Empa - Concrete & Asphalt

Highly Recycled Asphalt Pavement (HighRAP)

Objective

The objective of the HighRAP project was to develop recommendations that would allow increasing the average reclaimed asphalt content in asphalt production without compromising the pavement performance.

Duration: 04.07.2019-31.12.2022

Project Summary

The project addressed three main research topics:

1) RAP Materials

2) Mix design

3) Performance

Within these topics, individual studies addressed the characterization of RAP, improvement of RAP crushing and screening, aging and rejuvenator selection, performance-based mixture design, and construction of two test sites with high RAP content: one in a high traffic road and one at high altitude (1,900 m above sea level).

Project Activities

The HighRAP project tasks and activities for each of the three research directions are shortly summarized below.

Study	Tasks	Activities during HighRAP project
RAP milling & processing	Develop RAP processing procedures that allow maximizing the RAP use in production.	A full-scale experiment to evaluate the effect of milling. A full-scale experiment to develop a method for quantitative assessment of RAP crushing and screening procedure.
RAP characterization	Develop simplified test methods for rapid RAP characterization without extracting binder.	A full-scale experiment to evaluate the suitability of two methods for characterization of RAP without extraction of binder.
Aging & Rejuvenators	Develop an aging protocol for mixture design to assess durability of rejuvenated RAP.	Laboratory-aging of asphalt to compare with plant produced mixes and road cores. Development of a procedure for evaluation of rejuvenator aging resistance.
Performance-based mix design	Develop of a procedure that would allow designing high RAP mixtures with similar performance and life cycle to the conventional asphalt.	Use a performance-based mixture to design the mixtures for test sections. Develop acceptance criteria for semi-circular bend and cyclic compression tests.
Test section in Uster	Evaluate full-scale production and paving of high RAP mixtures for high traffic roads.	Construction of a test section in Uster to validate the performance of polymer-modified mixtures with high RAP content.
Test section in Lukmanierpass	Evaluate full-scale production and paving of high RAP mixtures for high altitude roads.	Construction of a test section in Lukmanierpass to validate the performance of foundation and base course mixtures with high RAP content.

Publications

Project report	HighRAP full report
One-page summary	One-page summary (EN) One-page summary (DE)
Summary (11 pages)	Project Summary (EN) Project summary (DE) Project summary (FR)
Presentation	Summary presentation (EN) Summary presentation (DE)
Calculation tools	Calculator for optimization of RAP crushing and screening Calculator for determining effect of milling Calculator for determining the optimum rejuvenator dosage Calculator for determining the effect of RAP variability
Scientific publications	Asphalt recycling in polymer modified pavement: A test section and recommendations (EN) Three indexes to characterise crushing and screening of reclaimed asphalt pavement (EN) Impact of milling machine parameters on the properties of reclaimed asphalt pavement (EN) Performance-based design of asphalt mixtures and review of key parameters Other publications are planned
Press	Aus (Asph)alt mach neu, Empa Paving the Way for More Asphalt Recycling, NewsWise VIDEO: Empa tichtet teststrekce für Recycelten Asphalt ein, TeleZ Paving the way for more asphalt recycling, Swissinfo.ch