考虑龄期影响的再生混凝土力学性能及损伤机制研究  

STUDY ON MECHANICAL PROPERTIES AND DAMAGE MECHANISM OF RECYCLED CONCRETE CONSIDERING THE EFFECT OF AGE

作　　者：白卫峰 耿越 管俊峰 苑晨阳 谢超鹏 陆孝峰 BAI Wei-feng;GENG Yue;GUAN Jun-feng;YUAN Chen-yang;XIE Chao-peng;LU Xiao-feng(School of Water Conservancy,North China University of Water Resources and Electric Power,Zhengzhou 450046,China;School of Civil Engineering and Communication,North China University of Water Resources and Electric Power,Zhengzhou 450045,China)

机构地区：[1]华北水利水电大学水利学院,郑州450046 [2]华北水利水电大学土木与交通学院,郑州450045

出　　处：《工程力学》2025年第2期127-141,共15页Engineering Mechanics

基　　金：国家自然科学基金项目(51679092,52179132);河南省高等学校青年骨干教师培养计划项目(2021GGJS074)。

摘　　要：研究了不同养护龄期下含偏高岭土(MK)再生骨料混凝土(RAC)的单轴压缩力学性能和损伤演化规律。制备了MK含量分别为0%和15%的RAC试件,获取了不同龄期下RAC试件的应力-应变全曲线。利用核磁共振(NMR)分析RAC内部孔隙率以及孔径分布的变化情况;利用扫描电子显微镜(SEM)分析水化产物的微观形貌特征,探讨MK的掺入对孔结构改善的微观机理;通过声发射(AE)监测RAC微裂纹发展过程。研究结果表明:随着龄期的增长,试件内部水化反应进一步充分,峰值应力和弹性模量逐渐增大,峰值应变呈减小趋势,应力-应变曲线的上升段和下降段的连接部分由平缓变得陡峭;加入MK改善了试件的微观结构,提高了峰值应力、弹性模量和峰值应变。结合统计损伤理论,考虑存在断裂和屈服两种细观损伤模式,通过对5个特征参数E_(0)、ε_(a)、ε_(h)、ε_(b)和H演化规律的分析,揭示龄期和MK对RAC细观损伤机制的影响规律;从有效应力的角度解释了AE峰值信号滞后于峰值应力的现象。提出“有效应力极值”理论,进一步讨论了复杂条件下混凝土细观损伤演化机制之间的内在联系。Studied were the uniaxial compressive mechanical properties and damage evolution of recycled aggregate concrete(RAC)containing metakaolin(MK)at different curing ages.Prepared were RAC specimens with MK content of 0%and 15%,and obtained were the stress-strain full curves of RAC specimens at different ages.Nuclear magnetic resonance(NMR)was used to analyze the variation of porosity as well as the pore size distribution inside the RAC;scanning electron microscopy(SEM)was used to analyze the microscopic morphological characteristics of the hydration products in order to explore the microscopic mechanism of MK incorporation on the improvement of the pore structure;and acoustic emission(AE)was used to monitor the development process of microcracks in the RAC.The results showed that:with the growth of age,the hydration reaction was further sufficient,the peak stress and elastic modulus were gradually increased,the peak strain tended to decrease,the connection between the ascending section and the descending part of the stress-strain curve changed from flat to steep;and the addition of MK improved the microstructure of the specimen,of the peak stress and,of the elastic modulus and peak strain.Combined with the statistical damage theory,considering the existence of fracture and yield mesoscopic damage modes,revealed were the effects of age and MK on the mesoscopic damage mechanism of RAC by analyzing the evolution law for five characteristic parameters E_(0),ε_(a),ε_(h),ε_(b) and H;explained from the perspective of effective stress was the phenomenon that the peak signal of AE lagged behind the peak stress.The theory of"effective stress extremum"was put forward,and the internal relationship between the mesoscopic damage evolution mechanism of concrete under complex conditions was further discussed.

关 键 词：再生骨料混凝土 单轴压缩 细观损伤机制 偏高岭土 养护龄期 

分 类 号：TU528.01[建筑科学—建筑技术科学]