Zhou Jie, Hao Shengpeng, Chen Yong, Zhang Shurong, Xu Wenyu
Lanzhou Coal Mine Design and Research Institute Co., Ltd, Lanzhou, 730000, China.
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China.
Sci Rep. 2025 Aug 6;15(1):28663. doi: 10.1038/s41598-025-14014-y.
The large‑scale accumulation of coal gangue poses serious environmental and land‑use challenges, yet its direct use as concrete aggregate has been hindered by low reactivity, high porosity, and weak interfacial bonding. Although prior studies have examined thermal activation of coal gangue, the interplay among calcination temperature, pore‑size evolution, and mesoscale failure mechanisms in a unified multi‑scale framework remains underexplored. This study presents a multi‑scale experimental and numerical investigation of thermally activated coal gangue aggregate concrete, focusing on ITZ evolution and failure mechanisms. Coal gangue was calcined at 500, 600, 700, and 800 °C and substituted for natural coarse aggregate in C30 concrete. Uniaxial compression testing, SEM, XRD, NMR, and PFC3D meso‑scale simulations were employed to elucidate the effects of calcination temperature on 28‑day compressive strength, ITZ microstructure, pore‑size distribution, and crack initiation and propagation. Calcination at 700-800 °C maximized the release of active SiO₂/Al₂O₃, resulting in a denser ITZ, reduced porosity, and a 15.6-22.8% increase in compressive strength over uncalcined concrete. Calibrated meso‑scale models demonstrated that enhanced ITZ bond strength delayed crack onset and altered damage patterns. These findings offer theoretical insight and practical guidance for the sustainable valorization of coal gangue in high‑performance concrete applications.
煤矸石的大规模堆积带来了严峻的环境和土地利用挑战，然而其作为混凝土骨料的直接应用却因反应活性低、孔隙率高和界面粘结弱而受到阻碍。尽管先前的研究已经考察了煤矸石的热活化，但在统一的多尺度框架下，煅烧温度、孔径演化和细观破坏机制之间的相互作用仍未得到充分探索。本研究对热活化煤矸石骨料混凝土进行了多尺度实验和数值研究，重点关注界面过渡区（ITZ）的演化和破坏机制。将煤矸石在500、600、700和800℃下煅烧，并用其替代C30混凝土中的天然粗骨料。采用单轴压缩试验、扫描电子显微镜（SEM）、X射线衍射（XRD）、核磁共振（NMR）和颗粒流代码3D（PFC3D）细观尺度模拟，以阐明煅烧温度对28天抗压强度、ITZ微观结构、孔径分布以及裂纹萌生和扩展的影响。在700 - 800℃下煅烧可使活性SiO₂/Al₂O₃的释放最大化，从而形成更致密的ITZ，降低孔隙率，抗压强度比未煅烧的混凝土提高15.6 - 22.8%。经过校准的细观尺度模型表明，增强的ITZ粘结强度延迟了裂纹的起始并改变了损伤模式。这些发现为煤矸石在高性能混凝土应用中的可持续增值提供了理论见解和实际指导。
