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Evaluating the crushing characteristics of recycled construction and demolition waste for use in road bases
Transportation Geotechnics ( IF 5.3 ) Pub Date : 2021-03-16 , DOI: 10.1016/j.trgeo.2021.100543
Hua-Lin Zhang , Yao Tang , Tao Meng , Liang-Tong Zhan

With the increasing production of construction and demolition waste (CDW), the use of CDW as a road base has become a sustainable and eco-friendly disposal approach. The aggregate crushing value is an essential index in the construction of road bases and is defined as the mass percentage of fine particles after a confined compression test of recycled CDW. In this study, experiments and numerical simulations were conducted to evaluate the crushing characteristics of the CDW, consisting of three main components, i.e., gravel, brick, and mortar. From the single-particle crushing tests, the gravel was strongest, and the mortar was weakest. Multi-particle confined compression tests showed that the load–displacement curves of the recycled aggregates exhibited an increasing trend. The fluctuations during loading were attributed to the particle breakage. A three-dimensional discrete element method (DEM) with a laser scanning and reconstruction technique was proposed to model irregular-shaped aggregate particles using a cluster of bonded particles. A comparison of the experimental and numerical results showed that the bond breakage ratio linearly increased with the aggregate crushing value, providing a quantitative linkage between the micro-scale numerical model and the macro-scale test. It was found that the volume proportion of the gravel significantly affected the mechanical behavior of the mixed aggregates, and 75% was the critical threshold of the gravel component. As gravel with a volume proportion from zero to 75% was added to the brick or mortar, the aggregate crushing value increased by only 10–15%. In the mixed aggregates with brick and gravel, more of the brick particles were crushed when gravel with a proportion of 50–75% was added due to inconsistent deformation and stress concentration. If the gravel proportion exceeded 75%, the aggregate crushing value was reduced by 30%. Based on the numerical and experimental investigations of the crushing characteristics of the recycled aggregates, a ternary diagram was proposed to design the proportion of the three components in recycled CDW for road bases.



中文翻译:

评估用于路基的再生建筑和拆除废物的破碎特性

随着建筑废料和拆除废物(CDW)产量的增加,将CDW用作路基已成为一种可持续且环保的处置方法。总压碎值是路基建设中的一项重要指标,并定义为经过循环再利用的CDW的压缩试验后细颗粒的质量百分比。在这项研究中,进行了实验和数值模拟以评估CDW的破碎特性,其由砾石,砖和砂浆三个主要成分组成。从单颗粒破碎测试来看,砾石最强,而砂浆最弱。多颗粒约束压缩试验表明,再生骨料的载荷-位移曲线呈上升趋势。加载过程中的波动归因于颗粒破损。提出了一种采用激光扫描和重建技术的三维离散元方法(DEM),以使用键合粒子簇对不规则形状的聚集粒子进行建模。实验和数值结果的比较表明,结合物破碎率随骨料破碎值的增加而线性增加,从而在微观模型和宏观试验之间建立了定量联系。发现砾石的体积比例显着影响混合骨料的力学性能,其中75%是砾石成分的临界阈值。当将体积比从零到75%的砾石添加到砖或灰浆中时,碎石总值仅增加了10%至15%。在混有砖石的骨料中,由于不一致的变形和应力集中,当添加碎石的比例为50–75%时,更多的砖颗粒被压碎。如果砾石比例超过75%,则骨料破碎值将降低30%。在对再生骨料的破碎特性进行数值和实验研究的基础上,提出了三元图设计路基再生CDW中三种成分的比例。

更新日期:2021-03-31
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