#1 Selecting the Right Pavement Preservation Products

The primary problem with pavement preservation is treating the pavement surface at the right time with the right product.   Sounds easy?  Well it isn’t!  One of the challenges is that due to reduced funding, agencies are forced to adopt a reactive approach to managing their road networks.  All municipalities want to protect their roads but budget cuts mean that the allure of the cheaper preservation materials are being put to the test on rehabilitation projects where the pavement has gone way past the 40% structural life – which is the sweet spot proposed by the pavement preservation association and the FHWA.

However, is something better than nothing?  It all depends on the product, but a few more important questions should be asked– why should I consider a pavement preservation product in the first place and what elements should I keep in mind when making a selection?   What should I watch out for when looking at products of multiple price points? Once purchased and implement, how can I maximize the performance of our pavement preservation treatment?

While the answer to all these questions would require an extensive conversation, below are some of the key elements to note when making this important decision.

Pavement Preservation – Remember, communities rely on easy and safe mobility on well-maintained roads.  Whether considering a highway or county road project, these infrastructures are costly to build, maintain, and rehabilitate.   Increasing the capacity of these tax-payer funded infrastructures is a fiscally responsible step that increases the value and life of roads as well as helps meet the important needs of the community.  Pavement preservation products can be the line item that saves money in the long run –talk to your contractor about them.

Surface Distress – It is not always the road traffic that prevents a pavement preservation product from performing at its highest level, but rather the degree and extent of surface distresses (such as reflective cracking) before the product is applied that impacts effectiveness.  When selecting a pavement preservation product, make sure its materials are specialized in addressing your existing surface distress.  By focusing on this element it will automatically help you narrow down the products relevant to your overall needs, help you create a short list of products that will extend the life of your roads by healing them with the right treatment, and help you compare apples-to-apples when conducting a price analysis.

Functional Distress – Surface distress (such as reflective cracking) is commonly found on all projects that are demarcated as ideal for maintenance and rehabilitation. However the functional distress of a road also needs to be considered.  Parking lots are great examples of this where untreated construction joints trigger water damage and then expedited structural deterioration.  So can the treatment address reflective cracking with interlayers?  Chip seals are now being used with paving fabrics!

Quality of Materials Used – Clearly there are countless low cost alternatives, however, these options are losing their glean in the current economy.  Municipalities are realizing that many low cost pavement preservation products result in greater costs to taxpayers – the roads have to be replaced and maintained more often than comparable roads that used a better product. Therefore, I say, let’s take advantage of the speed of installation and implementation of pavement preservation systems, but increase the quality of the materials that are being used.  This will not only extend the life of the roads built, but also help communities financially weather this unpredictable climate and environmental elements by reducing overall repair needs year-to-year.

New Road Resurfacing Innovations – I mentioned before that the chip seal surface treatment recently joined forces with a pavement fabric to tackle and mitigate the effects of the underlying cracks on the new surface treatment.   There are also new systems that can be installed together with stress absorbing and paving mat interlayers to achieve a durable surface treatment.  Other innovations have been developed as well but, when evaluating them, make sure they successfully treat the road without impacting performance and use controls to allow for a proper evaluation.  The right product should bring you both improved road network performance and reduced fiscal strain on your budget.

Clearly there are countless elements to consider when selecting a pavement preservation product, but the important thing it is that any road resurfacing and road repair project include it as part of its design.  Pavement preservation products can extend the life of roads, lower long-term road resurfacing and repair costs, and enables a community to continue operating and growing.  That should be the overall goal.  I look forward to hearing other people’s opinions. 

While we watch meteorologists try to predict the day’s weather, many of us don’t stop to think about the wear-and-tear the cold, heat, rain or wind is having on the road surfaces we utilize each day.

