混凝土硬化过程中的应力-应变发展和基于内部湿度的开裂风险预估

STRESS-STRAIN DEVELOPMENT AND PREDICTION OF CRACKING POTENTIAL BASED ON HUMIDITY DROP RATE OF HARDENING CONCRETE

  • 摘要: 建立了一种对水泥混凝土开裂风险进行评估的新方法。模型基于硬化过程中混凝土的应变-约束应力发展, 研究了开裂时间与收缩变形率和混凝土内部湿度降低率的关系。研究结果表明:混凝土开裂风险与收缩变形速率有关, 开裂时间与开裂时的临界收缩率存在唯一对应关系。该研究根据混凝土湿度与变形的关系, 提出了一个基于混凝土内部湿度降低速率的混凝土早期开裂预估方法。该方法避免了工程实际中为确定混凝土开裂风险而需要进行的变形测量及复杂的需要考虑徐变、应力松弛、强度和模量的发展等因素但又未必准确的应力计算过程, 简化了混凝土硬化过程中的开裂风险预测。

     

    Abstract: In this study, the early-age tensile stress development and cracking potential were investigated on cement paste and concrete. It was found that the cracking potential is closely related to the shrinkage rate rather than the shrinkage magnitude. A unique relationship was found exist between the shrinkage rate and cracking time for cement paste. The cracking time was then expressed as a function of a relative humidity (RH) drop rate and the aggregate content of mixtures. This study proposes a new methodology for evaluating cracking potential and has implications for mitigating early-age cracking in concrete members.

     

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