Introduction

COREPASOL project is part of the CEDR Transnational Road Research  Programme and is one of three projects funded under the Call 2012  Recycling programme.
The project is funded by the road administrations of Denmark, Finland,  Germany, Ireland, Netherlands, Norway: the programme is being managed on  behalf of CEDR by the National Roads Authority of Ireland.
The project Manager for the project is Finn Thogersen of the Danish Road  Directorate.

 

Expected yearly worldwide demand for road rehabilitation works concerns about 1.7 mil. km of roads. This creates on one hand large needs for natural resources used, on the other hand bears significant potential for reuse of existing pavement materials and focus on recycling techniques. Following the key characteristic of asphalt pavement being 100% recyclable, suitable techniques should be continuously developed and supported. Cold recycling can be seen as a technology where several benefits and added-value are linked – natural resources can be reduced, energy consumption decreased, road infrastructure protected from excessive construction-related transport and rehabilitation works can be shortened. Simultaneously, by this technology multiple recycling of already once recycled roads bears another potential and beneficial effects with similar advantages as described previously. The question is only rate of old binder activation. If proper mix design is applied and suitable binders used including activating the bituminous binder in reclaimed material new structure will lead to increased bearing capacity and improved pavement durability. Despite of these facts not more than 35 % of reclaimed asphalt is reused by cold recycling.

This project focuses mainly on harmonizing mix design of cold-recycled bitumen stabilized materials following the existing scientific and engineering experience and approaches. The key objective in this relation is to develop and recommend comprehensive mix design and characterization by studying compaction methods, curing procedures and performance tests. The output should be applicable to all variants of cold-recycled mixtures containing bituminous binders or combination with other binders or alternative fines. Aspects considerable for defining durability of cold-recycled mixtures will be evaluated and specified as well. The existing practice focuses only on water immersion and stiffness. Both characteristics are not a standard part in all mix designs known in Europe. Nevertheless to vindicate and promote cold recycling as an equivalent solution for hot mix asphalt the durability must be predictable. For this reason the project focuses on assessing stiffness, fatigue behaviour, resistance to cracking and on long-term moisture effects. Different test procedures will be evaluated and most suitable approach recommended including proposed threshold limits. This will make performance-based mix design possible. Further gained results will be used for formulating preferable inclusion of cold-recycled mixture in existing pavement design manuals. It is primarily not expected to modify the mechanistic calculation of pavement design, more important seems to be the definition of typical structures where cold-recycled bitumen stabilized materials are used for base or binder courses and critical parameters are defined. This should allow to road administrators and designer to use cold-recycled mixtures as a standard component of a pavement structure.

As has been stated above, multiple recycling should present one of the key advantages of cold recycling techniques. In this connection activity of reclaimed asphalt, impact of material ageing and range of applicability not only in cold-recycled mixtures but also as partial substitute of aggregates in hot mix asphalts will be specified and most suitable practice recommended. Last part of the project focuses on environmental stability/compatibility which becomes an integral part of building materials’ use and modern civil engineering. Leaching of cold-recycled mixtures will be specified with recommendations for threshold limits. At the same time some hazardous or problematic materials in existing pavements will be assessed in relation to their immobilization and most suitable reuse by cold recycling (tar, asbestos, crumb-rubber modified asphalt). Part of environmental stability will be devoted to technically correct assessment of cold-recycled mixtures with respect to their carbon footprint. It is believed, that in the near future such energy equivalent will be considered in decision about most appropriate technical solutions in pavement construction or rehabilitation and energy savings achievable by recycling should be considered as a benefit.

The project consortium bundles the capabilities of science, public interests and industrial knowledge to overcome the described problem and to offer an appropriate solution.