Cold recycled asphalt for pavements with optimized resource and energy efficiency: proposal for harmonized mix and pavement design

The analysis of national specification documents on mix design for cold recycled materials (CRM) resulted in the proposal of a 7-step approach for optimizing the mixture composition. This procedure contains recommendations for sampling (1) and assessment (2) of reclaimed asphalt, design of the mix granulate grading (3) by adding fine natural aggregates, assessment of the water content (4), selection of bitumen emulsion and additional mineral binders (5), preparation of CRM mix and compaction and curing of specimens (6) and finally the prove of void content, strength and water sensitivity (7). For 17 existing flexible pavements with CRM base layers throughout Europe, a common pavement design strategy could be observed resulting in a durability similar to expectations on usual flexible pavements composed of hot-mix asphalt (HMA). A simplistic pavement design procedure is proposed.