Comparative Study of the Mechanical Behaviour of Bitumen- and Cement-Dominated Mixtures with Reclaimed Asphalt

The bitumen emulsion-based recycling is a commonly used maintenance treatment in the rehabilitation of low-and medium-volume roads in Europe. Nevertheless, the wide range of climatic conditions across the continent resulted in the variety of mixture concepts and the requirements being adopted for various local conditions. In this regard, the most commonly used parameter to distinguish between the main mixture concepts is bitumen to cement ratio. This article presents the comparison of the results of mechanical properties for different approachest to design of cold recycled mixtures with either bitumen or cement having the dominant role in the mechanical behaviour. In both cases, bitumen emulsion C60B5 and Portland cement CEM I were used as binding agents, and the considered cold recycled mixtures were designed to contain at least 70 % of reclaimed asphalt. The combinations of binding agents were selected based on the respective requirements. Mechanical properties were expressed by the indirect tensile strength, failure strain, and stiffness modulus, while the tests were conducted at the temperatures of 5 and 20 °C and the curing periods of 7 and 28 days. The comparison showed that the mixtures with the higher content of cement reached much higher stiffness and, from the aspect of the kinetics of mechanical properties development, they almost resembled cementitious materials. In contrast to this, the behaviour of bitumen-dominated mixtures, especially at earlier curing stages, was within the common requirements but also tended to have much higher strains at failure.