Laboratory Evaluation and Construction of Fully Recycled Low-Temperature Asphalt for Low-Volume Roads

Christiane Raab,Manfred N Partl

doi:10.1155/2020/4904056

Abstract

Growing economy and increasing pollution evoke the need for more environmentally friendly road construction techniques and the saving of natural resources. In this context, cold recycling plays an important role since, on the one hand, it allows to reduce CO2 emissions drastically and, on the other hand, it offers a variety of opportunities for high percentages of recycling. Inspired by experience in Sweden, the international project “Optimal Recycling of Reclaimed Asphalts for low-traffic Pavement” (ORRAP) for low-volume roads in the Upper Rhine region aims to develop and establish a new strategy for 100% reclaimed asphalt pavement (RAP) at ambient temperature (20°C) without adding virgin bituminous binders or rejuvenators. The still ongoing research project involves laboratory experiments as well as in situ test sections. The link between small-scale laboratory experiments and in situ testing is provided by medium-scale traffic simulation in the laboratory. This paper describes results from medium-scale compaction in the laboratory using different methods as well as traffic simulation with a medium-scale mobile traffic load simulator. The results show that compaction in the laboratory at ambient temperature (20°) is very difficult to achieve. Nevertheless, it was found that compaction at a temperature of 60°C appears possible and provides promising results regarding stability and rutting enabling the in situ construction. The in situ pavement construction at ambient temperature on a low-volume road in Switzerland resulted in a visibly well-compacted and stable base course which was covered by a hot mix asphalt surface course the day after. The test section will be monitored closely over the next 12 months.

Highlights

For environmental reasons, recycling of reclaimed asphalt pavement (RAP) has become mandatory in many countries and regions worldwide
Objective e objective of this paper is to present the results and conclusions of the medium-scale compaction evaluation in the laboratory with different compaction methods using different RAP materials provided by Switzerland, France, and Germany
It could be due to sudden reorientation and local breakage of RAP chunks that were unexpectedly large and concentrated on one side of the specimens. is would mean that these chunks did withstand the compaction process with the steel roller but not the repeated kneading loads of the pneumatic rutting wheel at 60°C

Summary

Introduction

For environmental reasons, recycling of reclaimed asphalt pavement (RAP) has become mandatory in many countries and regions worldwide. Is is true, in regions with high-standard infrastructures, dense population, and busy regional road networks, where rehabilitation by far dominates new construction. One of these regions is the Upper Rhine area, combining parts of Germany, France, and Switzerland between the cities of Karlsruhe, Strasbourg, and Basel. RAP is reused for both hot- and low-temperature asphalt mixtures by adding new material, either as single material components or as certain percentages of new asphalt mixture [1, 2]. Adding new material means that one can only get close to 100% recycling of RAP

Methods

Results

Conclusion