Crumb Rubber as a Sustainable Aggregate in Chip Seal Pavement

The U.S. companies need to mine billions of tons of raw natural aggregates each year. In the same time, billions of scrap tires are going to landfills every year which makes the replacement of using natural aggregate with recycled and sustainable one is more beneficial to both industry and environment. This paper presents an extensive study on the performance of the chip seal pavement surfaces in terms of aggregate retention and performance. This study introduces a new eco-friendly chip seal by implementing the crumb rubber made of recycled tires as aggregates for such surface dressing. Twenty four specimens of chip seal were prepared and tested under three tests investigating the aggregate retention. The tests included the standard Vialit test, modified Vialit test, and sand patch test. Two types of emulsions, two types of binders, and three types of aggregates including the crumb rubber were examined in the tested specimens. This study revealed that the crumb rubbers from recycled tires would be used in the chip seal as aggregates but it is preferable to be used in conjunction with the conventional aggregates. The crumb rubber showed a remarkable performance in aggregate retention. This performance was mainly because of the low weight of the crumb rubber and its rough surface, which increased holding the crumb rubber into the asphalt emulsion or binder. In addition, crumb rubber as a partial or total replacement for the mineral aggregate was successfully implemented in the field using the traditional procedure and equipment.