Globally, over 680 million tonnes (750 million tons) of reclaimed asphalt pavement - RAP - are generated annually. However, on average, only a small fraction of RAP, less than 20%, is being recycled or reused with the rest going to landfill.
To help boost the use of RAP, Sripath developed a product to rejuvenate the aged bitumen in RAP and effectively restore and rebalance the functionality of the binder. The rejuvenator, ReLIXER, was commercialised by Sripath in 2015 but recent results have confirmed its effectiveness, according to the manufacturer, based in the US state of New Jersey.
ReLIXER is a specially formulated from environmentally friendly bio-based oils. Sripath says that it generates no volatile organic compounds, lowers greenhouse gas emissions, lowers the carbon footprint and is not a burden on the food supply chain. ReLIXER is user-friendly, highly efficient at low dosing levels, easy to incorporate into a mix plant, non-hazardous to ship and use and safe to handle.
Sripath says that since its introduction, ReLIXER has been vetted, tested, approved and listed by leading experts in academia, transportation agencies and industries from around the world. The product has been commercially used to pave road using high RAP mixes since 2016 in North America and Asia. Trials are underway in South America, Australia and Europe.
In every instance, the results speak resoundingly of the effectiveness and benefits of ReLIXER. For example, in the US, ReLIXER is the only approved rejuvenator for commercial use by the Illinois state’s toll highway authority, Illinois Tollway.
The 475km network consists of six tolled highways ranging from six to 12 lanes, all of which are subject to high traffic volumes and extreme weather conditions, both summer and winter. As part of the state’s approval process, Sripath Technologies collaborated in a project with the University of Wisconsin, S.T.A.T.E. Testing, Plote Construction and Illinois Tollway.
Close to 5,000 tons (4,535 tonnes) of a 40% RAP mix was produced to lay down eight lane-kilometers of top and base courses on US Interstate Highways I-88 and I-294, as well as some private roads in the area. ReLIXER additions at 2% and 3.6% of total bitumen content were evaluated.
ReLIXER was very effective in penetrating the RAP particles and rejuvenating the aged bitumen. The contractor was able to reduce overall mix cost by reducing the amount of virgin bitumen needed for the job. At the same time, the high-RAP mix with ReLIXER met all specifications and targets established by Illinois Tollway.
In another situation, ReLIXER was used on a high-profile project in New York City. A stretch of road, subject to high traffic volumes as well as much stop-and-go traffic and harsh weather conditions was paved four years ago. ReLIXER was used to rejuvenate the bitumen in a mix consisting of 100% RAP, with no virgin binder or aggregates. ReLIXER was dosed directly onto RAP particles at a dosage level of 0.55 wt% of mix. The paved road met all the specifications established by the local transport authorities.
ReLIXER has been specially formulated to deliver outstanding aging performance when compared to alternative rejuvenators. Properly rejuvenated mixes dosed with ReLIXER can give equivalent performance to low-RAP or no-RAP mixes, even after extended aging.
ReLIXER is easy to incorporate into existing plant operations. The low-viscosity, free-flowing blend of bio-based oils can easily be pumped from tote or bulk tank into the bitumen tank, injected into the bitumen feed line to a drum or batch plant or directly onto RAP particles on a conveyor. The product is safe to handle and is stable at mix, use and storage temperatures.
ReLIXER can also be used to produce hot patch and cold patch mixes for the repair of potholes during off-season. ReLIXER Hot & Cold Patch Mixes incorporate high levels of RAP and are easy to manufacture, lay down and compact.
ReLIXER can also be added in small doses to create ReLIXER Rejuvenating Emulsions for repair and maintenance applications, such as slurry seal, chip seal, scrub seal and fog seal. A rejuvenating emulsion helps soften and rejuvenate the aged pavement surface and improve bonding of aggregate to a road surface. This improves durability and performance of the repaired roadway. Furthermore, it allows use of fractioned RAP particles instead of fresh aggregate for such applications.