Creep Recovery Performance of Hydrated Lime (HL) and Limestone (LS) in RTFO Aged Asphalt Mastic

In an asphalt structure, mastic is the primary element that deforms. Many studies have been conducted to develop a rheological parameter that can assess the deformation and creep characteristics of asphalt mastic with varying proportions of fillers. However, only a few studies show the influence of Hydrated Lime (HL), Limestone (LS), and their combined effect (HL + LS) on the creep recovery performance of asphalt mastic with the combination of modifiers and anti-stripping agents. This paper employs the multiple stress creep recovery (MSCR) test as per AASHTO T 350 to understand the creep recovery properties of asphalt mastic. This study modified a neat PG 58-28 binder with Styrene–Butadiene–Styrene (SBS) or Gilsonite and Zycotherm as a liquid anti-stripping agent. Different filler-binder (F/B) ratios of HL, LS, and different proportions of HL + LS combined with SBS and Gilsonite modified binder containing Zycotherm were utilized to fabricate the asphalt mastic. Then, the Rolling Thin-Film Oven (RTFO) protocol was applied to simulate asphalt production time aging. The performance of these mastics was compared using non-recoverable creep compliance, stress sensitivity analysis, and MSCR percent recovery analysis. AASHTO M 332 specifications have been used to classify all the mastics based on the Jnr value at 3.2 kPa and stress sensitivity. In addition, polymer modification curves specified by the asphalt institute (AI) were employed to interpret the test results. According to the analysis of experimental data, the combined effect of 10% HL and 70% LS modified with SBS was observed to be predominant and satisfy all the creep recovery performance requirements.