Zhang Hua, Pan Qi, Zheng Kai, Jin Chuanjun, Pan Luoyu
College of Civil and Transportation Engineering, Hohai University, Nanjing 210009, China.
Materials (Basel). 2022 Jun 22;15(13):4416. doi: 10.3390/ma15134416.
In this paper, the mesoscale damage properties of concrete and mortar were studied experimentally under Brazilian disc splitting tensile tests combining X-ray computed tomography (CT) and digital image correlation (DIC) technology. Considering the factors of water/cement ratios and loading rates, the influence of meso components on the macro tensile properties and failure modes of concrete were studied. The experimental results and analysis indicate that the following: (1) the existence of coarse aggregate makes the tensile strength of concrete lower than that of mortar and reduces the sensitivity of tensile strength to the loading rates; (2) the failure modes of mortar and concrete Brazilian discs differ in the crack initiation positions and localization phenomena. Under high loading rates, the local failure plays a critical role in the strength improvement of concrete; (3) for concrete, interface failure and mortar failure are the main failure modes under low loading rates, whereas aggregate failure gradually becomes the main failure mode with increasing loading rates. The decrease in water/cement ratios improves the strength of the mortar matrix and interfacial bonding performance, leading to more serious aggregate damage and higher strength.
本文结合X射线计算机断层扫描（CT）和数字图像相关（DIC）技术，在巴西圆盘劈裂拉伸试验下对混凝土和砂浆的细观损伤特性进行了试验研究。考虑水灰比和加载速率等因素，研究了细观组分对混凝土宏观拉伸性能和破坏模式的影响。试验结果及分析表明：（1）粗骨料的存在使混凝土的抗拉强度低于砂浆，并降低了抗拉强度对加载速率的敏感性；（2）砂浆和混凝土巴西圆盘的破坏模式在裂纹起裂位置和局部化现象方面存在差异。在高加载速率下，局部破坏对混凝土强度提高起关键作用；（3）对于混凝土，在低加载速率下界面破坏和砂浆破坏是主要破坏模式，而随着加载速率增加骨料破坏逐渐成为主要破坏模式。水灰比的降低提高了砂浆基体强度和界面粘结性能，导致骨料损伤更严重且强度更高。
