Construct - Issue 43

Another requirement of RAP is that the source material must come from the road, and in this case a stock of high polished stone value (PSV) RAP was required for processing into two different products. In the surface course material, the first RAP is used to replace high PSV aggregate, while in the base binder materials, the RAP is included to make it a zero-waste process. And, while the supply of recyclable material may be restricted, Vanessa explains an added upside of using it: “We take the road planings back to one of our twin drum asphalt plants, and that same vehicle then collects the new material, so we’re making carbon savings on the haulage.” FM Conway’s Technology Centre played a crucial role in the success of the M3 trial by designing the new asphalt mixes, which include the company’s own polymer “No other material supplier in the UK has this sort of facility”

M3 RAP TRIAL IN NUMBERS 36t carbon saving

120- 200mm depth of new material

modified binder (PMB). “From the planings used, they were able to evaluate the bitumen content and then match it with something

10,872m² area laid

that would give us the longevity and durability required,” explains Mark.

2,940t new surface,

“It requires an in-depth testing process, and no other material supplier in the UK has this sort of facility.” He adds that, while this trial broke records, it has more important ramifications: “It’s not just that this was a first; it’s also provided a massive learning curve – for us and for National Highways. We all need to understand how this works, given the amount of PMB material out there that’s going to need to be recycled over the next 20 years or so.”

binder and base course material

30 o C reduction in asphalt temperature

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