Haider Imran, Yaqub Muhammad, Inam Inamullah, Ali Tariq, Qureshi Muhammad Zeeshan, Kahla Nabil Ben, Ahmed Anwar, Ahmed Hawreen
Department of Civil Engineering, University of Engineering and Technology, Taxila, Pakistan.
Department of Civil Engineering, Engineering Faculty, Laghman University, Mehtarlam, Afghanistan.
Sci Rep. 2025 Aug 12;15(1):29510. doi: 10.1038/s41598-025-11494-w.
The use of recycled aggregate (RA) as a partial or full replacement of natural aggregate (NA) is a suitable method of concrete production that has positive impacts on the environment. However, recycled aggregate concrete (RAC) has relatively lower strength and durability than that of normal concrete. To improve concrete performance, silica-fume (SF) was added with 2.5% increment up to 7.5% and metakaolin (MK) is added with a 2.5% decrement from 15 to 7.5%. The concrete with 50% RA, 10% MK and 5% SF showed notable advancement in performance after 28 days of curing. At 28 days of curing, the concrete samples had 31.5 MPa compressive strength, 5.7 MPa splitting tensile strength, and 10.6 MPa flexural strength, a strength improvement of 5.19%, 16.47%, and 8.52% over control concrete. Ultrasonic pulse velocity (UPV) indicated a 16.13% increase alongside a 20.87% reduction in water absorption which confirmed stronger bond performance and better durability of modified concrete. RCA content influences acid resistance negatively when reaching 75% RCA shows maximum deterioration. In addition, the fire resistance of such concrete resulted in higher performance at different temperature conditions for the concrete. This is due to the small particles of silica fume and metakaolin which acted as major factors and led to performance enhancements by filling in the concrete matrix gaps. The combination provides affordable, sustainable construction alternatives. Experiments show that SCMs can produce high-performance recycled concrete for modern building construction.
使用再生骨料（RA）部分或完全替代天然骨料（NA）是一种适合混凝土生产的方法，对环境有积极影响。然而，再生骨料混凝土（RAC）的强度和耐久性相对低于普通混凝土。为提高混凝土性能，添加硅灰（SF），增量为2.5%，最高至7.5%，并添加偏高岭土（MK），减量为2.5%，从15%降至7.5%。含50%RA、10%MK和5%SF的混凝土在养护28天后性能有显著提升。养护28天时，混凝土样品的抗压强度为31.5MPa，劈裂抗拉强度为5.7MPa，抗弯强度为10.6MPa，比对照混凝土的强度提高了5.19%、16.47%和8.52%。超声脉冲速度（UPV）提高了16.13%，吸水率降低了20.87%，这证实了改性混凝土的粘结性能更强，耐久性更好。当再生粗骨料（RCA）含量达到75%时，其耐酸性会产生负面影响，此时劣化程度最大。此外，这种混凝土的耐火性使其在不同温度条件下具有更高的性能。这是由于硅灰和偏高岭土的细颗粒起到了主要作用，通过填充混凝土基体间隙提高了性能。这种组合提供了经济实惠、可持续的建筑替代品。实验表明，矿物掺合料可以生产用于现代建筑施工的高性能再生混凝土。
