Influence of scallop shell powder and steel powder on the mechanical performance of asphalt mixtures: experimental study and FEM modeling

Abstract

This research evaluated the influence of scallop shell powder (passing #100 mesh) and steel powder (passing #200 mesh) on the mechanical and structural performance of hot mix asphalt, using an integrated experimental-numerical approach. Four mix designs were created using the Marshall method (75 blows per face): a conventional mix (M0) and three modified mixes with 5%, 10%, and 15% combined substitution. The optimum asphalt content, stability, flow, volumetric parameters (VIM, VMA, VFA), moisture resistance (TSR), and dynamic modulus at 20 °C were determined. The results showed that the 10% dosage exhibited the best overall performance, achieving a Marshall stability of 10.42 kN, representing a 17% increase compared to the conventional mix. The TSR index increased to 89%, exceeding the MTC regulatory requirement (≥ 80%), demonstrating improved binder-aggregate adhesion attributed to the calcitic nature of the shell dust. The dynamic modulus increased by approximately 14%, from 4500 MPa to 5150 MPa. Three-dimensional modeling using the finite element method allowed for the quantification of stress redistribution in the multilayer system. The optimal mix reduced surface deformation by approximately 15% and tensile stress at the base of the pavement by 16%, compared to the conventional mix. Under a 20% overload, structural amplification decreased from 38% to 25%, reducing sensitivity to vehicle overload. The results confirm that the controlled incorporation of scallop shell dust and steel powder simultaneously improves the mechanical stability, moisture resistance, and structural response of flexible pavement, constituting a technically viable alternative for conditions representative of Cajamarca.