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Critical Behavior of Asphalt Mixtures Undergoing Glass Transition and Physical Hardening.

机译：经历玻璃化转变和物理硬化的沥青混合料的临界行为。

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摘要

In this study a device was developed that simultaneously tests two asphalt mixture beams; one unrestrained, and the other with restrained ends. The unrestrained beam is used to measure the one dimensional change of length with temperature, and consequently the glass transition temperature (Tg) and coefficients of expansion/contraction above and below the Tg. The restrained beam is used to capture the induced thermal stress buildup due to prevented contraction in the sample. The device, referred to as the Asphalt Thermal Cracking Analyzer (ATCA), was used to show how asphalt mixtures undergo isothermal contraction and physical hardening, and the consequences of this behavior for the buildup of thermal stress. A prediction model for the rate of physical hardening at different temperatures and conditioning times was developed based on a creep viscoelastic model, and was used to predict changes in binder stiffness and relaxation rate during isothermal conditioning. The model was then extended to mastics and a conversion factor was derived to shift results for applicability to asphalt mixture thermal strain calculation.;The physical hardening model of binders was coupled with relaxation modulus master curves and glass transition measurements to propose a model for the calculation of thermal stress buildup in mixtures as a continuous function of conditioning time and temperature. The model was validated using an elaborate set of experimentally derived input properties for a number of mixtures at different cooling rates.;An experimentally calibrated multiphase micro-mechanical model for asphalt mixture undergoing thermal shrinkage and glass transition was also developed in a finite element platform. The results where compared to experimental data measured using the ATCA device, which allowed measuring strain and stress build up during cooling.;The results of this study indicate that physical hardening of binders has important effects on the thermal stress and thermal strain accumulation in mixtures during cooling cycles. Failure to consider this time dependent behavior, which varies among binders, could lead to failure in predicting performance. The existing modulus and strain used in predicting thermal cracking of asphalt pavements need revisions to integrate a function for the time dependent changes.
机译：在这项研究中，开发了一种可以同时测试两个沥青混合料梁的设备。一个不受约束，另一个具有约束的目的。无约束光束用于测量长度随温度的一维变化，并因此测量玻璃化转变温度（Tg）以及高于和低于Tg的膨胀/收缩系数。由于防止了样品中的收缩，限制束用于捕获诱导的热应力累积。该设备被称为沥青热裂纹分析仪（ATCA），用于显示沥青混合物如何经历等温收缩和物理硬化，以及这种行为对热应力积累的影响。基于蠕变粘弹性模型，开发了在不同温度和条件下的物理硬化速率的预测模型，并用于预测等温条件下粘合剂的刚度和松弛率的变化。然后将该模型扩展为胶泥，并导出转换因子以转换结果，以适用于沥青混合料的热应变计算。;粘合剂的物理硬化模型与弛豫模量主曲线和玻璃化转变测量相结合，提出了计算模型混合物中的热应力积聚是调节时间和温度的连续函数。该模型使用一组复杂的实验得出的输入特性对不同冷却速率下多种混合物的模型进行了验证。在有限元平台上，还开发了一种经过实验校准的沥青混合物经历热收缩和玻璃化转变的微力学模型。将结果与使用ATCA设备测量的实验数据进行比较，可以测量冷却过程中的应变和应力。;这项研究的结果表明，粘合剂的物理硬化对混合物中的热应力和混合物中的热应变积累有重要影响冷却循环。如果不考虑这种依赖于时间的行为（绑定程序之间会有所不同），可能会导致无法预测性能。预测沥青路面热裂化所使用的现有模量和应变需要修订，以整合随时间变化的函数。

著录项

  • 作者

    Tabatabaee, Hassan Ali.;

  • 作者单位

    The University of Wisconsin - Madison.;

  • 授予单位 The University of Wisconsin - Madison.;
  • 学科 Applied Mechanics.;Engineering Civil.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:43:32

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