Evaluating the rutting potential of mastic and asphalt mixtures with precipitated calcium carbonate as a filler substitute

Rutting remains a primary distress in asphalt pavements, particularly under heavy traffic loading and elevated temperatures. To mitigate this phenomenon, utilising industrial by-products such as precipitated calcium carbonate (PCC) as a sustainable filler substitute offers a promising approach for enhancing durability. In this study, PCC was incorporated as a mineral filler replacement at dosages of 35%, 70% and 100% by weight. Material characterisation through X-ray fluorescence (XRF), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) methods revealed that PCC possesses high alkalinity (81.63% calcium oxide (CaO)) and a highly porous, cauliflower-like morphology with a significantly higher specific surface area (SSA) compared to conventional granite filler. Performance was evaluated at the mastic level using a dynamic shear rheometer (DSR) and multiple stress creep recovery (MSCR) tests, and at the mixture level via Marshall stability and dynamic creep tests. At the mastic level, PCC significantly enhanced the rutting factor and recovery percentage while reducing non-recoverable creep compliance; these improvements are attributed to the superior physical reinforcement – driven by the high SSA and porous morphology of PCC – coupled with robust chemical bonding between the alkaline filler and acidic bitumen. Regarding mixture performance, the incorporation of PCC increased the Marshall Quotient by approximately 40 %. Furthermore, dynamic creep tests revealed that 100% PCC replacement increased the flow number by 21% at 40 °C and 51% at 60 °C. These findings confirm that PCC optimises asphalt performance through a synergistic effect of enhanced interfacial adhesion and mechanical interlocking, providing a sustainable solution for high-performance pavement construction.