What is RAP?
Reclaimed Asphalt Pavement (RAP) Material Explained
When it comes to sustainable road construction, reclaimed asphalt pavement, or RAP, is something of a game changer, representing a significant move toward a circular economy and transforming how we approach infrastructure projects. With environmental concerns giving increasing importance, taking RAP is paving the way (quite literally) toward a more sustainable, circular future for our roads.
RAP, simply put, is a recycled product derived from previously used asphalt materials. As roads reach the end of their life, they’re resurfaced, and the materials removed in that process are recycled and repurposed. This circular approach to asphalt is changing the construction industry and demonstrating that today’s pavements can indeed be tomorrow’s. Innovative solutions, like our own Foamix, are also leveraging RAP material to reduce our environmental impact and carbon footprint, expanding the range of applications for RAP.
Composition and Production of RAP Material
So, what is RAP asphalt made of? The composition of RAP includes high-quality aggregates and an aged asphalt binder. When roads are resurfaced, RAP material is created by milling or removing layers of old pavement. This reclaimed material is then crushed and screened, making it fit for purpose in new pavement projects.
The process may sound simple, but it’s highly technical. During the crushing and screening stages, the RAP is refined to ensure consistent quality and usability. This transforms what would have been waste into a valuable material that saves on new resources and offers a second life to existing ones. To find out more about innovations around RAP, check out our Crawley RAP train project, a leading example of reclaiming asphalt for sustainable road building.
Clearly defined section of road that's had asphalt scrapped from it's surface
Properties of RAP Material
RAP is a versatile material, but not all RAP is created equal. Its properties vary based on the original pavement and the milling or reclaiming processes used. For example, gradation (or particle size distribution) plays a crucial role in RAP’s effectiveness. The aged asphalt binder properties (such as penetration and viscosity) can differ widely, depending on the condition of the original pavement.
This variability means that RAP quality isn’t one-size-fits-all. Each batch has a unique profile, and understanding these characteristics is key to producing reliable, durable new pavement. In many ways, RAP material is as customisable as it is sustainable. This extends to cold-mix asphalt applications, allowing for flexibility in various weather conditions and infrastructure needs.
Applications of RAP in Road Construction
Once ready, RAP is mixed into new asphalt, providing a recycled option for both hot and cold-mix asphalt, where it can make up anywhere from 10% to 50% of the total mix.
Cold-mix asphalt products, like our Foamix, utilise RAP for better workability at lower temperatures, providing energy and carbon savings and a durable option for base and binder courses.
Foamix has already been used as part of a comprehensive suite of materials on the UK’s first carbon-neutral highway construction scheme between the M6, 36 junction and Brettargh Holt roundabout. The works formed part of the estimated £8m award winning A590 Brettargh Holt scheme, which was designed with a low carbon strategy in mind to deliver safer and smoother journeys for road users. This saw us collaborate closely with National Highways and others to engineer a pavement design and material specification that would unlock significant carbon reductions and cost benefits.
This machine is screening and sorting the recycled asphalt plannings by size
Benefits of Using RAP Material
Here’s why RAP material is becoming a staple in sustainable construction.
Environmental Advantages
Using RAP means fewer natural resources need to be mined. And less mining means a smaller environmental impact, less disruption to ecosystems and a tangible reduction in greenhouse gas emissions. It also keeps tons of asphalt out of landfills, contributing to cleaner, more sustainable communities.
Performance and Durability
If you’re thinking ‘doesn’t recycled asphalt mean it’s second-rate?’, think again. Thanks to innovative technology and stringent quality checks, RAP can perform as well as or even better than virgin asphalt. Aggregate Industries’ RAP products are formulated to withstand heavy traffic, changing weather, and the daily wear-and-tear that comes with any busy road.
Quality Assurance testing
While RAP has numerous benefits, there are challenges too. Because RAP’s properties can be inconsistent, influenced by factors like the original pavement’s condition and the milling process, projects using higher RAP percentages often require adjustments in mix design, like adding softer virgin binders or rejuvenating agents to balance the aged material.
wRAPping things up
In the ongoing search for more sustainable and circular construction methods, RAP material plays a significant role. From reducing reliance on new resources to repurposing what’s already available, RAP is evidence of the circular economy in action. While there are limitations to consider, RAP remains a viable way of creating roads that are as kind to the environment as they are tough on traffic, without sacrificing performance. To find out more about our range of RAP asphalt, just contact our experts to find the right solution for you.
