Mix design and mechanical evaluation of hydraulically bound mixtures made with waste foundry sand and steel slags

The paper describes an experimental study concerning the use of hydraulically bound mixtures for roads and highways foundations, with the aggregate skeleton fully composed by industrial by-products, as foundry sands and steel slags, used with three different proportions. The laboratory investigation involved a preliminary study of the physical-geotechnical properties of the two different marginal materials and, then, the formulation of the hydraulic mixtures by means of Proctor, compression and indirect tensile tests, at short as well as medium curing periods. In order to get a deeper mechanical characterization, the elastic modulus of the mixtures has been evaluated through static and dynamic tests, both at different curing times. Because the requisites for acceptance in the Italian Specifications and Standards have been satisfied and given the positive mechanical performance of the mixes (compressive strength and indirect tensile strength at 28 days up to 7.4 MPa and 0.68 MPa respectively, depending on the mixtures type and the cement content), it has been verified that the industrial wastes analyzed in the study, can be used as integral substitutes of the natural aggregates, in the production of cement bound mixtures for pavements foundations.