Effects of Partial Substitution of Styrene-butadiene-styrene with Granulated Blast-furnace Slag on the Strength Properties of Porous Asphalt

The present experimental research investigates the feasibility of partial substitution of styrene-butadiene-styrene (SBS) with ground granulated blast-furnace slag (GGBS) for the modification of bitumen and porous asphalt mixtures. The control asphalt mixture and the seven modified porous asphalt mixtures have been analyzed separately and their performance was compared. Modified bitumen and asphalt mixtures were evaluated based on the penetration test, softening point, ductility, Marshall stability, indirect tensile strength (ITS), moisture susceptibility, uniaxial compression test, porosity, and permeability. According to the results, a blend of GGBS and SBS can be used to modify porous asphalt mixtures since it either improves or does not change their properties. The results show that using these additives have decreased penetration and ductility of bitumen and also there is an increase in softening point, so that the additives have strengthened asphalt mixture properties such as Marshall strength, ITS and Uniaxial compression strength. Furthermore, in the current research work,  artificial neural networks (ANN) are used to estimate the permeability of modified porous asphalt mixtures. Sensitivity analysis was discussed for the measurement of the importance of different input parameters. The laboratory experiments and proposed ANN model indicated that a new method can be developed for permeability control.