Investigation of viscoelastic fracture fields in asphalt mixtures using digital image correlation
Investigation of viscoelastic fracture fields in asphalt mixtures using digital image correlation
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DOI：
10.1007/s10704-017-0180-8
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发表时间：
2017-05-01
影响因子：
2.5
通讯作者：
Lambros, John
中科院分区：
文献类型：
--
作者：
Doll, Berangere;Ozer, Hasan;Lambros, John
在这项工作中，我们研究了沥青混合料的断裂行为，这是一种用于铺路应用的硬质集料(通常以碎石的形式)与石油基沥青粘结剂的非均质混合物。具体地说，我们研究了沥青混合料的断裂响应与加载速度、温度和再生含量的关系-后者主要用于取代骨料和粘结剂等原始材料。对从不同组成的混合料中获得的半圆形弯曲边裂纹试件进行了断裂试验，并用相机记录了断裂事件，以便进行数字图像相关(DIC)测量。DIC的空间分辨率约为40m/像素，测量了预先存在的缺口尖端周围的远场应变场和位移场。这里我们的重点是通过量化材料的粘弹性响应和断裂特性来表征材料的行为。利用弹性-粘弹性对应原理从全场DIC应变场和位移场中提取粘性分量和弹性分量。评估了除骨折本身以外的各种能量耗散机制。对远场应力应变响应和能量耗散进行了量化。然后用伪弹性应力强度因子研究了断裂性能，并量化了加载速度、温度和粘结剂中回收含量对断裂性能的影响。可以看出，材料的粘弹性特性是在室温下获得材料行为的主要因素。一般情况下，位移的弹性分量只占总位移的30%左右，这表明在这种状态下粘弹性的影响很大。加载速率、温度和再生沥青屋面板(RAS)掺量对粘性响应均有影响，随着加载速率或再生沥青墙板掺量的增加或温度的降低，会产生更多的弹性响应。从这些宏观测量中可以清楚地看出，RAS含量的增加显著地使材料变脆，产生的粘性效应和在远场中消耗的能量较少，几乎与加载速度增加(从6.25 mm/min到50 mm/min)或温度变化(-12到25℃)相关的减少相当。
In this work we have studied the fracture behavior of asphalt mixtures, a heterogeneous mix of hard aggregates (usually in the form of crushed quarried rock) with a petroleum based asphalt binder, used in paving applications. Specifically, we studied the dependence of asphalt mixes' fracture response on loading rate, temperature, and recycled content-the latter used primarily to replace virgin materials like aggregates and binder. Fracture tests were conducted on semi-circular bend edge cracked specimens obtained from mixes with different compositions, and the fracture event was recorded with a camera to allow for digital image correlation (DIC) measurements. DIC, with a spatial resolution of about 40 m/pixel, measured the far-field strain and displacement fields developing around a preexisting notch tip. Our focus here is on characterizing the material behavior by quantifying its viscoelastic response and fracture properties. The elastic-viscoelastic correspondence principle was used to extract viscous and elastic components from the full-field DIC-measured strain and displacement fields. Various energy dissipation mechanisms other than the fracture itself were evaluated. Stress-strain response and energy dissipated in the far-field regions were quantified. The pseudo-elastic stress intensity factor was then used to study the fracture properties, and quantify the effects on fracture properties of loading rate, temperature, and recycled content in the binder. It was seen that the viscoelastic characteristics of the material were a dominant factor in the material behavior obtained at room temperature. In general, the elastic component of the displacement was only up to about 30% of the total displacement, indicating a strong influence of viscoelasticity in this state. Loading rate, temperature and recycled asphalt shingles (RAS) content all affected the viscous response by introducing more elastic response when loading rate or recycled content increased or when temperature decreased. It became clear from these macroscopic measurements that the increase of RAS content considerably embrittles the material producing less viscous effects and less energy dissipated in the far-field, almost comparable to reductions associated with the loading rate increase (from 6.25 to 50 mm/min) or the temperature change (-12 to 25 degrees C).