Laboratory Investigation of Hydraulically Bound Mixtures for Road Foundations Made with Waste Foundry Sand and Steel Slags

The paper discusses an experimental study, conducted at the University of Padova Road Research Laboratory, of hydraulically bound mixtures for road foundations, with the aggregate skeleton fully composed by industrial wastes, as foundry sands and steel slags, used with different proportions. The laboratory investigation has been subdivided in a preliminary study of the physical-geotechnical properties of the two different industrial wastes, and in the following mechanical characterization of the hydraulic bound mixtures. The formulation of the mixes has been developed in terms of Proctor, compression and indirect tensile tests. At the end of the study the elastic modulus of the mixtures has been evaluated through ultrasonic tests, also at different curing periods. The satisfactory results (compression and indirect tensile strength at 7 days up to 5.34 MPa and 0.72 MPa respectively, depending on the mixtures type and the cement content), have met the main Italian Contract Specifications, so demonstrating the possibility to use industrial by-products as integral substitutes of the natural aggregates in the production of cement bound granular material for road foundations.