Courard Luc, Rondeux Mélanie, Zhao Zengfeng, Michel Frédéric
Building Materials, Urban and Environmental Engineering, University of Liège, Allée de la découverte 9, 4000 Liège, Belgium.
Materials (Basel). 2020 Jul 5;13(13):2994. doi: 10.3390/ma13132994.
Fine recycled aggregates are produced in large quantities when crushing Construction and Demolition Waste (C&DW). Even if coarse recycled aggregates are commonly used for road foundations, fine particles are often rejected as they are considered detrimental for the long-term behaviour of foundations. Physicochemical, mineralogical and mechanical characterizations (through X-ray diffraction, X-ray fluorescence, the chloride and sulphate contents, Los Angeles abrasion, micro-Deval resistance and static plate load tests) were performed on raw and treated fine recycled materials for understanding both the effects of the preparation, the compaction and the freeze-thaw cycles on the properties and the evolution of fine particles. Special attention was provided to the shape analysis of fines by means of image analyser. The results showed that the main characteristic parameters to be considered are the sieving curve and the proportion of grades. The mixes containing the highest quantity of fine particles, specifically lower than 63 µm, usually inducing a higher water demand and a higher capillary rise. This can be explained by specific surface and bluntness parameters which increase with the finer particles, inducing a higher surface roughness and, consequently, a higher potential interaction with water. Compaction did not seem to have a major effect on the production of fines (despite some breakdown occurred during compaction) and on the shape of materials (the bluntness and convexity increased slightly, while the elongation values remained similar after the compaction process). The static plate load tests showed that bearing capacity is slightly lower than the specifications for the road foundation after compaction. However, the studied material could meet the maximum criteria for secondary roads foundation construction on the wear resistance criteria. Recycled aggregates from C&DW without sufficient quality could be blended with other aggregates to enable their usage for upper-level road foundation.
在破碎建筑拆除废物（C&DW）时会大量产生细再生骨料。即使粗再生骨料通常用于道路基层，但细颗粒往往被拒收，因为它们被认为对基层的长期性能有害。对原始和处理后的细再生材料进行了物理化学、矿物学和力学表征（通过X射线衍射、X射线荧光、氯化物和硫酸盐含量、洛杉矶磨耗试验、微德瓦尔耐磨试验和静态平板载荷试验），以了解制备、压实和冻融循环对细颗粒性能及演变的影响。特别通过图像分析仪对细颗粒进行了形状分析。结果表明，需要考虑的主要特征参数是筛分曲线和级配比例。含有最高数量细颗粒（具体低于63微米）的混合料通常会导致更高的需水量和更高的毛细上升。这可以用比表面积和钝度参数来解释，这些参数随着颗粒变细而增加，导致更高的表面粗糙度，从而与水有更高的潜在相互作用。压实似乎对细颗粒的产生（尽管压实过程中发生了一些破碎）和材料形状（钝度和凸度略有增加，而压实后伸长值保持相似）没有重大影响。静态平板载荷试验表明，压实后承载力略低于道路基层的规范要求。然而，所研究的材料在耐磨性标准方面可以满足二级道路基层施工的最高标准。质量不足的建筑拆除废物再生骨料可以与其他骨料混合，以便用于上层道路基层。
