Zhang Shukun, Wu Xinghui, Jiang Peng, Wang Haohao, Wang Shuai, Yang Haojie, Lu Lu
School of City and Architecture Engineering, Zaozhuang University, Zaozhuang, 277160, Shandong, China.
School of Civil Engineering, Liaoning Technical University, Fuxin, 123000, Liaoning, China.
Sci Rep. 2025 Jan 14;15(1):1961. doi: 10.1038/s41598-024-84903-1.
To study the enhancement effect of carbon nanotubes (CNTs) on the splitting tensile properties of foamed concrete backfill in which cement and fly ash were used as the cementitious materials and natural sand was used as the aggregate, specimens of CNT-modified foamed concrete backfill were prepared. Brazilian splitting tests were used to investigate the splitting tensile strength of the CNT-modified foamed concrete backfill, and the digital speckle correlation method was used to analyze the stress field characteristics and crack expansion law of the specimens during splitting tensile testing. The stress-strain characteristics and energy dissipation laws of the backfill were studied at various static loading rates, and a relationship between the splitting tensile strength, ultimate strain, and loading rate was established. The results showed that at the optimum CNT content of 0.05%, the peak strength and ultimate strain of the modified foamed concrete backfill increased by an average of 67.2% and 21.7%, respectively. Moreover, after modification with CNTs, the foamed concrete backfill was less likely to develop strain concentration areas before reaching peak strength. The triangular stable loadbearing structure formed by the modified foamed concrete backfill after splitting caused the end of the stress-strain curve to exhibit varying degrees of "backlash". For the CNT-modified foamed concrete backfill, the peak strength correlated logarithmically with the loading rate, while the ultimate strain correlated as a power function of the loading rate. At a low loading rate, the CNT-modified foamed concrete backfill dissipated less energy, and the reverse was true for higher rates.
为研究以水泥和粉煤灰为胶凝材料、天然砂为骨料的泡沫混凝土回填材料中碳纳米管（CNTs）对其劈裂拉伸性能的增强效果，制备了碳纳米管改性泡沫混凝土回填材料试件。采用巴西劈裂试验研究碳纳米管改性泡沫混凝土回填材料的劈裂抗拉强度，采用数字散斑相关方法分析试件在劈裂拉伸试验过程中的应力场特征和裂纹扩展规律。研究了回填材料在不同静态加载速率下的应力-应变特性和能量耗散规律，并建立了劈裂抗拉强度、极限应变与加载速率之间的关系。结果表明，在碳纳米管最佳含量为0.05%时，改性泡沫混凝土回填材料的峰值强度和极限应变分别平均提高了67.2%和21.7%。此外，经碳纳米管改性后，泡沫混凝土回填材料在达到峰值强度之前不易出现应变集中区域。改性泡沫混凝土回填材料劈裂后形成的三角形稳定承载结构使应力-应变曲线末端呈现出不同程度的“回冲”现象。对于碳纳米管改性泡沫混凝土回填材料，峰值强度与加载速率呈对数关系，而极限应变与加载速率呈幂函数关系。在低加载速率下，碳纳米管改性泡沫混凝土回填材料耗能较少，而在高加载速率下则相反。
