A new approach to determine absorption water of reclaimed asphalt pavement aggregate (RAP) for the production of cold recycled mixtures (CRM)

Abstract

Absorption ability of aggregates is one of the most important material characteristics in the perspective of a bituminous mixture mix design. In particular, this aspect gains more importance in the framework of cold recycled mixtures (CRM). Since such materials are produced at ambient temperature, the workability is ensured by the employment of bitumen emulsion and water. As a consequence, the water absorption of the aggregate phase needs to be clearly stated, in order to know the amount of effective water which will affect workability and mechanical properties of the mixtures. The determination of absorption water is clearly described in international standards (ASTM and European Standard). Nevertheless, both practices leave some aspects unclear, leading to misleading results if applied to the same material. In this paper, a new approach to determine the water absorption of reclaimed asphalt pavement (RAP) used to produce CRM is proposed. Results showed that both standards used in this work gave different absorption water values, making difficult to assess which one is reliable. The new approach highlighted the possibility to evaluate in a more precise and scientific way the absorption water of RAP aggregate, studying the volumetric changes at different water content under compaction.