This past winter’s extraordinary snow fall in the northeast (particularly in the Washington D.C. tri-state area) created a pothole epidemic for the states of Maryland, Virginia and the District of Columbia.  Virginia even asked its residence to help identify potholes in the state so that they could initiate a pothole-filling blitz program that lead to the successful patching of 150,000 potholes.  Many other states have had to allocate emergency funds to repair cracks and road surfaces in order to ensure the safety of its citizens. The overwhelming rainfall in the southeast and California compromised the infrastructure of roads alongside mountains and roaring rivers, and contributed to driving hazards that affected millions of people on a daily basis.

While the force of nature is undeniable, the reality is that many of these issues could have been prevented or lessened with the use of innovative pavement preservation systems.  Many of these systems, applied on new and old surfaces:

• Extend the life of both concrete and asphalt pavements.  The resurfacing and sealing properties of many of these pavement preservation systems offer an added coat of protection for the pavement that, in the long run, lasts longer and costs less to maintain.

• Brighten the surface. A brighter surface is not only more aesthetic, it also reflects solar energy reducing pavement surface temperatures and therefore also brings down surrounding air temperatures

• Can be installed quickly. Many new pavement preservation systems can be installed quickly and can be added to deteriorating surfaces —new or old.

• Are environmentally friendly. Given the focus and incentives associated with the use of environmentally friendly/sustainable products, many pavement preservation systems can help cities and counties embark on smart urban planning that includes more earth conscious choices in their construction products.

Road and pavement surface repair needs, resulting from weather, can be seen as an opportunity to explore innovative pavement preservation products that are in the marketplace.  Whether you are working through a contractor or you are part of an engineering/ urban development team, be sure to ask about pavement preservation systems that will bring your company (or your client) money-saving advantages.

Well the answer lies in the level of protection that each material offers and at what stage in the structural and maintenance life the pavement surface treatments are applied versus the cost for each material.

To effectively compare these two materials and their ability to protect the road, the following performance properties need to be understood:

• Rut resistance
• Wear resistance
• Resistance to Aging
• Fracture Resistance

Rut Resistance. Traditional ultra thin pavement preservation materials are unlikely to rut.  However, in warm climates, the supporting asphalt layers could still be prone to rut.  This means that surface treatments are required to withstand the development of rutting beneath it.  This rutting should be accommodated by both materials if the rutting is as much as 1/8” of an inch up to ¼” of an inch.  It should also be considered that both concrete and chip seal materials could reduce the rutting potential of the supporting layers by reducing the surface temperature due to their higher Solar Reflectivity Values.

Wear resistance of surface treatments is associated with friction loss due to abrasion caused by traffic wear.  The concrete materials are far more likely to offer more resistance than bituminous materials throughout its lifecycle as the product does not experience a change in state when subjected to aging, UV or extreme temperatures.

Resistance to Aging. The aging of materials is likely to cause shrinkage cracking in asphalt materials, whereas in a polymer modified concrete, minimal shrinkage is anticipated without cracking due to the hydration process in the initial life of the material.  In low humidity and high temperature environments, the concrete will show no signs of aging, whereas the bituminous treatments will age rapidly unless other measures are used to retard the aging.

Fracture Resistance. The presence of cracks in the underlying layers is likely to reflect through the new surface treatment whether they are concrete or asphalt.  However, in warmer climates the bituminous materials are more likely to mitigate the crack reflection until it age hardens.  In cold climates, the asphalt will become brittle and the cracks will reflect through due to traffic or environmental induced stresses.  Reflective cracks will reflect through the concrete materials unless additional crack reflection resistance measures are taken.  The advantage of the concrete materials is that they can easily accommodate high tensile low strain Geogrids or Geomats as the concrete and these Geomaterials are strain compatible.

So it would appear that both materials offer performance advantages in different climatic environments.   However, the concrete materials do have the advantage that they are resistant to aging, and have a high wear resistance which means that they have the ability to extend the maintenance design period significantly (10 – 20 years) in comparison to bituminous materials (2 – 8 years) thereby requiring fewer maintenance interventions.  Therefore the life cycle cost benefit should be performed using the initial cost and anticipated maintenance life for each possible intervention.

The author suggests that one considers all of the above when selecting either a Concrete or Bituminous material for your surface treatment.