Strength performance and microscopic mechanism of cement mortar incorporating fine recycled concrete aggregate and natural sand

作者：Erlu Wu, Xukun Ma, Chulei Fang, Na Li, Liang Jia, Ping Jiang, Wei Wang · 发表于：Journal of Building Engineering · 年份：2025 · DOI：10.1016/j.jobe.2025.111767 · 被引用次数：13 · 研究领域：Recycled Aggregate Concrete Performance、Innovations in Concrete and Construction Materials、Innovative concrete reinforcement materials

The resource utilization of waste concrete offers significant environmental and economic benefits by mitigating the environmental issues associated with its disposal and reducing the consumption of natural resources . However, waste concrete aggregates with a particle size greater than 4.75 mm will reduce the mechanical strength of recycled aggregate concrete (RAC). In this study, waste concrete was crushed into aggregates with a particle size of less than 4.75 mm to replace natural sand at varying substitution rates (0 %, 20 %, 30 %, 40 %, 50 %, 60 %, 80 % and 100 %). The impact of these substitution rates on the strength characteristics of recycled aggregate mortar (RAM) was thoroughly examined. The experimental results indicate that the substitution rate of recycled concrete aggregate (RCA) significantly influences the compressive and flexural strengths of RAM, with the optimum strength observed at a substitution rate of 40 %. At 28 days, the compressive strength reached 5.8 MPa and the flexural strength was 2.6 MPa, representing a 10 % and 21 % increase, respectively, compared to the control group. Additionally, the compressive strength of all RAM mixtures with varying RCA substitution rates met the strength requirement for M5 mortar at 28 days. Microscopic analyses revealed that the incorporation of RCA led to changes in the mineral composition, particularly an increase in SiO 2 , CaCO 3 and Ca(OH) 2 content. Furthermore, the presence of RCA enhanced the hydration of cem...