<p>The primary objective of this study is to recover the performance of the recycled binders/mixtures incorporating Reclaimed Asphalt Pavement (RAP)—under three distinct cases: 40%RAP, 60%RAP and a hybrid case with RAP from two sources—to the level of the virgin material, relying on the application of green softening oils (including two bio-oils and refined engine oil bottom (REOB)). Prior to blending with RAP binders, the softening oils were first introduced to the base binder to evaluate their effectiveness on the Performance Grade (PG) of the base binder, meanwhile an oil modification index (OMI) was derived to quantify the efficiency of each oil in modifying both high- and low- temperature PG. Single Edge Notched Beam (SENB) tests were further employed to assess the oils’ effects on cracking property of binders beyond the linear viscoelastic range. Then, the oil contents were determined for each RAP recycling case to achieve cracking performance restoration targets aligned with the base binder, based on combined PG and SENB outcomes. Finally, the recycled binder and mixture samples prepared with the oil at the determined content were subjected to PG, PG plus, and Indirect Tensile Asphalt Cracking (IDEAL-CT) tests to evaluate binder and mixture performance, respectively. The findings highlight that two bio-oils outperform REOB in terms of improving both fatigue and thermal cracking performance, from both perspectives of binder and mixture, indicating that bio-oils may be more suitable in high RAP recycling scenarios.</p>

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Application of green softening oil in RAP recycling with variable aged binders: oil effect, oil content determination and performance evaluation

  • Jing Xu,
  • Youlai Zhong,
  • Ronghua Gu,
  • Yuquan Yao,
  • Xiaoyong Tan,
  • Xilan Yu,
  • Bin Liu

摘要

The primary objective of this study is to recover the performance of the recycled binders/mixtures incorporating Reclaimed Asphalt Pavement (RAP)—under three distinct cases: 40%RAP, 60%RAP and a hybrid case with RAP from two sources—to the level of the virgin material, relying on the application of green softening oils (including two bio-oils and refined engine oil bottom (REOB)). Prior to blending with RAP binders, the softening oils were first introduced to the base binder to evaluate their effectiveness on the Performance Grade (PG) of the base binder, meanwhile an oil modification index (OMI) was derived to quantify the efficiency of each oil in modifying both high- and low- temperature PG. Single Edge Notched Beam (SENB) tests were further employed to assess the oils’ effects on cracking property of binders beyond the linear viscoelastic range. Then, the oil contents were determined for each RAP recycling case to achieve cracking performance restoration targets aligned with the base binder, based on combined PG and SENB outcomes. Finally, the recycled binder and mixture samples prepared with the oil at the determined content were subjected to PG, PG plus, and Indirect Tensile Asphalt Cracking (IDEAL-CT) tests to evaluate binder and mixture performance, respectively. The findings highlight that two bio-oils outperform REOB in terms of improving both fatigue and thermal cracking performance, from both perspectives of binder and mixture, indicating that bio-oils may be more suitable in high RAP recycling scenarios.