Performance evaluation of asphalt mixtures and mastics containing precipitated calcium carbonate filler: Fatigue resistance at intermediate temperatures

Fatigue cracking remains a primary structural distress in asphalt pavements, necessitating the exploration of high-performance modifiers to enhance durability. This study investigates the multi-scale fatigue behavior of asphalt mixtures and mastics modified with Precipitated Calcium Carbonate (PCC) filler. A comprehensive experimental program was conducted, employing Indirect Tensile Fatigue (ITF) tests for mixtures and Linear Amplitude Sweep (LAS) tests for mastics at various PCC replacement levels (0%, 35%, 70%, and 100%) and temperatures (10 °C and 20 °C). To explore the potential underlying mechanisms, cohesive and adhesive bond strength tests were performed. Results indicate that the incorporation of PCC can extend the fatigue life of both asphalt mastics and mixtures while reducing their stress sensitivity. Phenomenological modeling suggests that increasing PCC content tends to optimize fatigue parameters at both scales; for instance, the fatigue slope (K 2 ) of the mixtures shifted toward zero (e.g., from -1.252 to -1.014 at 10 °C), reflecting a trend toward enhanced structural robustness. Simultaneously, LAS test results revealed an improvement in mastic fatigue endurance across the replacement levels, with statistical validation via t-tests supporting the significance of these performance gains (p-value < 0.001). Mechanistically, strong second-order polynomial correlations (R 2 > 0.96) were observed between cohesive/adhesive bond strengths and the fatigue endurance of both mastics and mixtures. The high specific surface area of PCC particles is thought to promote physicochemical interactions with the bitumen, potentially pinning micro-cracks and increasing the energy threshold for crack propagation. Notably, a strong correlation (R 2 = 0.9572) was identified between mastic and mixture fatigue lives, suggesting that mastic-scale testing may serve as a valuable preliminary screening indicator for evaluating bulk mixture fatigue trends. This research suggests that PCC holds promise as a effective and sustainable modifier for potentially extending the service life of pavement structures.