Experimental investigation on foamed bitumen bound mixtures made with marginal aggregates

The paper reports the results of a study, carried out at the Experimental Road Laboratory of the University of Padova, on foamed bitumen bound mixtures for road foundations, characterized by a stone skeleton made exclusively with 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 articulated in a laboratory evaluation of the physical, chemical and toxicological properties of each recycled and “artificial” aggregate and in the following mix design of the foamed bitumen bound mixtures, by means of indirect tensile strength, stiffness modulus and fatigue tests. The indirect tensile strength tests have been also performed on wet samples, in order to analyse the moisture resistance of the mixes. The positive results of the experimental investigation have demonstrated that the marginal aggregates analysed are completely suitable for totally replacing natural aggregates, for the production of foamed bitumen bound mixtures in the road construction.