Huang Yijie, Zheng Lina, Li Peng, Wang Qing, Zhang Yukun
College of Civil Engineering and Architecture, Shandong University of Science and Technology, Qingdao 266590, China.
College of Mechanical and Architectural Engineering, Taishan University, Tai'an 271000, China.
Materials (Basel). 2024 Aug 19;17(16):4100. doi: 10.3390/ma17164100.
The fracture mechanism and macro-properties of SVSAC were studied using a novel test system combined with numerical simulations, which included three-point bending beam tests, the digital image correlation (DIC) technique, scanning electron microscopy (SEM), and ABAQUS analyses. In total, 9 groups and 36 specimens were fabricated by considering two critical parameters: initial notch-to-depth ratios (/) and concrete mix components (seawater and volcanic scoria coarse aggregate (VSCA)). Changes in fracture parameters, such as the load-crack mouth opening displacement curve (-CMOD), load-crack tip opening displacement curve (-CTOD), and fracture energy (), were obtained. The typical double- fracture parameters (i.e., initial fracture toughness (KICini) and unstable fracture toughness (KICun)) and tension-softening (-CTOD) curve were analyzed. The test results showed that the initial cracking load (), , and characteristic length () of the SVSAC increased with decreasing /. Compared with the ordinary concrete (OC) specimen, the -CMOD and -CTOD curves of the specimen changed after using seawater and VSCA. The evolution of the crack propagation length was obtained through the DIC technique, indicating cracks appeared earlier and the fracture properties of specimen decreased after using VSCA. Generally, the KICun and KICini of SVSAC were 36.17% and 8.55% lower than those of the OC specimen, respectively, whereas the effects of / were negligible. The reductions in , , and of the specimen using VSCA were 10.94%, 32.66%, and 60.39%, respectively; however, seawater efficiently decreased the negative effect of VSCA on the fracture before the cracking width approached 0.1 mm. Furthermore, the effects of specimen characteristics on the fracture mechanism were also studied through numerical simulations, indicating the size of the beam changed the fracture toughness. Finally, theoretical models of the double- fracture toughness and the -CTOD relations were proposed, which could prompt their application in marine structures.
采用一种结合数值模拟的新型测试系统，对海水火山渣混凝土（SVSAC）的断裂机理和宏观性能进行了研究，该系统包括三点弯曲梁试验、数字图像相关（DIC）技术、扫描电子显微镜（SEM）和ABAQUS分析。总共制作了9组36个试件，考虑了两个关键参数：初始缺口深度比（/）和混凝土混合料成分（海水和火山渣粗骨料（VSCA））。获得了断裂参数的变化，如荷载-裂缝口张开位移曲线（-CMOD）、荷载-裂缝尖端张开位移曲线（-CTOD）和断裂能（）。分析了典型的双断裂参数（即初始断裂韧性（KICini）和失稳断裂韧性（KICun））以及拉伸软化（-CTOD）曲线。试验结果表明，SVSAC的初始开裂荷载（）、和特征长度（）随/的减小而增加。与普通混凝土（OC）试件相比，使用海水和VSCA后试件的-CMOD和-CTOD曲线发生了变化。通过DIC技术获得了裂缝扩展长度的演变，表明使用VSCA后裂缝出现更早，试件的断裂性能降低。一般来说，SVSAC的KICun和KICini分别比OC试件低36.17%和8.55%，而/的影响可忽略不计。使用VSCA的试件的、和分别降低了10.94%、32.66%和60.39%；然而，在裂缝宽度接近0.1mm之前，海水有效地降低了VSCA对断裂的负面影响。此外，还通过数值模拟研究了试件特性对断裂机理的影响，表明梁的尺寸改变了断裂韧性。最后，提出了双断裂韧性和-CTOD关系的理论模型，这可以促进它们在海洋结构中的应用。
