Gabryś Katarzyna, Šadzevičius Raimondas, Dapkienė Midona, Ramukevičius Dainius, Sas Wojciech
SGGW Water Centre, Warsaw University of Life Sciences-SGGW, 02787 Warsaw, Poland.
Institute of Hydraulic Engineering, Vytautas Magnus University Agriculture Academy, 53361 Kaunas, Lithuania.
Materials (Basel). 2023 Jul 13;16(14):4986. doi: 10.3390/ma16144986.
The literature confirms that fine recycled concrete aggregate (fRCA) can be used as a replacement for natural soil in new concrete, offering many advantages. Despite these advantages, there are also critical barriers to the development of fRCA in new mixes. Among these, the first challenge is the variability of fRCA properties, in both physical, chemical, and mechanical terms. Many individual studies have been carried out on different RCA or fRCA properties, but little investigative work has been performed to analyze their dynamic properties. Therefore, the influence of the non-cohesive fine fraction content of RCA on the dynamic properties of this waste material, when used as a specific anthropogenic soil, has been studied in laboratory conditions, employing a standard resonant column apparatus, as well as piezoelectric elements. In the present research, special emphasis has been placed on the dynamic shear modulus, dynamic damping ratio, small-strain shear modulus, and small-strain damping ratio, as well as shear modulus degradation G(γ)/G, the damping ratio increase D(γ)/D, and the threshold shear strain amplitudes γ and γ. Artificially prepared fRCAs with varying fine fraction contents (0% ≤ FF ≤ 30%, within increments of 5%) have been tested at different pressures (p' = 90, 180, and 270 kPa) and relative densities of D > 65%. This study also examined the effect of two tamping-based sample preparation methods, i.e., dry and wet tamping. The results presented herein indicate that the analyzed anthropogenic material, although derived from concrete and produced by human activities, behaves very similarly to natural aggregate when subjected to dynamic loading. The introduction of a fine fraction content to fRCA leads to changes in the dynamic properties of the tested mixture. Concrete material with lower stiffness but, at the same time, with stronger damping properties can be obtained. A fine fraction content of at least 30% is sufficient to cause a significant loss of stiffness and, at the same time, a significant increase in the damping properties of the mixture. This study can serve as a reference for designing fRCA mixtures in engineering applications.
文献证实，细再生混凝土骨料（fRCA）可用于替代新拌混凝土中的天然骨料，具有诸多优势。尽管有这些优点，但fRCA在新拌混合料中的发展也存在关键障碍。其中，首要挑战是fRCA在物理、化学和力学性能方面的变异性。许多单独的研究针对不同的再生混凝土骨料（RCA）或fRCA性能展开，但很少有研究工作分析其动态性能。因此，在实验室条件下，采用标准共振柱装置以及压电元件，研究了RCA的非粘性细颗粒含量对这种废料用作特定人为土壤时动态性能的影响。在本研究中，特别关注了动态剪切模量、动态阻尼比、小应变剪切模量和小应变阻尼比，以及剪切模量衰减G(γ)/G、阻尼比增加D(γ)/D和阈值剪切应变幅值γ和γ。对不同细颗粒含量（0%≤FF≤30%，增量为5%）的人工制备fRCA在不同压力（p' = 90、180和270 kPa）和相对密度D>65%的条件下进行了测试。本研究还考察了两种基于夯实的样品制备方法，即干夯实和湿夯实的效果。本文给出的结果表明，所分析的人为材料虽然源自混凝土且由人类活动产生，但在动态加载时的行为与天然骨料非常相似。向fRCA中引入细颗粒含量会导致测试混合物动态性能的变化。可以获得刚度较低但同时阻尼性能较强的混凝土材料。至少30%的细颗粒含量足以导致刚度显著损失，同时混合物的阻尼性能显著增加。本研究可为工程应用中fRCA混合料的设计提供参考。
