早期加载养护下矸石骨料混凝土强度损伤及能量耗散研究

Study on Strength Damage and Energy Dissipation of Gangue Aggregate Concrete Under Early-Age Loading and Curing

为研究早龄期加载养护对矸石骨料混凝土强度演化的影响,在第7天时对矸石骨料混凝土试样进行加载养护,第28天时开始单轴压缩试验,监测加载过程中试样的声发射振铃变化,同时采用扫描电镜观测试件的微观形貌,探究早期加载养护下矸石骨料混凝土的强度损伤及能量耗散规律。结果表明:早期承受50%~70%应力强度比的载荷可以促进试件后期强度的提高,而当早期载荷的大小超过70%的应力强度比时试件表现出强度劣化效应。早期不同应力强度比大小的载荷下养护的试样其单轴压缩过程中表现出不同的能量耗散特征,在峰值应力附近时试样内部聚集的能量突然急剧释放,探测到的声发射信号强度激增达到峰值。矸石骨料混凝土的损伤演化可视为结构模型中铰接键的断裂过程,早期一定的荷载提高了矸石骨料混凝土的自愈合能力。

In order to study the effect of early-age loading and curing on the strength evolution of gangue aggregate concrete,the gangue aggregate concrete specimens were loaded and cured on the 7th day,and the uniaxial compression test was started on the 28th day to monitor the acoustic emission ringing changes of the specimens during loading.At the same time,the microstructure of the specimens was observed by scanning electron microscopy to explore the strength damage and energy dissipation of gangue aggregate concrete under early loading and curing.The results show that the bearing the load with 50%-70%of stress intensity ratio in early age can promote the later strength of the specimen,while the specimen shows deterioration effect when the stress intensity ratio exceeds 70%.The specimens cured under the load with different stress intensity ratios in the early age showed different energy dissipation characteristics during uniaxial compression.The energy accumulated inside the specimen suddenly released sharply near the peak stress,and the detected acoustic emission signal intensity surged to the peak.The damage evolution of gangue aggregate concrete can be regarded as the fracture process of hinged key in the structural model.A certain load in the early age can improve the self-healing ability of gangue aggregate concrete.