Prediction and correction of asphalt mastic modulus based on effective volume fraction and filler–asphalt interaction

• A modulus correction model based on effective volume fraction is developed. • The model enhances prediction accuracy for mastics with high filler content. • Smaller fillers show stronger asphalt interaction and higher stiffening effects. This study explores the micromechanical prediction of asphalt mastic modulus and introduces a correction based on effective volume fraction to account for filler–asphalt interactions. Mastics with different filler contents and particle sizes were tested using a dynamic shear rheometer. The Mori–Tanaka model showed good agreement at low filler levels but underestimated modulus at higher contents due to ignored interfacial and particle–particle effects. To address this, an effective volume fraction model incorporating an equivalent rigid layer was proposed. Results showed a critical filler volume fraction around 44%, beyond which particle interactions dominate stiffening. Smaller particles led to greater modulus increases due to higher surface area and interaction intensity, while larger particles had weaker interactions and were better described by mechanical reinforcement alone. This work improves micromechanical modeling accuracy for asphalt mastics, providing practical insights for mix design in pavement engineering.