3. OVERVIEW AND RECOMMENDATIONS 3.1 Surface Treatments Observations Sprayed trial are used extensively under wide range conditions including heavily trafficked roads. Under these conditions Crumb Rubber binders have provided an increase in service life over other modified binders. Periodic maintenance (sealing, slurry) is scheduled as a preventative maintenance treatment rather then applied on a worst first basis Rejuvenation is a widely accepted practice that can extend the life of seal by 3 4 years – Triple trial and sand seals could prove useful in specific situations that currently are not catered for. Recommendations Provide guidance and assess risks on the use of spray seals under heavy traffic for reseals and new works Trial South African spray seal configurations and aggregate spread rates Continue the use of rejuvenation to extend the life of seals. Provide input on South African asset management practice into Austroads project AT1536 Good practice in reseal programming 3.2 Binders Observations Bitumen supply constraints will support importation with consideration being given to performance based testing and specifications Use of wet blend field blended crumb rubber bitumen in seals and asphalt Use of polymer modified bitumen emulsions to extend sealing season Recommendations Increase the use of field blended CRB for spray seals and wet blend CRB for asphalt wearing courses Use PME’s for constructing in winter based on TG1 specifications Make use of dilute emulsion for cover sprays Make greater use of rejuvenation treatments to extend the life of existing aged Improved binder handling and test methods
3. OVERVIEW AND RECOMMENDATIONS 3.1 Surface Treatments Observations Sprayed are used extensively under wide range conditions including heavily trafficked roads. Under these conditions Crumb Rubber binders have provided an increase in service life over other modified binders. Periodic maintenance (sealing, slurry) is scheduled as a preventative maintenance treatment rather then applied on a worst first basis Rejuvenation is a widely accepted practice that can extend the life of seal by 3 – 4 years Triple and sand seals could prove useful in specific situations that currently are not catered for. Recommendations Provide guidance and assess risks on the use of spray seals under heavy traffic for reseals and new works Trial South African spray seal configurations and aggregate spread rates Continue the use of rejuvenation to extend the life of seals. Provide input on South African asset management practice into Austroads project AT1536 Good practice in reseal programming 3.2 Binders Observations Bitumen supply constraints will support importation with consideration being given to performance based testing and specifications Use of wet blend field blended crumb rubber bitumen in seals and asphalt Use of polymer modified bitumen emulsions to extend sealing season Recommendations Increase the use of field blended CRB for spray seals and wet blend CRB for asphalt wearing courses Use PME’s for constructing in winter based on TG1 specifications Make use of dilute emulsion for cover sprays Make greater use of rejuvenation treatments to extend the life of existing aged Improved binder handling and test methods trial trial
2011_AAPA_Study_Tour_Report_v4-2.docx