Let me begin with something obvious today. One of the ways to increase the use of recycled asphalt pavement (RAP) and thus decrease the perceived horror of using virgin materials in pavement construction is to remind—or convince—state departments of transportation (DOTs) that using RAP is a positive. We, as an industry, would like to share the message with our DOTs and other agencies that increasing RAP percentages in various lifts, including substantive surface courses and thinlays, yields a long-lasting and environmentally responsible product for taxpayers.
Agencies typically wish to reuse and recycle these days. But state DOTs are notoriously cautious when it comes to throwing “used materials” into their mix designs. And they should be. Asphalt pavements are not and should not be landfills.
Let me reiterate for absolute clarity. It is the opinion of the editor of AsphaltPro magazine that asphalt pavement systems are not and should not be modern day landfills.
While asphalt mix designs of course have room to incorporate novel materials, with additives to enhance adhesion, blending, viscosity or what have you, the industry works to maintain high quality of performance. A smooth, long-lasting roadway is truly environmentally responsible in that its smoothness leads to improved gas mileage (and less wear) for the vehicles traveling upon it and its longevity leads to fewer materials (and funds) required to preserve and maintain it.
By paying attention to the inputs’ potential for performance, we get a better outcome. Isn’t there an adage about garbage in, garbage out? Then let us turn to the materials going into the mix design and consider carefully not only their carbon footprint(s) but also their potential to perform or fail two, three or four years down the road. You can bet the engineers at the DOT are considering it.
If we, as an industry, continue to show good faith in building quality pavements with excellent materials as inputs in our environmental product declarations (EPDs) and use of best production and paving practices, we win the confidence of the DOTs who may have seen less than stellar results in experimental products of the past. It’s no secret that some DOTs still look askance at high-RAP in surface courses. There are entities who have had negative experiences with crumb rubber, various additives for rejuvenation and so on. These unfortunate moments don’t have to hinder the use of high percentages of RAP.
As an industry, we know how to increase RAP content in mix design and pave a long-lasting roadway for taxpayers. We can prove to agencies that we have the integrity to use quality materials that are both environmentally friendly and high performing in a low-bid system. For this month’s “Paving For Bonus” issue, I encourage thinking along the lines of how to incorporate higher RAP mixes in upcoming paving projects, but doing so with highest quality for longest lasting pavements in mind. All eyes are on the carbon footprint these days, but I can guarantee all eyes will be on performance two, three or four years from now. Let’s make sure we’re still giving agencies the best pavement choice with best material inputs.
Stay Safe,
Sandy Lender