Hot Mix Asphalt with High RAP Content

AbstractDue to increasing cost of asphalt binder, significant economic savings can be realized using high content of reclaimed asphalt pavement (RAP) in the production of new hot mix asphalt (HMA). Moreover, this is an environmentally friendly alternative as it reduces the need for virgin materials. It has to be noted that in Latvia RAP is rarely used in production of HMA and this valuable material is mostly degraded for use in lower value applications. Three mixtures were designed, which were the combination of two different RAP sources and local dolomite aggregates. The RAP binder had significantly aged having penetration of around 38mm, softening point of 56°C and Fraass temperature of -10°C. RAP was added at rates 30% and 50% for each RAP source. A softer binder grade (70/100 versus traditional 50/70) was added to compensate for the aged RAP binder. Hamburg wheel tracking test results demonstrated that all mixtures have high rutting resistance and fatigue test results using four-point bending beam were similar to those of virgin mixture. This demonstrated that mixtures with high RAP content can be successfully designed to meet the local volumetric and performance-specification requirements

Complex Optimization of Heavy Duty Asphalt Pavement Types in DURABROADS Project

DURABROADS, an EU FP7 financed project launched in 2013, and led by the University of Cantabria (Spain) aims at providing a sustainable growth through the development of innovative, cost-effective and more durable pavements. The new generation of pavement is based on innovative eco-friendly nanotechnology-enhanced asphalts as well on the optimization of procedures to build and rehabilitate durable, safer and greener road infrastructure more adapted to climate change and freight corridor traffic loads. One of the objectives of this project is to identify and evaluate the existing constraints concerning currently used road materials of heavily trafficked roads (TEN-T routes) to withstand current road challenges. Due to different traffic and climate features, four European regions (Northern, Central, Western and Southern Europe) were differentiated. The climate change elements critical to various road types were identified, reviewing the pavement deterioration forms they accelerate. The traffic loads on freight corridors were evaluated considering their accelerated pavement deterioration forms. The synergistic effect of extreme climatic and mechanical loads to pavement surface was scrutinised. A comprehensive quantification methodology for extreme traffic and climatic load combinations was suggested including technical (functional), economic, environmental and social-human aspects with appropriate weighing. Then the European region-specific ?optimal? asphalt wearing course types and road rehabilitation techniques for TEN-T routes were identified. The region-specific material and procedure optimization utilizes ? in addition to the processing of a comprehensive literature survey ? the answers coming from 81 experts of 52 European institutions to targeted questionnaire. These data were used to develop a decision support model based on AHP and TOPSIS models to facilitate the selection of asphalt pavement types. The results suggested Stone Mastic Asphalt (SMA) as the most suitable alternative in different climate change scenarios evaluated by a sensitivity analysis.This paper was possible thanks to the research project DURABROADS financed by the European Commission through the Seventh Framework Programme for Research (FP7). The authors also wish to express their gratitude to the panel of experts that contributed to enrich the quality of this paper through their valuable contribution