等强度条件下的HVFAC关键抗裂物性的时变性及其评价

It is an important task in theory and practice to study the time dependence of key crack resistance properties of High volume fly ash concrete (HVFAC) and their evaluation. Considering the limitations in previous study and urgent demands in engineering, HVFAC is used as object of this proposal study. In order to investigate the time dependence of key crack resistance properties, strength class, dosage of fly ash, curing condition, drying initial age, restraining degree, loading age and stress-strength ratio are considered as experimental parameters. By designing the experiment systematically, the volume change Including thermal deformation, autogenous shrinkage and drying shrinkage, and time dependence of key crack resistance properties, such as tensile strength, tensile modulus, thermal expansion coefficient, ultimate tensile strain and tensile creep of HVFAC under same strength, are obtained. Based on the original method, the development of stress due to restraining volume change under different parameters is discussed, and stress components are separated to analysis their contribution to total stress. By using meso-analysis method, the mechanism of generation and development of volume change and creep are investigated. Further, the precise evaluation models on the volume change and time dependence of key crack resistance properties are built. The results of the study will be help to design crack resistance materials, and provide basic parameters for highly precise stress analysis, and references for related technical code, specification and standard.

大掺量粉煤灰混凝土（HVFAC）关键抗裂物性的时变性及其评价是理论和实践意义重大的课题。针对既有研究存在的问题和工程实际的需要，本项目以HVFAC为研究对象，以强度等级、粉煤灰掺量、养护条件、干燥开始龄期、约束程度、加载龄期以及应力水平等为主要参数。通过系统的实验设计，把握等强度条件下HVFAC的温度变形、自收缩、干燥收缩及其复合作用下的体积变化变形以及抗拉强度、拉伸弹性模量、热膨胀系数、极限拉伸应变、拉伸徐变等关键抗裂物性及其时变特征；基于独创的约束实验方法，考察不同参数下约束应力的发展规律，分离并表征各应力成分的影响度；运用细观分析手段，研究HVFAC体积变化和徐变的发生发展机制。进而，建立体积变化变形与关键抗裂物性及其时变性的评价和预测方法。本项目可为抗裂性HVFAC的材料设计提供理论指导，为应力的计算分析提供准确的基本参数，为相关设计、施工规范、标准编制提供参考依据。

大掺量粉煤灰混凝土（HVFAC）关键抗裂物性的时变性及其评价是理论和实践意义重大的课题。针对既有研究存在的问题和工程实际的需要，本项目以HVFAC为研究对象，以强度等级、粉煤灰掺量、养护条件、干燥开始龄期、约束程度、加载龄期以及应力水平等为主要参数。通过系统的实验设计，把握等强度条件下HVFAC的温度变形、自收缩、干燥收缩及其复合作用下的体积变化变形以及抗拉强度、拉伸弹性模量、热膨胀系数、极限拉伸应变、拉伸徐变等关键抗裂物性及其时变特征；基于独创的约束实验方法，考察了不同参数下约束应力的发展规律，分离并表征了各应力成分的影响，分析了HVFAC体积变化和徐变的发生发展机制。进而，建立了体积变化变形与关键抗裂物性及其时变性的评价和预测方法；基于人工神经网络，提出了等强度HVFAC配合比关键参数的设计方法和抗裂性的评价方法。本项目可为抗裂性HVFAC的材料设计提供理论指导，为应力的计算分析提供准确的基本参数，为相关设计、施工规范、标准编制提供参考依据。