; Liquid asphalt, emulsions, aggregates, and mixtures; (2) Asphalt construction – The right mix on the job and placing it correctly; (3) Asphalt construction – Proper compaction and working with quality control specs; (4) Maintenance techniques – Patching, crack sealing, and surface treatments.
Merry also attended classes for “Understanding Pavement Defects” and “Proper Sealcoating Estimating.”
Last month, Rainier Asphalt & Concrete established and filled the position of Internal Auditor for Safety and Quality Control. New insights gained from this month’s conference will be implemented into the company’s policies and standards.
“We are continually searching for ways to distance ourselves from our competition and showcase to our customers that we are an informed and accountable contractor,” Merry said. “The important thing now is to go back home and implement this information into the way we do business — with our estimators, project managers, foremen, and quality control auditor.”
With the creation of the internal auditor position, the company seeks to provide a mechanism of accountability that very few contractors can showcase to their customers.
“We deal with outside inspectors very regularly on government jobs and right-of-way projects, but we wanted to create a quality control system on all of our private jobs, too,” Merry said. “I really believe we’re placing ourselves into the small minority of upper echelon contractors.”