Blast furnace slag as a substitute for the fine fraction of aggregates in an asphalt mixture

Blast furnace slags (BFS) have interesting physical properties and chemical compositions for the production of mastics in asphalt mixtures. However, most of the studies conducted on this material and their applications in asphalt mixtures have been as substitutes for the coarse fraction of natural aggregates (NGA). In the present study, an experimental program was devised to evaluate the effect on the resistance of a hot mix asphalt (HMA), due to the replacement of fine fraction of a NGA by a BFS. The mechanical properties investigated were indirect tensile strengths, resilient modulus, permanent deformation, resistance to fatigue, and moisture damage. Analysis of variance (ANOVA) tests were performed to verify or reject the null hypothesis that the results are statically equal to those of the reference mixture. X-ray diffractometry (XRD) and X-ray fluorescence (XRF) tests were carried out on particles of BFS and NGA. Additionally, the samples were subjected to imaging processing in a scanning electron microscope (SEM). Characterization tests (viscosity, softening point, penetration, and indirect tension) were performed on mixtures made of fine particles (NGA and BFS) and asphalt. The BFS used as fine aggregate tends to generate, in conjunction with asphalt, a material with improved properties of resistance under monotonic and dynamic load.