Moving from a linear to a circular carbon economy

Embracing the concept of a Circular Carbon Economy and the goals set forth in Saudi Arabia’s Vision 2030, Saudi Aramco puts into action an innovation that transforms the waste produced by used tires to help build up the Kingdom’s highways.

Each year, approximately 20 million waste tires are generated Kingdomwide, bringing with them potential environmental and safety concerns. Meanwhile, only about 5% of these tires are currently being reused in some form.

A new concept introduced by the Company is looking to transform these waste tires into a resource. The innovative concept is to turn crumb rubber from the tires into a form of asphalt -- asphalt rubber (AR) -- for use in laying and maintaining roads. The innovation is one of several projects under the Corporate Green Energy Program led by Environmental Protection (EP).

Using recycled tires in asphalt pavement has significant environmental benefits, in addition to improved safety and reduced maintenance costs. AR minimizes scrap tires, thereby reducing tire stockpiles that are breeding grounds for a variety of pests, such as mosquitoes and other insects. Tire stockpiles, are a prime component of illegal dumping and a source of air pollution when burned.

Adopting the principles of a Circular Carbon Economy – where carbon or its emissions are reduced, reused, recycled, and removed (4R), EP recently teamed up with Consulting Services Department (CSD), Western Region Distribution Department (WRDD), Distribution and Terminal Projects Department (D&TPD), and the Transportation and Equipment Services Department (T&ESD) to complete a pilot.

A piloted section 160 meters long, 5 meters wide, and 7 centimeters thick was used which included AR pavement with a rubber content that was increased from the standard 10% of total asphalt weight to 20%. 

The AR mixture was produced using an innovative “modified dry mix method.” This method allowed the team to eliminate the process of pre-blending and conveying the asphalt and rubber, as the crumb rubber was added directly into the hot mix asphalt plant. The piloted section will be monitored throughout the summer to ensure performance and durability under extreme weather conditions. Once approved, the new method will be included in Company standards with subsequent outreach to the national stakeholders for Kingdomwide implementation.

Since the 1960s, asphalt mixture produced with recycled tire rubber modified bitumens have been used in different parts of the world as solutions for different quality problems. Despite some, downsides, in the majority of the cases they have demonstrated road pavement enhanced performance.

Technology unlocks a remarkable recycled product

AR is a special type of asphaltic paving material in which more than 15% of the binder content is crumb rubber from recycled waste tires. From a pavement engineering point of view, AR offers mechanical properties that are superior to conventional asphalts. As an example, AR has better resistance to permanent deformation, yes, we are referring to those annoying depressions or grooves worn into the road by heavy haul trucks. AR has greater resistance to oxidation, meaning less cracking of roads. AR pavements also help to reduce roadway noise produced by traveling vehicles, they have a darker tone of black, and a shinier appearance. 

Producing AR has its own challenges since the high content of crumb rubber makes the binder much more viscous than conventional bitumen. This makes it difficult to handle with the equipment available in the Kingdom. To overcome this, Aramco engineers researched and successfully developed an innovative method to produce the mix without major investments.

An up close and personal look at the AR pavement innovation

Mohammed Rayes from the Western Region Distribution Department, a member of the team that implemented AR pavement at the North Jiddah Bulk Plant Expansion Project shared his personal story about the remarkable innovation.

“Delivering a successful project that is being implemented for the first time in Saudi Aramco was a truly unique endeavor. I was able to work with a strong technical team to complete the deployment of AR pavement technology using a distinctive process that were deployed for the first time in Saudi Arabia.

During my assignment with CSD, I began by researching the economic and technical aspects of the challenge to discover the key values and any possible obstacles for deploying a new process, which is adds a high content of crumb rubber in the binder (about 20%).

I worked to address all challenges of implementing this technology, such as the limited local market demand for used tires and developing a new mixing process. Personally, the effort proved rewarding as I enhanced my research skills in identifying problems and developing lists of alternative solutions for technical challenges.

One of the main solutions we identified was the dry process for the asphalt mixing, which allowed us to avoid pumping issues faced with the wet process. While I was working on the feasibility study of the AR technology, I noticed vast opportunities to encourage recycling across the Kingdom.