“Performance for a Lifetime”
By Clifford Ursich, P.E., President & Executive Director of Flexible Pavements of Ohio
While it seems the world’s business model is best described as “the race to the bottom”, it’s encouraging knowing the asphalt industry is taking a different tack. “Performance for a Lifetime” is the new driving initiative of the Nation’s asphalt industry to exceed owners’ expectations of asphalt’s attributes and provide overall higher value than any other pavement type and preservation strategy.
Defining “Performance”
Roadway engineers are familiar with the word “serviceability”, a metric used – in large part – to quantify performance of a pavement as measured through a motorist’s Seat-O-Meter. “Performance for a lifetime”, however, suggests considering metrics that includes more than what is felt by the seat of the pants. Longevity, maintainability, sustainability, and smoothness encompass the overall value of an asphalt pavement.
Longevity
Probably the greatest asphalt industry discovery has been the concepts that underpin perpetual pavement. Perpetual pavements are asphalt pavements engineered to provide inexhaustible structural life, having the need only for routine wearing (surface) course restoration. “Inexhaustible structural life” infers the pavement will sustain current loading conditions in perpetuity. Many of Ohio’s heavy duty pavements perform as perpetual pavements though not initially designed as such. Years upon years of asphalt pavement build-up has brought many into perpetual pavement status.
The value received from this pavement design method is multi-faceted. Financially, once the initial investment is made in constructing a perpetual pavement it will not require future major rehabilitation, therein reducing future costs. Considering sustainability attributes, future need for virgin materials is reduced. Energy needed to extract, transport, manufacture, and place is also reduced. , Perpetual pavements support maintainability by reducing scope of work needed to keep the pavement in good condition. Lastly, the cost of constructing a perpetual pavement is never less than when the pavement is first constructed.
Figure 1: Perpetual pavement facilitates maintainability.
Maintainability
I find the agency people who most appreciate asphalt’s attributes are those who maintain the roads. When questioned why they use asphalt, invariably the response is “ease of maintenance”. And it’s true! When asphalt goes bad, it’s skin deep – and occasionally into the dermis. Even with the potholes we are currently experiencing from our winter mix of weather, the pavement will soon be restored to new condition without extensive intervention. While we sleep roads are renewed in time for our morning commutes.
A lot of innovation is going on in Ohio to extend the maintenance cycle. Efforts are being made to make asphalt pavements increasingly durable and long-lasting. Highly Modified Asphalt (HiMA) has for the first time been incorporated into a minor rehabilitation project to improve elastomeric properties and toughness.
Research is being conducted under the auspices of ORIL to evaluate the effects of rejuvenators in ensuring asphalt mixes with high reclaimed asphalt content have as good durability characteristics as mixtures composed solely from virgin raw materials. Columbus is home to a one of a kind (in the USA) asphalt manufacturing process that can expand the effective use of reclaimed asphalt pavement. ODOT is evaluating performance prediction tests that identify asphalt mix formulations that are less likely to prematurely crack under Ohio environmental conditions and traffic loads. The 2019 ODOT Construction &Materials Specification book includes a new specification (Item 447) to deal with the nagging problem of deterioration where lanes of pavement are joined together. Nationally, equipment manufacturers are rolling out better tools – “intelligent” construction equipment and automation. All of this bodes well for longer pavement life.
The Clincher
There’s a lot of things great about asphalt pavement. For me the clincher is that asphalt is so simple. Its use facilitates predictable pavement management. With asphalt pavement you’re not going to experience the surprise catastrophic, budget busting cash outlays for pavements that require slab replacement, or complete removal and replacement. With asphalt you’re not going to shut down storefront businesses. Rather, with asphalt you have a systematic approach to pavement maintenance in which pavement resurfacing can be planned, budgeted, scheduled, and constructed with minor intrusion to people’s lives. With a solid asphalt layer undergirding, asphalt pavements merely require refreshing with a new surfacing material the likes of a thinlay.
Sounds like the kind of performance the public might like for a lifetime.
You may learn more about the asphalt industry in Ohio by visiting www.FlexiblePavements.org.
