This study investigates the behaviour of concrete manufactured with recycled coarse aggregate (RCA) derived from multiple recycling cycles, with a particular emphasis on experimental and numerical assessment of shrinkage at different curing temperatures (20, 40, and 60 °C). Four types of concretes have been produced: a natural aggregate concrete (NAC) with 100 % natural coarse aggregate (NCA) and three generations of recycled aggregate concrete (RAC) where NCA is replaced by RCA with volume percentages of 50 % and 100 % in each generation. Moreover, silica fume is used to improve the mechanical performance of the third-generation recycled concrete with 100 % RCA. In addition, the total shrinkage was predicted by combining the maturity method with finite-element analysis (FEA), using ANSYS© software. The results revealed that the multi-recycling and the replacement ratio of RCA have a detrimental impact on the mechanical properties. The total shrinkage increases considerably with both increasing curing temperature and increasing RCA replacement ratios in each generation. Furthermore, silica fume has a beneficial effect on the mechanical performance of the multi-recycled concrete; nevertheless, it causes an increase in the total shrinkage. Finally, the comparison between the experimental and numerical data shows that the FEA model, using the maturity method and two-phase serial model, can yield an accurate prediction of the total shrinkage of multi-recycled concrete.

中文翻译：

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多种再生粗骨料混凝土的力学性能，特别强调不同养护温度下收缩的实验和数值评估

本研究研究了使用来自多个回收循环的再生粗骨料 (RCA) 制造的混凝土的行为，特别强调不同固化温度（20、40 和 60 °C）下收缩的实验和数值评估。已生产四种类型的混凝土：100％天然粗骨料（NCA）的天然骨料混凝土（NAC）和三代再生骨料混凝土（RAC），其中NCA被RCA取代，体积百分比为50％和100％每一代。此外，硅灰还用于提高100% RCA第三代再生混凝土的机械性能。此外，使用 ANSYS© 软件将成熟度方法与有限元分析 (FEA) 相结合来预测总收缩量。结果表明，RCA的多次回收和替代率对力学性能产生不利影响。随着每一代固化温度的增加和 RCA 替换率的增加，总收缩率显着增加。此外，硅粉对多元再生混凝土的力学性能也有有益的影响；然而，它会导致总收缩率增加。最后，实验数据与数值数据的比较表明，利用成熟度法和两相序列模型的有限元分析模型可以准确预测多重再生混凝土的总收缩。