1.Hohai University;2.Yangzhou University
To study the influence of freeze-thaw on the evolution of steam-cured concrete mechanical properties. In response to this problem, the freeze-thaw cycle test and uniaxial compression-acoustic emission test of steam-cured concrete specimens were carried out to analyze the damage characteristics of concrete under different steam-curing systems under the action of freeze-thaw cycles. According to the characteristic parameters of acoustic emission, a constitutive model of steam-cured concrete damage was established under freeze-thaw conditions, and the relationship between damage variables and the number of freeze-thaw cycles was discussed. The results show that the 60℃ and 80℃ steam curing temperature is not good for the frost resistance of concrete, and there is no significant difference between 40℃ steam-cured concrete and standard-cured concrete in frost resistance. The change of the acoustic emission ringing count in the process of concrete compression failure shows obvious three-stage changes in contact period, quiet period and spike period. The demarcation point between the quiet period and the spike period shifts back in time with the increase in the number of freeze-thaw cycles. In the early stage of the compression process, the damage of steam-cured concrete develops slowly; when the relative peak stress reaches 0.8, the damage of steam-cured concrete develops more rapidly until it fails under compression.