For years contractors in California have tried to incorporate used tire rubber into asphalt to extend the life of their roadways but with limited success. Recently, Polyco landed contracts in Northern California to assist with several paving projects powered by our proprietary Rapid Digestion Process^™ (RDP), SigmaBond a revolutionary asphalt that enables hot mix contractors to use more upcycled materials while extending the life of pavements. The results have been resounding.

Are you sure this is rubber? 

With SigmaBond, contractors had no difficulty with the placement of the mat or rake work. They noted that the product wasn’t sticky, was easy to place, contour and compact, and had density values that exceeded target values. They also reported the tensile strength exceeded regular asphalt – the only time they had seen that happen with a rubber mix. Much to their excitement, we overdelivered what was promised. 

Many state contractors still use the dry process which simply adds raw dry tires to the aggregate as a filler. The wet process mixes tire rubber into the process wet at about a 20-25% concentration. The Polyco process digests it into a liquid process allowing more rubber to be added – up to 50%.  

Jeffrey Buscheck, R&D Engineering Manager at the UC Pavement Research Center, believes that “the use of TR-modified asphalt as a tool to improve performance in California dense graded mixes is very exciting as we evolve to balanced mix design (BMD) and emphasize on improving the age and crack resistance of our pavements. We are working on evaluation studies funded by Caltrans and CalRecycle, and so far, the results of this material are very promising.”

The positive feedback kept coming as contractors noted that at any stage of the process of laying the material down, the density of compaction did not change. There was none of the stringing that traditional mixes created. They also successfully used our rubber modified asphalt in a dense graded mix which has not been done before with any other rubber mix.

California is admired for its emphasis on sustainability and offers a welcoming environment for Polyco’s products and technology as decision makers want to move away from dry mixes all together. Our SigmaBond process not only creates a superior, long-lasting road without cracking, but it saves money by cutting out the interlayers of traditional roads. Now contractors can meet the state’s sustainability goals without sacrificing performance.