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Permanent deformation analysis of base layers with recycled material: Effect of density and stress level
Transportation Geotechnics ( IF 4.9 ) Pub Date : 2020-11-13 , DOI: 10.1016/j.trgeo.2020.100466
Jean-Pascal Bilodeau , Erdrick Leandro Perez Gonzalez

Full-depth reclamation techniques present numerous advantages for pavement rehabilitation strategies. The recycling process produces a thick layer of stabilized or unstabilized reclaimed materials, which is used as a new base layer of RAP aggregates. The compaction of the unstabilized thick layer is critical for adequate permanent deformation behaviour of the reclaimed layer. In some agencies, the smooth drum compaction is often used directly after the recycling process to compact the reclaimed materials. Previous studies demonstrated the challenges associated with adequate densification of the thick reclaimed layer through its whole thickness, leaving among other a material with a vertical density gradient. In that context, this study was designed to quantify the effect of the degree of compaction on the permanent deformation behaviour using cyclic triaxial tests. Granite and limestone aggregates were mixed with RAP in order to obtain mixes with 50% RAP, and each blend was tested using a permanent deformation test procedure at four different degree of compaction. One of the tested degree of compaction was a varying compacted density over the sample height. It was found that the analysis of this particular sample performance could be done on the basis of the average dry density of the sample. The shakedown ranges of each sample were analyzed with respect to stress ratio and degree of compaction. The behaviour for each type of mix was also similar. A generalized model was therefore proposed allowing to predict the range of permanent deformation behaviour knowing stress level and the degree of compaction. The general model between shakedown range and a relative stress ratio is based on a shift factor linking the effect of stress and density. Limit states were also defined for the possible ranges of behaviour with respect to the degree of compaction.



中文翻译:

具有再生材料的基础层的永久变形分析:密度和应力水平的影响

全深度开垦技术为路面修复策略提供了众多优势。再循环过程会产生厚厚的稳定化或不稳定化回收材料,该层可用作RAP骨料的新基础层。未稳定的厚层的压实对于再生层的足够的永久变形行为至关重要。在某些机构中,通常在回收过程之后直接使用平滑的滚筒压实来压实回收的材料。先前的研究表明,在厚的再生层的整个厚度上进行充分的致密化会带来挑战,而剩下的则是具有垂直密度梯度的材料。在这种情况下,本研究旨在使用循环三轴试验量化压实度对永久变形行为的影响。将花岗岩和石灰石骨料与RAP混合以获得含50%RAP的混合物,并使用永久变形测试程序在四种不同的压实度下测试每种混合物。测试的压实度之一是在样品高度上变化的压实密度。已经发现,可以基于样品的平均干密度对这种特定的样品性能进行分析。就应力比和压实度分析了每个样品的击落范围。每种混合类型的行为也相似。因此,提出了一个通用模型,该模型可以在知道应力水平和压实度的情况下预测永久变形行为的范围。减震范围和相对应力比之间的通用模型基于将应力和密度影响联系在一起的位移因子。还针对压紧程度的可能行为范围定义了极限状态。

更新日期:2020-11-21
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