Fattouh Mohy S, Abouelnour Mohamed A, Mahmoud Alaa A, Fathy Islam N, El Sayed A F, Elhameed Sameh A, Nabil Islam M
Civil Engineering Department, Faculty of Engineering, Sinai University, Arish, Egypt.
Civil Engineering Department, Faculty of Engineering, Fayoum University, Fayoum, Egypt.
Sci Rep. 2025 May 26;15(1):18428. doi: 10.1038/s41598-025-02655-y.
The increasing need for sustainable construction practices has driven research into the utilization of recycled concrete aggregate (RCA) in new concrete mixes. However, the variable properties of RCA, particularly its gradation, can significantly impact the performance of the resulting concrete. This study investigates the impact of modified aggregate gradation on the properties of concrete incorporating 100% RCA. Three concrete mixes were prepared: a control mix with the original RCA gradation (RCA1) and two modified mixes (RCA2 and RCA3). The initial gradation was modified by enhancing the 10% passing the #1″ sieve (S1) and diminishing the combined 10% passing the #1″ sieve and 10% passing the #4″ sieve (S2). Subsequently, the effects of these modified gradations were assessed, encompassing workability, mechanical properties (compressive and flexural strength), microstructural characteristics (XRD, SEM, and EDX), and radiation shielding performance. Results demonstrate that, despite reduced workability, the modified mixes exhibited enhanced compressive and flexural strengths. Microstructural analysis revealed denser, more interconnected cement paste matrices and refined interfacial transition zones (ITZ) in the modified mixes. Furthermore, the radiation shielding effectiveness increased with increasing gradation modification (RCA1 < RCA2 < RCA3). Specifically, RCA3 exhibited the lowest half-value layer (HV), tenth-value layer (TV), and mean free path (MF), along with the highest average macroscopic removal cross-section (FCS). These results suggest that modifying the gradation of RCA can effectively improve the mechanical and radiation shielding properties of concrete made with 100% RCA. This enhanced performance makes RCA concrete a viable option for radiation shielding applications in facilities like hospitals and nuclear power plants, contributing to both sustainable construction and improved safety.
对可持续建筑实践的需求不断增加，推动了对再生混凝土骨料（RCA）在新型混凝土混合料中应用的研究。然而，RCA的可变特性，尤其是其级配，会对所得混凝土的性能产生重大影响。本研究调查了改性骨料级配对掺入100%RCA的混凝土性能的影响。制备了三种混凝土混合料：一种是具有原始RCA级配的对照混合料（RCA1）和两种改性混合料（RCA2和RCA3）。通过增加过1英寸筛（S1）的10%并减少过1英寸筛的10%和过4英寸筛（S2）的10%的总和来修改初始级配。随后，评估了这些改性级配的效果，包括工作性、力学性能（抗压强度和抗弯强度）、微观结构特征（XRD、SEM和EDX）以及辐射屏蔽性能。结果表明，尽管工作性降低，但改性混合料的抗压强度和抗弯强度有所提高。微观结构分析显示，改性混合料中水泥浆体基质更致密、相互连接更紧密，界面过渡区（ITZ）更细化。此外，辐射屏蔽效果随着级配改性程度的增加而提高（RCA1＜RCA2＜RCA3）。具体而言，RCA3表现出最低的半值层（HV）、十分之一值层（TV）和平均自由程（MF），以及最高的平均宏观去除截面（FCS）。这些结果表明，修改RCA的级配可以有效改善由100%RCA制成的混凝土的力学性能和辐射屏蔽性能。这种增强的性能使RCA混凝土成为医院和核电站等设施辐射屏蔽应用的可行选择，有助于可持续建筑和提高安全性。
