关键词: 高掺量粉煤灰大坝混凝土, 温度-应力试验, 早龄期, 拉伸徐变, 水化发展进程, 开尔文模型

Abstract: To determine the tensile creep of dam concrete at early age, this study conducts an experiment on the development of temperature, deformation, and restraint stress of fly ash dam concrete, using temperature-stress test technology and considering comprehensively its hydration process and restraint state at early age. We test restrained specimens and free specimens of concrete materials with fly ash contents of 35% and 80% under different temperature curing conditions, and obtain their early age tensile creep and developing trends. By the measurements of temperature-stress tests and adiabatic temperature rise tests, we develop and verify a tensile creep model of the concrete materials at early age under variable temperature history based on an improved Kelvin model. The results show the concrete with 80% fly ash has a larger specific tensile creep and slower development of restraint stress, a condition favorable to its crack resistance. The improved Kelvin model, based on a better consideration of the hydration process, can predict the tensile creep of dam concrete at early age under the restraint condition, and is useful to the assessment of early age cracking risk.

Key words: high content fly ash dam concrete, temperature-stress test, early age, tensile creep, hydration process, Kelvin model