Rejuvenation and Preservatives

With 75% of UK Local Highway Authorities (LAs) declaring a climate emergency and net zero targets approaching, a low-carbon approach is necessary. The challenge lies in siloed innovation, 'greenwashing,' and low carbon 'snake oil.' Often, LAs conduct low-carbon trials but don't share data, results, or methodologies widely, hampering progress and understanding. These issues led to the development of the Centre of Excellence for Decarbonising Roads (CEDR). CEDR represents one of the four themes of ADEPT Live Labs 2: Decarbonising Local Roads, a three year, UK-wide, £30 million programme funded by the Department for Transport (DfT) that aims to decarbonise the local highway network. The process of CEDR is to ingest, test and disseminate information on low-carbon materials throughout the sector. Please read more about preservatives, rejuvenators, and our recent trials.

What are Preservatives and When Should They Be Applied?

Asphalt preservation involves surface treatments that protect asphalt pavements from environmental degradation and extend their lifespan. These treatments form a thin protective layer over the pavement, slowing down asphalt binder oxidation, preventing water intrusion, and minimizing UV radiation effects. Preservatives are preventative maintenance - they do not repair significant damage but instead preserve the pavement in its current state.

Preservatives are ideal for maintaining relatively new or well-maintained asphalt surfaces.

What are Rejuvenators and When Should They Be Applied?

Asphalt rejuvenators restore the chemical composition of aged asphalt binder by penetrating the pavement surface. Over time, asphalt loses natural oils and becomes brittle due to oxidation, UV radiation, and other factors. Rejuvenators replenish these oils, improving pavement flexibility and durability. They are often spray-applied or used in pavement recycling processes, enhancing reclaimed asphalt pavement (RAP) for reuse in new construction.

Rejuvenators are most effective for pavements showing early signs of aging and surface-level damage due to oxidation but are structurally sound. By rejuvenating the asphalt surface, they help prevent further deterioration, such as cracks and potholes, keeping roads greener for longer.

According to the RSTA carbon report on treatment types, rejuvenation is currently the lowest carbon treatment, with preservation closely behind at 5th. There is potential for significant carbon and cost savings. By anticipating maintenance needs and being proactive with treatment, rejuvenators can be applied earlier in the asset lifecycle, delaying the need for surface dressing.

Reasons for Carbon Savings

Extending Asset Life

One of the biggest ways to reduce emissions is to extend the asset life. Rejuvenators significantly extend the lifespan of asphaltic pavements. Treating roads at the right time reduces the need for carbon-intensive and expensive interventions like resurfacing or reconstruction. Rejuvenation and preservatives can be applied multiple times, increasing cost and carbon benefits alongside lifespan.

Reclaimed Asphalt Pavement (RAP)
Rejuvenators enable higher incorporation rates of RAP in both maintenance and new asphalt production. For every ton of asphalt replaced with RAP, carbon emissions are reduced by approximately 20–25%, as virgin bitumen production is emission-heavy. Rejuvenators make high RAP mixtures viable, lowering CO2.
Lower Production Emissions

Asphaltic material production, especially bitumen, involves energy and carbon-intensive processes. Extending pavement life or enabling recycling significantly reduces production-related emissions. Preservatives delay the need for resurfacing or reconstruction. Some rejuvenators are compatible with warm-mix asphalt technologies, reducing the temperature required to mix and lay asphalt by 30–40°C, translating to energy savings of 15–20%.

Reduced Vehicle and Equipment Emissions

Preservatives and rejuvenators require less heavy equipment and operational hours compared to traditional maintenance and reconstruction, resulting in major carbon savings. Traditional road maintenance involves large diesel-powered machinery like milling machines, pavers, rollers, and haul trucks, consuming 50–100 litres of diesel per hour. Alternatively, preservatives and rejuvenators are applied with lighter, less energy-intensive equipment, consuming roughly 10 litres per hour.

Reduced Waste

Resurfacing or reconstruction produces large quantities of road wastage, whereas rejuvenators allow existing asphalt to be reused or restored without removal, drastically reducing waste. Rejuvenators improve aged asphalt quality, promoting a circular economy where materials are reused multiple times, reducing landfill space and virgin material extraction.

Road Closure Time

Vehicle emissions from traffic due to road closures are significant indirect emissions. Preservatives and rejuvenators can often be applied in hours compared to days or weeks for traditional reconstruction. Shorter road closures mean less idling vehicles and detoured traffic, decreasing fuel consumption and emissions.

Recent Trials

In August, the Centre’s South Campus trialed asphalt preservation/rejuvenation products across four sites in Coventry and Solihull to evaluate cost, carbon footprint, and performance. Rhinophalt, PenTack, and Reclamite were applied, covering around 30,000m2. Thorough pre-evaluations enabled rigorous product comparisons, with each product trialed against each other and an adjacent control section.

In May, the North Campus delivered two Reclamite trials, comparing its performance on different road types: Stone Mastic Asphalt (SMA) and Hot Rolled Asphalt (HRA), in collaboration with the University of Nottingham. These insights will be valuable to the Scottish local roads sector, informing future carbon-based decisions on rejuvenators.
Our mission is to empower UK Highway Authorities with vital data to make informed, sustainable decisions for the future of our roads.

What's Next for the Sector?

With increasing demand for lower carbon innovations and proactive repairs, but continually strained budgets, local authorities face tough challenges when planning works. Rejuvenation and preservation of road surfaces could be a viable alternative to traditional treatments, greatly extending the asset’s life for a fraction of the cost.

Find out more about Live Labs by keeping up to date with the ADEPT Live Labs 2: Decarbonising Local Roads, a three year, UK-wide, £30 million programme funded by the Department for Transport (DfT) that aims to decarbonise the local highway network. ADEPT Live Labs 2

Find out more about our recent trials - Rejuvenation and Preservative trials

Follow along with our decarbonisation journey: CEDR LinkedIn