Foamed Bitumen Bound Mixtures made with Marginal Aggregates: An Experimental Study

The paper describes a laboratory investigation on foamed bitumen bound mixtures for road foundations, with the aggregate matrix completely composed of industrial by-products, i.e. steel, blast furnace and ladle slags, bottom ash, coal ash and glass wastes, used with different proportions. The study has been organized in a laboratory analysis of the physical and chemical properties of the single re-cycled granular materials considered and in the following mechanical characterization of the foamed bitumen bound mixtures, in terms of indirect tensile strength, stiffness modulus and fatigue tests. The indirect tensile strength tests have been also performed in wet conditions, in order to investigate the moisture sensitivity of the mixes. The satisfactory results of the tests have demonstrated that the marginal materials considered are suitable for being used as integral substitutes of the natural aggregates, in the production of foamed bitumen bound mixtures.