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<p>The ageing process of asphalt binders reduces the lifespan of flexible pavements while causing stiffness related cracks that damage the structure. The effects of oxidative ageing on aggregates at the binder or mastic scale have received extensive research but studies are limited regarding oxidative ageing at the mixture level. This research investigates how aggregate selection and filler replacement with hydrated lime affects asphalt mixture ageing. Long-term ageing tests were conducted on asphalt concrete specimens made from granite and limestone aggregates with and without hydrated lime addition. This research analyzed the effects of using hydrated lime substitutes for 1% and 2% of aggregate weight on asphalt ageing behavior. The semi-circular bending (SCB), indirect tensile strength (ITS), and indirect tensile stiffness modulus (ITSM) tests were used to evaluate the mechanical performance of the specimens. A Dynamic Shear Rheometer (DSR) and Fourier Transform Infrared Spectroscopy (FTIR) were used to perform rheological and chemical analyses on the recovered binders. Results show that 2% hydrated lime replacement improved stiffness modulus of granite mixtures by up to 40%, and limestone mixtures by up to 20%. Fracture toughness (SCB test) after ageing at 20&#xa0;°C increased by up to 15% with hydrated lime addition, while hydrated lime reduced the ITS ageing index by approximately 10–18% compared to mixtures without lime. Bitumen binders recovered from granite mixtures containing hydrated lime were up to 18% softer (lower ageing indices) than those with only granite filler. FTIR analysis also showed that carbonyl and sulfoxide ageing indices were reduced by up to 12%, confirming the effectiveness of hydrated lime in slowing oxidation. These findings demonstrate that hydrated lime enhances long-term performance and ageing resistance of asphalt mixtures, particularly those with granite aggregate.</p>

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Effect of aggregate type and hydrated lime on long-term ageing of asphalt mixtures

  • 期刊论文

  • 发表日期：

    2025年7月19日

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  • Syed Bilal Ahmed Zaidi,
  • Rami M. Alfaqawi,
  • Hafiz Ammar Zahid,
  • Gordon D. Airey,
  • James Grenfell

摘要

The ageing process of asphalt binders reduces the lifespan of flexible pavements while causing stiffness related cracks that damage the structure. The effects of oxidative ageing on aggregates at the binder or mastic scale have received extensive research but studies are limited regarding oxidative ageing at the mixture level. This research investigates how aggregate selection and filler replacement with hydrated lime affects asphalt mixture ageing. Long-term ageing tests were conducted on asphalt concrete specimens made from granite and limestone aggregates with and without hydrated lime addition. This research analyzed the effects of using hydrated lime substitutes for 1% and 2% of aggregate weight on asphalt ageing behavior. The semi-circular bending (SCB), indirect tensile strength (ITS), and indirect tensile stiffness modulus (ITSM) tests were used to evaluate the mechanical performance of the specimens. A Dynamic Shear Rheometer (DSR) and Fourier Transform Infrared Spectroscopy (FTIR) were used to perform rheological and chemical analyses on the recovered binders. Results show that 2% hydrated lime replacement improved stiffness modulus of granite mixtures by up to 40%, and limestone mixtures by up to 20%. Fracture toughness (SCB test) after ageing at 20 °C increased by up to 15% with hydrated lime addition, while hydrated lime reduced the ITS ageing index by approximately 10–18% compared to mixtures without lime. Bitumen binders recovered from granite mixtures containing hydrated lime were up to 18% softer (lower ageing indices) than those with only granite filler. FTIR analysis also showed that carbonyl and sulfoxide ageing indices were reduced by up to 12%, confirming the effectiveness of hydrated lime in slowing oxidation. These findings demonstrate that hydrated lime enhances long-term performance and ageing resistance of asphalt mixtures, particularly those with granite aggregate.