Field trials of unbound granular pavements treated with an insoluble dry powdered polymer

Unbound granular pavement materials deteriorate with traffic, time and water ingress. In-situ recycling of fatigued pavement layers can be cost-effective, provided that appropriate additives are chosen. The polymer additive used in this study is suitable for aggregates with clay-rich fines. It is an insoluble dry powdered polymer (DPP) and is a proprietary product. According to Australian Road Research Board’s certificate, DPP is a granular powder comprising a cationic polymer thermally bonded to fine ground limestone. Long-term field trials of two in-situ recycled road sections on semi-rural roads were established to support an ongoing laboratory investigation. The polymer was suitable for these trials due to poor site drainage and risk of flooding. Field data from the La Croix deflectograph indicated good performance of the treated sections compared to the adjacent control sections. At the first site, the average central deflection under wheel loading over five years of monitoring was 0.3 mm compared with 0.6 mm over the control section. The second site initially showed similar level of improvement (0.5 mm compared with 1.1 mm), but deterioration of the treated pavement became evident with average deflections increasing to 0.8 mm by spring of 2020. Central deflection information can be supported by deflection ratio data. Visual inspections of road conditions highlighted the need for caution with shrinkage of the material treated with DPP. Transverse shrinkage cracks between 1 and 2 mm wide were observed. Laboratory testing of one of the granular materials confirmed high levels of shrinkage.


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  • Accession Number: 01887995
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 19 2023 9:38AM