混凝土结构早龄期开裂问题近年来日益得到重视和关注，其影响水利工程的耐久性和安全性。高吸水性树脂内养护技术是解决开裂问题的措施之一。混凝土早龄期拉伸徐变模型是评价抗裂性能的重要依据，但目前还缺乏高吸水性树脂内养护混凝土早龄期拉伸徐变预测模型。本项目基于申请人近10年来在混凝土早龄期裂缝诊治方面的研究工作及国家和省基金的资助项目开展工作。通过温度应力试验机试验、声发射试验、微细观试验和理论分析相结合的方法，重点解决高吸水性树脂内养护混凝土早龄期线性和非线性拉伸徐变分界点确定、轴向约束条件下早龄期拉伸徐变特性分析和早龄期拉伸徐变预测模型构建三个关键科学问题。在揭示拉伸徐变机理的基础上，提出考虑引水量、加载龄期、养护温度、应力强度比和轴向约束条件等影响因素的高吸水性树脂内养护混凝土早龄期拉伸徐变预测模型。本项目的目的是为高吸水性树脂内养护混凝土结构的早龄期抗裂性能和开裂风险评估方法提供进一步补充。

The early age cracking resistance of concrete structures is of special interest in recent years. The early age cracking affects the durability and safety of water conservancy project.The internal curing technology with super absorbent polymer (SAP) is one of the measures to improve the cracking resistance of concrete. The prediction models for tensile creep of early age concrete are necessary to evalute the cracking resistance, however, few models are available for evaluating the early age tensile creep of concrete internally cured with SAP. The research work of this project is based on the study result of inspection and retrofitting of early age cracking of concrete from the applicant and the financial support of the National Natural Science Foundation of China (NSFC) and Natural Science Foundation of Jiangsu Province. The Temperature Stress Test Machine test (TSTM), the acoustic emission test and the microsacle and mesoscale test as well as theoretical analysis are used in this project. The following three key problems will be solved: (1) the limit between linear and nonlinear tensile creep of concrete internally cured with SAP at early age; (2) the early age tensile creep behavior of concrete internally cured with SAP under axial restraint condition; and (3) the prediction models for early age tensile creep. The influence factors such as internal curing water, loading age, curing temperature, and stress to strength as well as axial restraint condition will be included in the prediction models. The mechanisms of early age tensile creep of concrete internally cured with SAP will also be investigated. The result of this project can be used for evaluating the early age cracking resistance and cracking potential of concrete internally cured with SAP.