When it comes to “Going Green” in the paving industry there are a few different things to consider. In the instance of DRS’s Patented Rubberized Asphalt it is a no brainer…we take rubber tires that would be headed for the landfill and add them back to improve the mix by increasing the adhesion and flexibility of the asphalt. When it comes to using recycled asphalt as base material it makes sense as well. This not only saves new material from being used, but will have added strength due to the small amount of glue already on the stone.
Now here is where it gets tricky…lets talk about adding that old recycled asphalt and old asphalt shingles to your new asphalt mix. One of the best properties of new asphalt is that it can be a hard surface but still maintain a small amount of flexibility. This allows it to support heavy loads without deforming, but flex and move without cracking. That flexibility is due to initial properties of the Asphaltic Cement (AC) used in the asphalt mix. The problem is that over time those qualities change, and the AC that was initially soft and flexible is now hard and brittle. Now imagine truck after truck of old asphalt being dumped in a pile, then crushed, and piled up again. It would be virtually impossible, not to mention extremely expensive, to test and verify the quality of the AC in every load that came into the plant and was about to be used in the asphalt mix. So, best case scenario, samples are taken and a baseline is established…From there the manufacturer must decide what ingredients are necessary to bring the AC back to its desired flexibility. Keep in mind that all of the options will involve them spending money.
Originally, one of the ways to correct, or at least improve on this problem, was to add asphalt shingles to the mix as well. Asphalt shingles are produced with a softer AC so when they are added to the mix it produced a more flexible product. Although this can still be a problem because those shingles could also be 30+ years old and may have lost most of their flexibility as well. Not to mention that the amount of man power and equipment necessary to properly process dirty shingles can be very expensive in itself.
The bottom line is that if recycled materials are used there are a lot of factors that have to be taken into account and corrected. If done correctly their is a small margin of profit to be gained while still producing a quality asphalt mix. If done incorrectly there is a very large margin of profit but it comes at the expense of your asphalt, and defeats the purpose of “Going Green” in the first place. After all, what good it reusing a product if it means you will have to redo it twice as often?