Recycled Pavements

Using RAP in Base Layers

>Using RAP (Reclaimed or Recycled Asphalt Pavement) in road construction is attractive both economically and environmentally. Although common in asphalt repaving, the use of RAP as structural infill in road base layers is limited. RAP typically requires offsite processing and tends to creep under sustained loads.

Recycled Pavements with Neoloy Tough-Cells

Neoloy Tough-Cells 3D confinement improves the performance of recycled materials. Neoloy enables the reuse on-site RAP as a base course without processing and with a thinner asphalt overlay – due to its unique Novel Polymeric Alloy (NPA) material properties:

• Neoloy’s dynamic elastic stiffness makes additional processing (remixing binder and aggregate) unnecessary enabling in situ use 500 MPa @ 60°C validated by Dynamic Mechanical Analysis – DMA).
• Neoloy’s high resistance to permanent deformation prevents the lateral creep of RAP for design life validated by SIM accelerated test).
• Neoloy’s Modulus Improvement Factor (MIF) strengthens RAP base infill almost to the structural value of asphalt itself (validated by published lab, numerical and field testing)

Published research demonstrated that NPA Geocells are a sustainable, reliable and cost-effective solution for reinforcing RAP. They increased stiffness, reduced permanent deformation and increased pavement life by a factor of x10 (Han et al, 2012).Additional recycled materials such as recycled concrete aggregate (RCA) and masonry debris can be used with Neoloy Tough-Cells for road stabilization.

Neoloy Reinforced RAP with Low Creep

Research has demonstrated that Neoloy Tough-Cells eliminate the two barriers to more widespread use of RAP as base layer infill – the need to transport the milled asphalt for processing and the permanent deformation of the RAP material.

Unlike HDPE soft-cells, Neoloy made of NPA novel polymeric alloy exhibit very low permanent deformation under cycling loading. Extensive testing by the Mid-America Transportation Center (MATC) demonstrated that NPA Geocells (Neoloy Tough-Cells) “significantly reduced the permanent deformation of the flexible pavement and increased the pavement life by a factor of 10.”Han et al, 2012, Onsite Use of Recycled Asphalt Pavement and (NPA) Geocells to Reconstruct Pavements).

Neoloy also reduces the total amount of asphalt and RAP in a pavement to reduce the pavement thickness – 15cm thick NPA Geocell reinforced base was found to have equivalent or better performance than a 30cm thick unreinforced base.

The studies also demonstrated that Neoloy Tough-Cell (NPA Geocell) reinforcement improved the performance of the pavement, behaving like a semi-rigid mattress or slab and more widely distributing vertical stresses. In particular, the following results were recorded: 

• NPA Geocell confinement increased the stiffness of the base course and reduced its compression
• Vertical stresses increased faster in unreinforced sections, compared to NPA Geocell reinforced sections
• increasing pavement life by a factor of x10
• NPA Geocell reinforced bases sustained larger load cycles, to a traffic benefit ratio of up to 12.5
• Elastic deformation decreased in NPA Geocell reinforced sections, with just 0.80mm recorded for a 30cm section, compared to 2.93mm for an equivalent unreinforced section

Click here to see a case study with RAP

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