Trottier Cassandra, de Grazia Mayra T, Macedo Hian F, Sanchez Leandro F M, Andrade Gabriella P de, de Souza Diego J, Naboka Olga, Fathifazl Gholamreza, Nkinamubanzi Pierre-Claver, Demers André
Department of Civil Engineering, Faculty of Engineering, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
National Research Council Canada (NRCC), Ottawa, ON K1A 0R6, Canada.
Materials (Basel). 2022 Feb 11;15(4):1342. doi: 10.3390/ma15041342.
The pressure to use sustainable materials and adopt practices reducing the carbon footprint of the construction industry has risen. Such materials include recycled concrete aggregates (RCA) made from waste concrete. However, concrete made with RCA often presents poor fresh and hardened properties along with a decrease in its durability performance, especially when using its fine fraction (i.e., FRCA). Most studies involving FRCA use direct replacement methods (DRM) to proportion concrete although other techniques are available such as the Equivalent Volume (EV) and Particle Packing Models (PPMs); yet their impact on the durability performance, especially its performance against freezing and thawing (F/T), remains unknown. This work, therefore, appraises the F/T resistance of FRCA mixtures proportioned through various mix proportioning techniques (i.e., DRM, EV and PPMs), produced with distinct crushing processes (i.e., crusher's fines vs. finely ground). The results show that the mix design technique has a significant influence on the FRCA mixture's F/T resistance where PPM-proportioned mixtures demonstrate the best overall performance, exceeding the specified requirements while DRM-proportioned mixtures failed F/T resistance requirements. Moreover, the crushing process plays an important role in the recycled mixtures' cracking behavior under F/T cycles, where less processing leads to fewer cracks while remaining the most sustainable option overall.
使用可持续材料并采用减少建筑业碳足迹的做法的压力日益增大。此类材料包括由废弃混凝土制成的再生混凝土骨料（RCA）。然而，用RCA制成的混凝土通常呈现出较差的新拌性能和硬化性能，同时其耐久性也会下降，尤其是在使用其细颗粒（即FRCA）时。大多数涉及FRCA的研究采用直接替代法（DRM）来配合比混凝土，尽管还有其他技术，如等效体积法（EV）和颗粒堆积模型（PPM）；然而，它们对耐久性的影响，尤其是其抗冻融（F/T）性能，仍然未知。因此，这项工作评估了通过各种配合比技术（即DRM、EV和PPM）配合比的FRCA混合物的抗冻融性能，这些混合物采用了不同的破碎工艺（即破碎机细粉与细磨）。结果表明，配合比设计技术对FRCA混合物的抗冻融性能有显著影响，其中PPM配合比的混合物总体性能最佳，超过了规定要求，而DRM配合比的混合物未达到抗冻融性能要求。此外，破碎工艺在冻融循环下再生混合物的开裂行为中起着重要作用，较少的加工导致较少的裂缝，同时总体上仍是最可持续的选择。
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