Tan Xin, Hu Zhengbo, Li Wengui, Zhou Suhua, Li Tenglong
College of Civil Engineering, Hunan University, Changsha 410082, China.
Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education, Hunan University, Changsha 410082, China.
Materials (Basel). 2020 Sep 29;13(19):4329. doi: 10.3390/ma13194329.
This paper investigates the failure processes of recycled aggregate concrete by a model test and numerical simulations. A micromechanical numerical modeling approach to simulate the progressive cracking behavior of the modeled recycled aggregate concrete, considering its actual meso-structures, is established based on the discrete element method (DEM). The determination procedure of contact microparameters is analyzed, and a series of microscopic contact parameters for different components of modeled recycled aggregate concrete (MRAC) is calibrated using nanoindentation test results. The complete stress-strain curves, cracking process, and failure pattern of the numerical model are verified by the experimental results, proving their accuracy and validation. The initiation, growth, interaction, coalescence of microcracks, and subsequent macroscopic failure of the MRAC specimen are captured through DEM numerical simulations and compared with digital image correlation (DIC) results. The typical cracking modes controlled by meso-structures of MRAC are concluded according to numerical observations. A parameter study indicates the dominant influence of the macroscopic mechanical behaviors from the shear strength of the interfacial transition zones (ITZs).
本文通过模型试验和数值模拟研究再生骨料混凝土的破坏过程。基于离散元法（DEM），建立了一种考虑再生骨料混凝土实际细观结构的细观力学数值模拟方法，以模拟其渐进开裂行为。分析了接触微观参数的确定过程，并利用纳米压痕试验结果校准了再生骨料混凝土模型（MRAC）不同组分的一系列微观接触参数。通过试验结果验证了数值模型的完整应力-应变曲线、开裂过程和破坏模式，证明了其准确性和有效性。通过DEM数值模拟捕捉了MRAC试件微裂纹的萌生、扩展、相互作用、贯通以及随后的宏观破坏，并与数字图像相关（DIC）结果进行了比较。根据数值观测结果，总结了由MRAC细观结构控制的典型开裂模式。参数研究表明，界面过渡区（ITZs）的抗剪强度对宏观力学行为具有主导影响。
