Analysis of MSCR test results for asphalt binders with improved accuracy
Analysis of MSCR test results for asphalt binders with improved accuracy
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DOI：
10.1617/s11527-021-01691-0
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发表时间：
2021-04-01
影响因子：
3.8
通讯作者：
Samarai, Mufid
中科院分区：
文献类型：
--
作者：
Liu, Hanqi;Zeiada, Waleed;Samarai, Mufid
多应力蠕变恢复（MSCR）试验被认为是评价沥青结合料高温性能的最佳试验方法。然而，最近的研究表明，9秒的恢复时间可能不允许一些改性沥青结合料的粘弹性应变的完全恢复。在这种情况下，一些潜在的粘弹性恢复被错误地报告为未恢复应变，导致低估了沥青结合料的抗车辙能力。为了解决不完全恢复的问题，本文开发了一种机理建模方法来分析六种类型的沥青结合料的MSCR测试结果。在使用力学建模方法之前，首先确定所有沥青结合料在每个应力水平下的稳态应变响应。发现三种纯沥青结合料从最后10个循环开始达到稳态条件，而SBS改性的沥青结合料在最后5个循环中达到相对稳态。然后，基于Boltzmann叠加原理和Schapery非线性粘弹性理论，采用力学建模方法分析了各应力水平下最后5个循环的剪切应变数据。利用恢复部分末端的粘塑性应变和蠕变部分末端的粘弹性应变计算不可恢复蠕变柔量和恢复百分比。结果表明，在这项研究中采用的方法是能够分析的沥青结合料的MSCR测试结果，提高了准确性。
The multiple stress creep recovery (MSCR) test has been regarded by many as the best available test method to evaluate the high-temperature performance of asphalt binders. However, recent studies have shown that the 9-s recovery time may not allow a full recovery of viscoelastic strain for some modified asphalt binders. In that case, some potential viscoelastic recovery is mistakenly reported as unrecovered strain, leading to an underestimation of the asphalt binder rutting resistance. In order to address the issue of incomplete recovery, this paper developed a mechanistic modeling approach to analyze the MSCR test results of six types of asphalt binders. Before using the mechanistic modeling approach, the steady-state strain response at each stress level was firstly determined for all asphalt binders. It was found that the three neat asphalt binders reached a steady-state condition from the beginning of the last 10 cycles, whereas the SBS-modified asphalt binders reached a relatively steady state in the last 5 cycles. Afterwards, a mechanistic modeling approach was employed to analyze the shear strain data in the last 5 cycles at each stress level based on the Boltzmann superposition principle and the Schapery's nonlinear viscoelastic theory. The viscoplastic strain at the end of the recovery portion and the viscoelastic strain at the end of the creep portion were utilized to calculate the non-recoverable creep compliance and percent recovery. It was demonstrated that the approach adopted in this study was capable of analyzing the MSCR test results of asphalt binders with improved accuracy.