Within the European research project COREPASOL supported by a group of countries associated in the Conference of European Directors of Roads, the effect of distilled bitumen gained from different locations on the characteristics (indirect tensile strength, water susceptibility and stiffness) of cold recycled asphalt mixtures has been assessed as a partial task. In the first step, the optimum foaming water was evaluated for each bituminous sample by optimizing the relationship between the expansion rate and the half-time. For the optimized foaming water content, one cold recycled mix design with different foamed bituminous binders has been used. The behavior of all experimental mixes has been tested by indirect tensile strength test done after 7 and 14 days for cured specimens, whereas the curing procedure respected Czech technical specification TP208. In parallel, stiffness testing has been done for each mix variant and a group of specimens has been water soaked between 7th and 14th day. These specimens were used for water susceptibility testing. After the first set of tests has been done, two foaming agents were used for selected bitumen represented by additives provided by Iterchimica and MeadWestVaco. For bitumen doped by such agents, the foam characteristics were evaluated again with a distinctive improvement in both foam characteristics particularly for one of the agents. Also this foamed bitumen has been later used for cold recycled mix laboratory production and testing. This paper presents the results obtained and findings with recommendations.

cold recycling mixes, foamed bitumen, foaming agent, indirect tensile strength, stiffness modulus, water susceptibility