Mechanical characterisation of cold recycled mixtures

Among the various rehabilitation techniques of road pavements, cold recycling with foamed bitumen and cement represents one of the most promising options, both in technical, economic and environmental terms. Although the general principles of this technology are now well-defined, some composition and performance aspects of the mixtures have not yet been sufficiently investigated, as for example the optimum content of both the bitumen and hydraulic binder and the mechanical behaviour after dynamic stresses. The paper presents the results of an investigation carried out at the Road Research Laboratory of the University of Padova to determine the optimum bitumen/cement ratio of mixtures containing the same percentages of milled material and virgin aggregate, and to verify their performance in terms of Marshall Stability, Indirect Tensile Strength and Stiffness Modulus (which has been determined on a wide range of frequencies and temperatures).